Ncert solutions for class 10 science chapters:.
What is meant by power of a lens, what is absolute refractive index, when a convex lens will act as magnifying glass, which mirror give an erect and enlarged image of an object, contact form.
Important Questions for Class 10 Science Chapter 10 Light Reflection and Refraction covers each topic of the chapter. These questions aim at providing a better understanding of the chapter to the students and can be downloaded in PDF format. These important question bank help students in clearing their doubts so that they can score well in the exam.
While preparing for exams, students should practise these important questions of Class 10 Science to understand the concepts better. Solving important questions of Class 10 Science Chapter 10 will teach students time management skills and enhance their problem-solving skills. Also, students may come across a few of these questions in the board exam.
1. What is the magnification of the images formed by plane mirrors and why?
Answer: The magnification of the images formed by plane mirrors is 1 as the size of the image is equal to the size of object.
2. An object is placed at a distance of 30 cm from a concave lens of focal length 15 cm. List four characteristics (nature, position, etc.) of the image formed by the lens.
Answer: (a) The image of given object formed by the given concave lens is (i) virtual, (ii) erect, (iii) diminished in size, and (iv) is formed on same side of lens at a distance less than 15 cm from the lens.
3. Write two different uses of concave mirror.
Answer: (i) In solar furnace (ii) In shaving mirror.
4. Define power of a lens.
Answer: The ability of lens to converge or diverge the ray of light is called power of lens. It is equal to the reciprocal of focal length, i.e., P = 1/f
5. Name the mirror that is used by a dentist in examining teeth.
Answer: Dentist uses a concave mirror to See large images of the teeth of patients.
6. What is lateral displacement of a light ray passing through a glass slab?
Answer: The shifting of the light ray sideways (though in the direction of original ray) on emergence from a rectangular glass slab is called “lateral displacement”.
7. Define power of a lens and write its SI unit.
Answer: Reciprocal of focal length of a lens, expressed in metre, is called the power of that lens. Its SI unit is 1 dioptre (1 D), where 1 D = 1 m -1 .
8. Name the lens which can be used as a magnifying glass.
Answer: A convex lens can be used as a magnifying glass so as to form magnified image of a tiny object placed near it.
9. Which type of lens has a negative power?
Answer: A concave (diverging) lens has a negative power.
10. What is the difference between virtual image of an object formed by a convex lens and that formed by a concave lens?
Answer: ‘Virtual image formed by a convex lens is always magnified but that formed by a concave lens is diminished one.
11. During its passage from one medium to another, where does a light ray change its path?
Answer: During its passage from one medium to another a light ray changes its path at the boundary face separating the two media.
12. The power of a lens is + 5 D. Find its focal length in metres.
Answer: Focal length, f = 1/P = +1/5 m = 0.2m
13. What is the difference between virtual images produced by concave, plane and convex mirrors?
Answer: The virtual image formed by concave mirror is magnified, that produced by plane mirror is of the same size and that by a convex mirror is diminished.
14. For driving a car what type of mirror would you prefer to see the traffic at your back and why? Explain why it is preferred over a plane mirror?
Answer: A convex mirror is used to see the traffic at the back. It is because a convex mirror always forms an erect though diminished image of the object. It has a wider field of view. So, we will be able to much larger at the back than a plane mirror while driving the car.
15. An erect image three times the size of the object is formed with a concave mirror of radius of curvature 36 cm. What is the position of the image?
Answer: For an erect image, magnification is positive. Thus, m = 3 for an erect image three times the size of the object.
16. Discuss the position and nature of the image formed by a concave mirror when the object is moved from infinity towards the pole of mirror.
Answer: As the object is moved from infinity towards the pole of a concave mirror, the image formed starts shifting from the focus of the mirror towards infinity.
When the object is at infinity, the image is formed at the focus or in the focal plane. As the object is shifted, the image is formed between the focus and the centre of curvature, then at the centre of curvature, then beyond the centre of curvature, then at infinity and finally the image is formed behind the mirror.
17. Find the position, nature and size of the image of an object 3 cm high place at a distance of 9 cm from a concave mirror of focal length 18 cm.
18. With the help of ray diagrams, show the formation of image of an object by a concave mirror. When it is placed: (i) beyond the centre of curvature (ii) at the centre of curvature.
Answer: (i) When object is beyond the centre of curvature
(ii) When the object is at the centre of curvature
19. A student, holding a mirror in his hand, directed the reflecting surface of the mirror towards the sun. He then directed the reflected light on to a sheet of paper held close to the mirror. (a) What should he do to burn the paper? (b) Which type of mirror does he use? (c) Will he be able to determine the approximate value of focal length of this mirror from this activity? Give reason and draw ray diagram to justify your answer in this case.
Answer: (a) The student should adjust the distance between the mirror and the paper so that solar rays are sharply focussed on the paper. (b) The mirror is a concave mirror. (c) The student can find the approximate focal length by measuring the distance between the paper and the mirror.
As shown in Fig. 10.29, parallel rays from the sun are focussed on the paper at point A’ in focal plane of mirror such that PB’ = f.
20. A concave mirror has a focal length of 20 cm. At what distance from the mirror should a 4 cm tall object be placed so that it forms an image at a distance of 30 cm from the mirror? Also calculate the size of the image formed.
Answer: Given, focal length of concave mirror f = — 20 cm, height of object h o = + 4 cm and distance of image v = 30 cm. Following two cases may arise here:
Case I: If the image formed is real then v = — 30 cm
So, from mirror formula we have
So, the object be placed 60 cm in front of mirror and image is an inverted image of size 2 cm.
Case II: If the image formed is virtual then v = + 30 cm and now
So, the object is placed at 12 cm in front of mirror and image is an erect image of height 10 cm.
21. A 10 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 12 cm. The distance of the object from the lens is 18 cm. Find the nature, position and size of the image.
Answer: As per question f = + 12 cm, u = – 18 cm and h o = + 10 cm As per lens law, we have
The image is formed on opposite side of lens at a distance of 36 cm from it. The image is a real and inverted image.
Moreover, magnification
So, the size of image is 20 cm tall and is formed below the principal axis.
22. A 5 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 30 cm. Find the (i) position, (ii) nature, and (iii) size of the image formed. [CBSE 2004, 2006, 2014, 2019]
Answer: Here h o = + 5 cm, f= + 20 cm, u = – 30 cm (i) Using lens formula we have
(ii) +ve sign of v means that image is being formed on the other side of lens i.e., the image is a real image.
23. A real image, 2/3 rd of the size of an object, is formed by a convex lens when the 3 object is at a distance of 12 cm from it. Find the focal length of the lens.
24. Draw a ray diagram to show refraction through a rectangular glass slab. How is the emergent ray related to incident ray? What is its lateral displacement?
Answer: A ray diagram showing refraction through a rectangular glass slab has been shown in adjoining Fig. 10.32.
The emergent ray GH is exactly parallel to the incident ray EFNM. It means that ∠r 2 = ∠i 1 . However, the emergent ray is laterally (side ways) displaced as compared to the original path of light ray. In ray diagram, the lateral displacement is GN. Its value increases on increasing the width of glass slab.
25. State the laws of refraction of light. Explain the term absolute refractive index of a medium and write an expression to relate it with the speed of light in vacuum.
Answer: Two basic laws of refraction of light are: (i) The incident ray, the refracted ray and the normal to the separating surface at the point of incidence, all lie in the same plane. (ii) The ratio of sine of the angle of incidence to the sine of angle of refraction (r) is a constant. It is known as Snell’s law. Thus, according to Snell’s law
Generally, the constant n is known as the absolute refractive index of given medium. Thus, absolute refractive index of a medium is defined as the ratio of sine of angle of incidence of a light ray in air (or vacuum) to the sine of angle of refraction of the ray in given medium. Absolute refractive index of a medium is a unitless quantity and its value is one or greater than one In terms of speed of fight, the absolute refractive index of a medium is defined as:
26. What is meant by power of a lens? Write its SI unit. A student uses a lens of focal length 40 cm and another of – 20 cm. Write the nature and power of each lens.
27. What is meant by power of a lens? Write its SI unit. A student uses a lens of focal length 40 cm and another of -20 cm. Write the nature and power of each lens.
Answer: Power of a Lens: The ability of a lens to converge or diverge the ray of light after refraction, is called power (P) of the lens. It is defined as the reciprocal of the focal length, i.e. P = 1/f. The SI unit of power of a lens is ‘dioptre’. A lens of focal length 100 cm has a power of 1 dioptre = 1 m -1 . Given: f A = + 40 cm = 0.4 m, f B = -20 cm
Hence, the nature of lens A is convex with power + 2.5D and lens B is concave with power -5D.
28. What is mean by power of lens? You have three lenses L 1 , L 2 and L 3 of power +10 D, +5 D and – 10 D respectively. State the nature and focal length of each lens. Explain which of the three lenses will from a virtual and magnified image of an object placed at 15 cm from the lens. Draw the ray diagram in support of your answer.
Answer: Power of lens: It is the degree of convergence or divergence of light rays after refraction through a spherical lens is called power of lens. It is the reciprocal of its focal length.
When object is placed between focus and optical centre of convex lens, virtual erect and magnified image is formed on the same side of the lens. Hence, for the object distance of 15 cm, lens L 2 will form the same.
29. We wish to obtain an equal sized inverted image of a candle flame on a screen kept at distance of 4 m from the candle flame. (a) Name the type of lens that should be used. (b) What should be the focal length of the lens and at what distance from the candle flame the lens be placed. (c) Draw a labelled diagram to show the image formation in this case.
Answer: (a) Convex lens. (b) 2F = 4 ⇒ f = 2 m Distance of candle flame from the lens = 4 m.
30. If the image formed by a mirror for all positions of the object placed in front of it is always erect and diminished, what type of mirror is it? Draw a ray diagram to justify your answer. Where and why do we generally use this type of mirror?
Answer: Only a convex mirror always form an erect and diminished image behind the mirror between its pole and focus point for all positions of the object placed in front of the mirror.
A ray diagram showing the image formation of an object AB is shown here. A convex mirror is used as a rear view mirror in automobiles because it gives erect and diminished images of vehicles coming from behind. As a result, it helps the driver in having a much wider field of view.
31. An object 4 cm in height, is placed at 15 cm in front of a concave mirror of focal length 10 cm. At what distance from the mirror should a screen be placed to obtain a sharp image of the object. Calculate the height of the image.
Answer: Here distance of object u = – 15 cm, height of object h o = + 4 cm and the focal length of concave mirror f = – 10 cm.
As per mirror formula we have
32. The magnification of an image formed by a lens is -1. If the distance of the image from the optical centre of the lens is 25 cm, where is the object placed? Find the nature and focal length of the lens. If the object is displaced 15 cm towards the optical centre of the lens, where would the image be formed? Draw a ray diagram to justify your answer.
Thus, the positive focal length shows that the given lens is a convex lens of focal length 12.5 cm. If the object is now displaced 15 cm towards the optical centre of the lens i.e, object is now placed at a distance of 25 – 15 = 10 cm from the optical centre. Therefore u = – 10 cm, and f = +12.5 cm.
So, in this case, virtual image is formed on the same side of the object at a distance of 50 cm from the optical centre of the lens as shown in figure
33. If the image formed by a lens for all positions of an object placed in front of it is always erect and diminished, what is the nature of this lens? Draw a ray diagram to justify your answer. If the numerical value of the power of this lens is 10 D, what is its focal length in the Cartesian system?
34. Define the term magnification as referred to spherical mirrors. If a concave mirror forms a real image 40 cm from the mirror, when the object is placed at a distance of 20 cm from its pole, find the focal length of the mirror.
Answer: Magnification of spherical mirror (m): It is equal to the ratio of size (height) of the image to the size (height) of the object. Thus,
35. State Snell’s law of refraction of light. Express it mathematically. Write the relationship between absolute refractive index of a medium and speed of light in vacuum.
36. Draw ray diagrams to show the principal focus of a (i) concave mirror (ii) convex mirror.
Answer: Ray diagrams have been shown in following Figs. 10.11(a) and (b) respectively.
37. Complete the following diagram [Fig. 10.12]
Answer: The completed diagram is as given above in Fig. 10.13.
38. Define optical centre of a spherical lens.
Answer: Optical centre of a spherical lens is a point on its principal axis, a ray of light passing through which goes undeviated along its path after refraction.
39. Draw the following diagram [Fig. 10.22], in which a ray of light is incident on a concave/convex mirror, on your answer sheet. Show the path of this ray, after reflection, in each case.
Answer: The diagrams have been drawn and path of rays after reflection have been shown:
40. State two positions in which a concave mirror produces a magnified image of a given object. List two differences between the two images.
Answer: Two positions in which a concave mirror produces a magnified image are : (i) When an object is placed between focus point F and centre of curvature C of the mirror. For this position the image is real, inverted and magnified, and the image is formed beyond centre of curvature of the mirror. (ii) When an object is placed between pole P and focus point F of the mirror. For this position the image is virtual, erect and magnified and the image is formed behind the mirror.
41. It is desired to obtain an erect image of an object, using concave mirror of focal length of 12 cm. (i) What should be the range of distance of an object placed in front of the mirror? (ii) Will the image be smaller or larger than the object? Draw ray diagram to show the formation of image in this case. (iii) Where will the image of this object be, if it is placed 24 cm in front of the mirror? Draw ray diagram for this situation also to justify your answer.
Answer: It is given that focal length of concave mirror is 12 cm. (i) To obtain an erect image of an object by this mirror, the object should be placed in front of the mirror between its pole and focus point, that is |u| < 12 cm.
(ii) The image is larger than the object. The ray diagram has been shown in Fig. 10.25.
(iii) If object be placed at 24 cm in front of the mirror then it means that the object is situated at the centre of curvature [ ∵ | u | = 24 cm = 2f – 2 x 12 cm = R ] C of the given mirror. Hence as shown in Fig. 10.24 the real, inverted image of same size is formed at centre of curvature C itself [ |v| = 24 cm].
42. (a) Draw a ray diagram to show the formation of image by a convex lens when an object is placed in front of the lens between its optical centre and principal focus. (b) In the above ray diagram mark the object-distance (u) and the image distance (v) with their proper signs (+ve or -ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f) of the convex lens in this case.
Answer: (a) The ray diagram is as shown in Fig. 10.37.
(b) The object distance ‘u’, the image distance ‘v’ and the focal length ‘f’ of the convex lens are correlated as per relation:
While applying this formula we must specify +ve or -ve signs of u, v and f as per new Cartesian sign convention being followed.
43. Find the power of a convex lens which forms a real, and inverted image of magnification -1 of an object placed at a distance of 20 cm from its optical centre.
Answer: Here u = – 20 cm and magnification m = – 1 for real and inverted image ∵ m = v/u, hence v = mu = (-1) × (-20) = + 20 cm
44. A divergent lens has a focal length of 20 cm. At what distance should an object of height 4 cm from the optical centre of the lens be placed so that its image is formed 10 cm away from the lens. Find the size of the image also. Draw a ray diagram to show the formation of image in above situation.
Answer: Here focal length of given divergent (concave) lens f = – 20 cm, height of the object h = + 4 cm and distance of image from the lens v = 10 cm. As the image formed by a concave lens is always virtual and erect, hence as per sign convention u = – 10 cm.
As per lens formula we have
Thus, the object is placed at a distance 20 cm from the lens. Moreover
A ray diagram to show the formation of image is given here in Fig. 10.39.
45. The image of an object formed by a mirror is real, inverted and is of magnification -1. If the image is at a distance of 40 cm from the mirror, where is the object placed? Where would the image be if the object is moved 20 cm towards the mirror? State reason and also draw ray diagram for the new position of the object to justify your answer.
Answer: Given: Magnification of spherical mirror = -1, Image distance, v = -40 cm Magnification,
Therefore, the object is placed at a distance of 40 cm in front of the spherical mirror.
Case I: when u = -40 cm and v = -40 cm, Using mirror formula, we get
Hence the focal length of the mirror is 20 cm, and the negative focal length shows that it is a concave mirror. The new position of the object when it moves 20 cm towards the concave mirror, u’ = – (40 – 20) = -20 cm. Case II: u’ = – 20 cm, f = – 20 cm, v =?
From mirror formula,
Thus, the image is formed at infinity. Hence when the object is moved 20 cm towards the mirror, a real, inverted and highly enlarged image is formed at infinity.
46. If the image formed by mirror for all positions of the object placed in front of it is always virtual and diminished, state the type of the mirror. Draw a ray diagram in support of your answer. Where are such mirrors commonly used and why?
Answer: Convex Mirror
A convex mirror is commonly used as a rear-view mirror in vehicles because it always produces a virtual and erect image whose size is smaller than the object. Therefore, it enables the driver to see a wide field of view of the traffic behind the vehicle in a small mirror. 47. If the image formed by a lens for all positions of the object placed in front of it is always virtual, erect and diminished, state the type of the lens. Draw a ray diagram in support of your answer. If the numerical value of focal length of such a lens is 20 cm, find its power in new cartesian sign conventions.
Answer: Concave lens (i) When an object is placed at infinity. (ii) When an object is placed between F 1 and 2F 1
Thus, from the above figures, it is clear that whatever be the position of the object in front of a concave lens, the image formed is always virtual, erect and diminished. The power of the given lens is calculated as
48. To construct a ray diagram we use two rays of light which are so chosen that it is easy to determine their directions after reflection from the mirror. Choose these two rays and state the path of these rays after reflection from a concave mirror. Use these two rays to find the nature and position of the image of an object placed at a distance of 15 cm from a concave mirror of focal length 10 cm.
Answer: The position of the image formed by a spherical mirror can be found by considering following two rays: (i) The ray incident parallel to the principal axis, after reflection, passes through the principal focus of a concave mirror. (ii) A ray passing through the centre of curvature in a concave mirror after reflection, retraces its path.
The image formation is shown in the above figure. Here for every 5 cm distance we have 1 cm in the ray diagram. Here AB is the object and ATT is the real and inverted image formed on the basis of above mentioned two rays. Actual measurement shows that the image is formed 30 cm in front of the concave mirror i.e., v = 30 cm.
49. (a) Define optical centre of a lens. What happens when a ray of light passes through the optical centre of lens? (b) Define principal focus and focal length of a lens. Draw ray diagram to show the position of principal focus of a lens.
Answer: (a) The optical centre of a thin lens is a point on its principal axis, a ray of light passing through which goes straight without any bending (or deviation). In Fig. 10.33, the point O is the optical centre.
(b) Principal focus of a lens is a point where a light beam incident parallel to the principal axis of the lens, after refraction, actually converges to (in case of a convex lens) or diverges from (in case of a concave lens). Since, a lens has two refracting surfaces, a lens has two principal foci. F 1 and F 2 on either side of lens.
The distance of principal focus of a lens from its optical centre is called its focal length f. Thus, f = OF 1 = OF 2 .
50. A student wants to project the image of a candle flame on a screen 80 cm in front of a mirror by keeping the candle flame at a distance of 20 cm from its pole. (i) Which type of mirror should the student use? (ii) Find the magnification of the image produced. (iii) Find the distance between the object and its image. (iv) Draw a ray diagram to show the image formation in this case and mark the distance between the object and its image.
Answer: (i) Concave mirror, as it forms a real image on the same side of the mirror.
(iii) Distance between the object and its image = 80 – 20 = 60 cm
(iv) The focal length of the concave mirror is given by
Since u = – 20 cm, it implies that the object lies between F and C, so image is formed beyond the centre of curvature as shown below:
The image is real, inverted and enlarged.
51. Draw a ray diagram to show the path of the reflected ray in each of the following cases. A ray of light incident on a convex mirror. (a) strikes at its pole making an angle θ from the principal axis. (b) is directed towards its principal focus. (c) is parallel to its principal axis.
52. An object of height 5 cm is placed perpendicular to the principal axis of a concave lens of focal length 10 cm. If the distance of the object from the optical centre of the lens is 20 cm, determine the position, nature and size of the image.
Answer: Given: h o = + 5 cm, f = – 10 cm, u = – 20 cm, v = ?, h i =?
Using lens formula, web have
So, the image is formed on the same side of the object at a distance of 6.67 cm. The negative sign indicates that the image is virtual. Also |u|< |u| so the image is diminished.
So, the image is virtual, erect, diminished and of size 1.66 cm.
53. An object is placed at a distance of 60 cm from a concave lens of focal length 30 cm. (i) Use lens formula to find the distance of the image from the lens. (ii) List four characteristics of the image (nature, position, size, erect/inverted) formed by the lens in this case. (iii) Draw ray diagram to justify your answer of part (ii).
Answer: Given u = – 60 cm, f = – 30 cm (i) Using lens formula,
(ii) Nature of image: Virtual Position of image: Between optical centre and focus of concave lens. Size of image: Smaller than the object using
So, size of image is one third of the object. Erect/inverted: Erect image
54. (a) List four characteristics of the image formed by a convex lens when an object is placed between its optical centre and principal focus. (b) Size of the image of an object by a concave lens of focal length 20 cm is observed to be reduced to 1/3 rd of its size. Find the distance of the object from the lens.
Answer: (a) When an object is placed between the optical centre and principal focus of a convex lens, the image formed is virtual, erect and enlarged. Moreover, the image is formed on the same side of lens behind the object.
(b) Here magnification of given concave lens m = +1/3 and focal length of lens f = – 20 cm. As per relation m = v/u for a lens, we get
Therefore, as per sign convention followed, both u and v are -ve.
Using lens formula we have
So, the object is placed at a distance of 40 cm from the lens.
55. (a) What is the minimum number of rays required for locating the image formed by a concave mirror for an object? Draw a ray diagram to show the formation of a virtual image by a concave mirror. (b) The linear magnification produced by a spherical mirror is+3. Analyse this value and state the (i) type of mirror and (ii) position of the object with respect to the pole of the mirror. Draw ray diagram to show the formation of image in this cased (c) An object is placed at a distance of 30 cm in front of a convex mirror of focal length 15 cm. Write four characteristics of the image formed by the mirror.
Answer: (a) Two rays are required.
(b) The linear magnification produced by a spherical mirror is +3. It shows that the size of image is three times the size of object, image is virtual and erect and formed behind the mirror. Hence
(i) the mirror is a concave mirror, and (ii) the object is placed between the pole and the focus of a concave mirror.
(c) The four characteristics of the image formed by the convex mirror are virtual, erect, diminished and laterally inverted.
56. (a) To construct a ray diagram we use two rays which are so chosen that it is easy to know their directions after reflection from the mirror. List two such rays and state the path of these rays after reflection in case of concave mirrors. Use these two rays and draw ray diagram to locate the image of an object placed between pole and focus of a concave mirror. (b) A concave mirror produces three times magnified image on a screen. If the object is placed 20 cm in front of the mirror, how far is the screen from the object?
Answer: (a) Rays which are chosen to construct a ray diagram for reflection are: O’) A ray parallel to the principal axis and a ray passing through the centre of curvature of a concave mirror. Path of these light rays after reflection: (i) It will pass through the principal focus of a concave mirror (ii) It gets reflected back along the same path. When an object is placed between the pole and the principal focus of a concave mirror, a virtual, erect and enlarged image is formed behind the concave mirror as shown in the figure.
57. (a) If the image formed by a mirror for all positions of the object placed in front of it is always diminished, erect and virtual, state the type of the mirror and also draw a ray diagram to justify your answer. Write one use such mirrors are put to and why? (b) Define the radius of curvature of spherical mirrors. Find the nature and focal length of a spherical mirror whose radius of curvature is +24 cm.
Answer: (a) Convex (diverging) mirror view mirror.
Reason: (i) It always produces a virtual and erect image. (ii) The size of image formed is smaller than the object.
Therefore, it enables the driver to see a wide field view of the traffic behind the vehicle in a small mirror. (b) Radius of Curvature: The separation between the pole and the centre of curvature or the radius of the hollow sphere, of which the mirror is a part, is called radius of curvature (R), i.e., PC = R.
Since focal length of the mirror is +24 cm. It indicates that nature of the given spherical mirror is convex/diverging mirror. As R = 2f = 24 cm Therefore, f = +12 cm 58. (a) Draw labelled ray diagrams for each of the following cases to show the position, nature and size of the image formed by a convex lens when the object is placed. (i) between its optical centre (O) and principal focus (F) (ii) between F and 2 F (b) How will the nature and size of the image formed in the above two cases, (i) and (ii) change, if the convex lens is replaced by a concave lens of same focal length?
Answer: A convex lens of focal length ‘f’ can form (i) a magnified and erect image only when the object is placed between its focus ‘F’ and optical centre ‘O’ of the lens.
(ii) a magnified and inverted image when an object is placed in the following positions: Between F 1 and 2F 1
(b) Whatever be the position of object as given in case (i) and (ii), the image formed by the concave lens is always virtual, erect and diminished. 59. State the laws that are followed when light is reflected by spherical mirrors. Daw a ray diagram to show the formation of image of an object placed infront of a convex mirror. List two characteristics of the image formed. Briefly explain one use of convex mirror.
Answer: The two laws of reflection of light are: (i) The angle of incidence is equal to the angle of reflection. (ii) The incident ray, the normal to the reflecting surface at the point of incidence and the reflected ray from that point, all lie in the same plane. (i) Image formed is behind the mirror between pole (P) and focus (F). (ii) Virtual, erect and diminished image is formed.
(ii) Rear-view mirror of vehicles: Convex mirror Convex mirror is used because it always produces a virtual and erect image whose size is smaller than the object. Therefore, it enables the driver to see wide field view of the traffic behind the vehicle in a small mirror.
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The concept of light, reflection, and refraction is quite fascinating for the students of Class 10. In the previous classes, students have learned a lot of new things related to these two natural phenomena occurring with light. In Class 10, they will advance to a new level of concepts related to reflection and refraction. The textbook explains the concepts pretty well. Students will need more Light Reflection and Refraction Class 10 Important Questions with answers to prepare for the exams.
By studying the Class 10 Science Chapter 10 Important Questions, you will develop your concept for this chapter in a better way. In fact, your answering skills will also increase considerably. Check out how the expert teachers at Vedantu have answered the Light Class 10 Important Questions niftily. Download the PDF and follow the format of answering questions as shown by the experts to score more. Vedantu is a platform that provides free CBSE Solutions (NCERT) and other study materials for students. Maths Students who are looking for the better solutions, they can download Class 10 Maths NCERT Solutions to help you to revise complete syllabus and score more marks in your examinations.
Also, check CBSE Class 10 Science Important Questions for other chapters:
CBSE Class 10 Science Important Questions | ||
Sl.No | Chapter No | Chapter Name |
1 | Chapter 1 |
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2 | Chapter 2 |
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3 | Chapter 3 |
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4 | Chapter 4 |
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5 | Chapter 5 |
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6 | Chapter 6 |
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7 | Chapter 7 |
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8 | Chapter 8 |
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9 | Chapter 9 |
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10 | Chapter 10 | Light Reflection and Refraction |
11 | Chapter 11 |
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12 | Chapter 12 |
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13 | Chapter 13 |
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14 | Chapter 14 |
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15 | Chapter 15 |
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16 | Chapter 16 |
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The following list of important topics covered under the chapter on Light Reflection and Refraction has been provided for students so that they can take a glance at the major concepts and read them through before diving into the important questions.
Reflection of Light
Spherical Mirrors
Image Formation by Spherical Mirrors
Sign Convention for Spherical Mirrors
Mirror Formula and Magnification
Refraction of Light
Refraction through a Rectangular Glass Slab
Refractive Index
Refraction by Spherical Lenses
Image Formation by Lenses and Their Ray Diagrams
Sign Convention for Spherical Lenses
Lens Formula and Magnification
Power of a Lens
Long Answer Questions (5 Marks)
1. A convex lens has a focal length of \[10\] cm. At what distance from the lens should the object be placed so that it forms a real and inverted image $20$ cm. away from the lens? What would be the size of the image formed if the object is $2$ cm high? With the help of a ray, the diagram shows the formation of the image by the lens in this case?
Ans: Given, the focal length of the convex lens,
$\Rightarrow f=+10$ cm
Also, given the image formed is real and inverted with the image distance as $20$ cm.
$\Rightarrow v=+20$ cm
From the lens formula, we have:
$\Rightarrow \dfrac{1}{f}=\dfrac{1}{v}-\dfrac{1}{u}$
$\Rightarrow \dfrac{1}{10}=\dfrac{1}{20}-\dfrac{1}{u}$
$\Rightarrow \dfrac{1}{u}=\dfrac{1}{20}-\dfrac{1}{10}$
$\Rightarrow \dfrac{1}{u}=\dfrac{-1}{20}$
$\Rightarrow u=-20$ cm.
$\therefore $ The object is placed at a distance of $20$ cm.
Magnification is given as,
$\Rightarrow m=-\dfrac{v}{u}$
$\Rightarrow m=-\dfrac{20}{\left( -20 \right)}$
$\Rightarrow m=+1$
Also, magnification is given by, $m=\dfrac{Height\text{ of the image}}{Height\text{ of the object}}$.
$\therefore m=\dfrac{Height\text{ of the image}}{2}$
$\Rightarrow 1=\dfrac{Height\text{ of the image}}{2}$
$\Rightarrow Height\text{ of the image}=2$ cm.
Thus, the image is of the same size as that of the object and it is real and inverted.
The ray diagram representing the formation of the image by the lens in this case is:
It is observed that the image is formed at $2{F_2}$ with the object placed at $2{F_1}$.
2. Draw a ray diagram to show the use of a convex lens for the formation of images having the following characteristics.
a. Real & inverted and diminished
Ans: A ray diagram representing a real & inverted and diminished image is given below.
b. Virtual, erect & magnified.
Ans: A ray diagram representing a virtual, erect, and magnified image is given below.
3. A convex lens forms a real and inverted image of a needle at a distance of $50$ cm. from it. Where is the needle placed in front of the convex lens if the image is equal to the size of objects? Also, find the power of the lens.
Ans: Given, the image is real and inverted at a distance of $50$ cm.
$\Rightarrow v=+50$ cm
Also given, Height of image $=$ Height of object
We know, magnification is given as,
$\therefore -\dfrac{v}{u}=\dfrac{Height\text{ of the image}}{Height\text{ of the object}}$
Since, Height of image $=$ Height of object and $v=+50$ cm
$\Rightarrow -\dfrac{50}{u}=1$
$\Rightarrow u=-50$ cm
$\Rightarrow \dfrac{1}{f}=\dfrac{1}{50}-\dfrac{1}{-50}$
$\Rightarrow f=25$ cm
$\Rightarrow f=0.25$ m
The power of a lens is given by,
$\Rightarrow P=\dfrac{1}{f}$
$\Rightarrow P=\dfrac{1}{0.25}$ m
$\Rightarrow P=+4$ D
4. One-half of a convex lens is covered with black paper. Will this lens produce a complete image of the object? Verify your answers experimentally. Explain your observations.
Ans: If we cover one-half of a convex lens with black paper it is observed that it produces a complete image of the object.
Representing the given situation with a ray diagram.
Adjust the position of the burning candle such that its image is formed on the screen placed on the other side of the lens.
We get a full image of the burning candle on the screen.
Thus, from the above observation, we conclude that the formation of an image does not depend on the length of the lens, but the brightness of the image formed on the screen depends since the number of rays passing through the lens gets reduced on covering half the lens with black paper.
5. An object $5$ cm in length is held $25$ cm away from a converging lens of focal length $10$ cm. Draw the ray diagram and find the position, size, and nature of the image formed.
Ans: Given focal length of the lens, $f=+10$ cm.
Object distance from the converging lens is given to be $25$ cm and the height of the object ($ho$) is given to be $5$ cm.
$\Rightarrow u=-25$ cm
$\Rightarrow ho=5$ cm
$\Rightarrow \dfrac{1}{10}=\dfrac{1}{v}-\dfrac{1}{-25}$
$\Rightarrow \dfrac{1}{v}=\dfrac{1}{25}-\dfrac{1}{10}$
$\Rightarrow v=\dfrac{50}{3}$ cm
$\Rightarrow v=16.7$ cm
Thus, we conclude that the image formed is real and inverted and is formed at a distance of $16.7$ cm on the other side of the lens.
Also, magnification is given by, $m=\dfrac{Height\text{ of the image}}{Height\text{ of the object}}=\dfrac{hi}{ho}$.
$\therefore -\dfrac{v}{u}=\dfrac{hi}{ho}$
$\Rightarrow \dfrac{16.7}{-25}=\dfrac{hi}{5}$
$\Rightarrow hi=-\dfrac{10}{3}$ cm
Hence, the image is diminished.
The ray diagram representing the above situation is drawn below.
6. A convex lens of focal length $15$ cm formed an image $10$ cm from the lens. How far is the object placed from the lens? Draw the ray diagram.
Ans: Given focal length of the lens, $f=15$ cm.
Image distance from the converging lens is given to be $10$ cm.
$\Rightarrow v=-10$ cm
We observe that the image distance is less than the focal length, hence the image formed would be virtual and erect.
$\Rightarrow \dfrac{1}{15}=\dfrac{1}{-10}-\dfrac{1}{u}$
$\Rightarrow \dfrac{1}{u}=-\dfrac{1}{10}-\dfrac{1}{15}$
$\Rightarrow u=-6$ cm
light rays, mirrors, lenses, prisms, etc., is the advanced version of what you As mentioned earlier, the chapter related to light, reflection, and refraction of have studied in the previous classes. In Class 10, you will have to focus on the theoretical part, as well as, the use of these theories to answer questions.
After you have completed answering the basic questions in the exercise, you might need a question bank to learn more about this chapter. This is where Light Reflection and Refraction Class 10 Important Questions with Answers can be used perfectly. These questions will intellectually challenge your knowledge and foundation of concepts based on this topic. You can answer on your own and check whether you know the right answer or not.
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The Important Questions of Light Reflection and Refraction Class 10 is the ultimate suggestion for the upcoming board exam. You can study these questions, prepare their answers on your own, and compare them with the solution provided. This will help you to understand how efficiently you have studied the chapter. Light Class 10 Important Questions have been developed to help you think out of the box. In most cases, the thoughts of the students remain stuck in the exercises of the textbook. These questions will help them think out of the box and challenge their intellect.
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You can download Chapter 10 Science Class 10 Important Questions and solutions in PDF format and study them offline. Get this extra set of questions and use them as a reference to clear your concepts of this crucial chapter.
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1. Why Should You Prefer Vedantu for Important Questions of Light Class 10?
The teachers of Vedantu have formulated the best possible questions of Class 10 Light for the students to follow. The answers are simple and follow the CBSE guidelines. You can rest be assured that you will get the best-quality questions and answers to study.
2. Why Should You Study Light Reflection and Refraction Important Questions?
By studying the Light Reflection and Refraction Class 10 Important Questions, you will get a good idea of what questions are asked in the board exam. Follow the answering style and score more in the main exam.
3. What are the important topics covered in the CBSE Class 10 Science Chapter 10 - Light Reflection and Refraction?
The following are the important topics covered in the Chapter on Light Reflection and Refraction:
Cbse study materials.
NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12
September 27, 2019 by Veerendra
NCERT Solutions For Class 10 Science Chapter 10 Light Reflection and Refraction : In this article, you candidates can find light reflection and refraction class 10 NCERT solutions. Working on the light chapter of class 10 NCERT solutions will help candidates to build a strong foundation over the subject Physics. Knowing light reflection and refraction class 10 questions and answers will help students of class 10 to bag a decent score in class 10 board exams as well.
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Free download NCERT Solutions for Class 10 Science Chapter 10 Light Reflection and Refraction PDF in Hindi Medium as well as in English Medium for CBSE, Uttarakhand, Bihar, MP Board, Gujarat Board, and UP Board students, who are using NCERT Books based on updated CBSE Syllabus for the session 2019-20.
Ncert solutions for class 10 science chapter 10 intext questions.
Page Number: 168
Question 1 Define the principal focus of a concave mirror. Answer: The principal focus of a concave mirror is a point on its principal axis to which all the light rays which are parallel and close to the axis, converge after reflection from the concave mirror.
Question 2 The radius of curvature of a spherical mirror is 20 cm. What is its focal length? Answer: Focal length = \(\frac { 1 }{ 2 }\) x Radius of curvature = \(\frac { 1 }{ 2 }\) x 20 cm = 10 cm
Question 3 Name a mirror that can give an erect and enlarged image of an object. Answer: Concave mirror.
Question 4 Why do we prefer a convex mirror as a rear-view mirror in vehicles ? Answer: We prefer a convex mirror as a rear-view mirror in vehicles because of two reasons :
Page Number: 171
Question 1 Find the focal length of a convex mirror whose radius of curvature is 32 cm. Solution: R = +32 cm and \(f=\frac { R }{ 2 } =+\frac { 32 }{ 2 } =+16cm\)
Page Number: 176
Question 1 A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or away from the normal ? Why ? Answer: The light-ray bends towards the normal because the ray of light goes from a rarer medium to a denser medium.
Question 3 Find out, from Table 10.3, the medium having highest optical density. Also find the medium with lowest optical density. Answer: From table 10.3, diamond has highest refractive index (= 2.42), so it has highest optical density. Air has lowest refractive index (= 1.0003), so it has lowest optical density.
Question 4 You are given kerosene, turpentine and water. In which of these does the light travel fastest ? Use the information given in Table 10.3. Answer: For kerosene, n = 1.44 For turpentine, n = 1.47 For water, n = 1.33 Because water has the lowest refractive index, therefore light travels fastest in this optically rarer medium than kerosene and turpentine oil.
Question 5 The refractive index of diamond is 2.42. What is the meaning of this statement? Answer: By saying that the refractive index of diamond is 2.42, we mean that the speed of light in diamond is lower by a factor of 2.42 relative to that in vacuum.
Page Number: 184
Question 1 Define 1 dioptre of power of a lens. Answer: One dioptre is the power of a lens whose focal length is 1 metre.
Question 1 Which one of the following materials cannot be used to make a lens ? (a) Water (b) Glass (c) Plastic (d) Clay Answer: (d) Clay
Question 2 The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object ? (a) Between the principal focus and the centre of curvature (b) At the centre of curvature (c) Beyond the centre of curvature (d) Between the pole of the mirror and its principal focus. Answer: (d) Between the pole of the mirror and its principal focus.
Question 3 Where should an object be placed in front of a convex lens to get a real image of the size of the object ? (a) At the principal focus of the lens (b) At twice the focal length (c) At infinity (d) Between the optical centre of the lens and its principal focus. Answer: (b) At twice the focal length.
Question 4 A spherical mirror and a thin spherical lens have each a focal length of -15 cm. The mirror and the lens are likely to be : (a) Both concave. (b) Both convex. (c) the mirror is concave and the lens is convex. (d) the mirror is convex, but the lens is concave. Answer: (a) Both concave
Question 5 No matter how far you stand from mirror, your image appears erect. The mirror is likely to be (a) plane (b) concave (c) convex (d) either plane or convex. Answer: (d) Either plane or convex.
Question 6 Which of the following lenses would you prefer to use while reading small letters found in a dictionary ? (a) A convex lens of focal length 50 cm. (b) A concave lens of focal length 50 cm. (c) A convex lens of focal length 5 cm. (d) A concave lens of focal length 5 cm. Answer: (c) A convex lens of focal length 5 cm.
Question 8 Name the type of mirror used in the following situations. (a) Headlights of a car. (b) Side/rear-view mirror of a vehicle. (c) Solar furnace. Support your answer with reason. Answer: (a) Concave mirrors are used as reflectors in headlights of cars. When a bulb is located at the focus of the concave mirror, the light rays after reflection from the mirror travel over a large distance as a parallel beam of high intensity.
(b) A convex mirror is used as a side/rear-view mirror of a vehicle because
(c) Large concave mirrors are used to concentrate sunlight to produce heat in solar furnaces.
Question 13 The magnification produced by a plane mirror is +1. What does this mean ? Answer: Since magnification, \(m=\frac { { h }^{ ‘ } }{ h } =\frac { -\nu }{ u }\). Given, m = +1, so h’ = h and ν = -u
(i) m = 1 indicates the size of image is same as that of object. (ii) positive sign of m indicates that an erect image is formed.
The opposite signs of ν and u indicate that image is formed on the other side of the mirror from where the object is placed i.e., image is formed behind the mirror and thus image formed is virtual.
Reflection of light by curved surfaces; Images formed by spherical mirrors, center of curvature, principal axis, principal focus, focal length, mirror formula (Derivation not required), magnification. Refraction; laws of refraction, refractive index. Refraction of light by spherical lens; Image formed by spherical lenses; Lens formula (Derivation not required); Magnification. Power of a lens;
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Formulae Handbook for Class 10 Maths and Science
Question 1. Define the principal focus of a concave mirror? Answer: Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror. This point is known as the principal focus of the concave mirror.
Question 2. The radius of curvature of a spherical mirror is 20 cm. What is its focal length? Answer: Radius of curvature, R = 20 cm Radius of curvature of a spherical mirror = 2 x Focal length (f) f = R/2 = 20/2 =10cm
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Question 3. Name the mirror that can give an erect and enlarged image of an object. Answer: When an object is placed between the pole and the principal focus of a concave mirror, the image formed is virtual, erect, and enlarged.
Download NCERT Solutions for Class 10 Science Chapter 10 Light Reflection and Refraction PDF
Question 4. Why do we prefer a convex mirror as a rear-view mirror in vehicles? Answer: Convex mirrors give a virtual, erect, and diminished image of the objects placed in front of them. They are preferred as a rear-view mirror in vehicles because they give a wider field of view, which allows the driver to see most of the traffic behind him.
Question 1. Find the focal length of a convex mirror whose radius of curvature is 32 cm. Answer: Radius of curvature, R = 32 cm Radius of curvature = 2 x Focal length (f) R = 2f f = R/2 = 32/2 = 16cm Hence, the focal length of the given convex mirror is 16 cm.
Question 2. A concave mirror produces three times magnified (enlarged) real image of object placed at 10 cm in front of it. Where is the image located? Answer: Given, u = – 10 cm Since image is real inverted so, m = -3 m = -v / u ⇒ -3 = -v/ -10 v= – 30 cm Negative sign indicates the image will be real and image is formed at 30 cm in front of the mirror.
Question 1. A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or away from the normal? Why? Answer: The light ray bends towards the normal. When a ray of light travels from an optically rarer medium to an optically denser medium, it gets bent towards the normal. Since water is optically denser than air, a ray of light travelling from air into the water will bend towards the normal.
Question 1. Define one dioptre of power of a lens? Answer: One dioptre is the power Of a lens Of focal length 1m. Power of lens is defined as the reciprocal of its focal length. If P is the power of a lens of focal length F in metres, then P = 1/ f (in meters) The S.I. unit of power of a lens is Dioptre. It is denoted by D. 1 dioptre is defined as the power of a lens of focal length 1 metre. 1 D = 1 m−1
Question 2. A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the lens if the image is equal to the size of the object? Also find the power of the lens. Answer: v = + 50 cm Since image is real and of same size. The position of image should be double the focal length. Hence, the object should be at 2f. V = 2f = 50, f = 25 cm. Power = 1/f = 100/25 = 4D
Question 1. Which one of the following materials cannot be used to make a lens? (a) Water (b) Glass (c) Plastic (d) Clay Answer: (d) Clay
Question 2. The ¡mage formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object? (a) Between the principal focus and the centre of Curvature (b) At the centre of curvature (c) Beyond the centre of curvature (d) Between the pole of the mirror and Its principal focus. Answer: (d) Between the pole of the mirror and its principal focus.
Question 3. Where should an object b. placed In front of a convex lens to get a real image of the size of the object? (a) At the principal focus of the lens (b) At twice the focal length (c) At infinity (d) Between the optical centre of the lens and its principal focus Answer: (b) At twice the focal length
Question 4. A spherical mirror and a thin spherical lens have each a focal length of 15 cm. The mirror and the lens are likely to be: (a) both concave (b) both convex (c) the mirror is concave, but the lens is convex (d) the mirror is convex, but the lens is concave Answer: (a) Both concave.
Question 5. No matter how far you stand from a mirror, your Image appears erect. The mirror is likely to be (a) plane (b) concave (c) convex (d) Either plane or convex Answer: (d) Either plane or convex.
Question 6. Which of the following lenses would you prefer to use while reading small letters found ¡n a dictionary? (a) A convex lens of focal length 50cm (b) A concave lens of focal length 50cm (c) A convex lens of focal length 5 cm (d) A concave lens of focal length 5 cm. Answer: (c) A convex lens of focal length 5 cm.
Question 8. Name the type of mirror used in the following situations. (a) Headlights of a car (b) Side/rear-view mirror of a vehicle (c) Solar furnace Support your answer with reason. Answer: (a) Concave mirror, to get powerful and parallel beams of light. (b) Convex mirror because it always gives an erect image and enables the driver to view much larger area. (c) Concave or parabolic mirror because it can concentrate sunlight at the focus to produce heat in the solar furnace.
Question 9. One half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations. Answer: Yes, even when one half of the lens is covered with a black paper, complete image of the object will be formed. Take a convex lens and focus the light from a distant object onto a screen. As expected an image (sharp) is formed at a distance equal to the focal length Cover the lower or the upper half of the lens and focus the light from the same object onto the same screen. You will be able to get a sharp image again; however the brightness of the image will be less in the second case. The same effect w,ll be seen even if the lens is half covered with black strips.
Question 13. The magnification produced by a plane mirror is +1. What does this mean? Answer: This means that size of the image is equal to the size of the object.
Multiple Choice Questions (MCQs) [1 mark each]
Question 1. Hold a highly polished steel spoon curved inwards close to your face and move it slowly away from your face. What will you observe? (a) Enlarged and erect image of your face (b) Smaller and inverted image of your face (c) Smaller and erect image of your face (d) Enlarged and inverted image of your face Answer: (b) The inner curved surface of a highly polished steel spoon acts as a concave mirror. When the spoon is at a small distance from the face such that, the object lies between pole and focus of concave mirror, so an enlarged and erect image of your face will be observed but as the spoon is slowly moved away from the face, the image becomes smaller and appears inverted.
Question 2. Which one of the following materials cannot be used to make a lens? [NCERT] (a) Water (b) Glass (c) Plastic (d) Clay Answer: (d) Clay can never be transparent, so it cannot be used to make lens.
Question 3. No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be [NCERT] (a) plane (b) concave (c) convex (d) either plane or convex Answer: (d) Plane mirrors and convex mirrors always form the erect images.
Question 4. The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object? [NCERT] (a) Between principal focus and centre of curvature (b) At centre of curvature (c) Beyond centre of curvature (d) Between pole of the mirror and its principal focus Answer: (d)
Question 6. A spherical mirror and a thin spherical lens have each of a focal length -15 cm. The mirror and lens are likely to be [NCERT] (a) both concave (b) both convex (c) mirror is concave and lens is convex (d) mirror is convex and lens is concave Answer: (a) The focal length is taken as negative for both concave mirror and concave lens.
Question 8. Under which of the following conditions, a concave mirror can form an image larger than the actual object? [NCERT Exemplar] (a) When an object is kept at a distance equal to its radius of curvature (b) When an object is kept at a distance less than its focal length (c) When an object is placed between the focus and centre of curvature (d) When an object is kept at a distance greater than its radius of curvature Answer: (c) A concave mirror can form an image enlarged, real and inverted than the actual object, beyond centre of curvature (C) when object is placed between the focus (F) and centre of curvature.
Question 13. Which of the following statement is true? [NCERT Exemplar] (a) A convex lens has 4D power having a focal length 0.25 m (b) A convex lens has 4D power having a focal length -0.25 m (c) A concave lens has 4D power having a focal length 0.25 m (d) A concave lens has 4D power having a focal length -0.25 m Answer: (a) The power P of a lens of focal length f is given by P = 1/f, where f is the focal length in metre and P is the power in dioptre. P= 1/f or f = 1/P = 1/4 = 0.25 m
Question 14. Magnification produced by a rear view mirror fitted in vehicles [NCERT Exemplar] (a) is less than one (b) is more than one (c) is equal to one (d) can be more than or less than one depending upon the position of the object in front of it. Answer: (a) The convex mirror forms virtual, erect and diminished image of the object and rear view mirror also form same type of image. Therefore, magnification (m) produced by a rear view mirror fitted in vehicles is less than one, i.e. m < 1.
Question 15. Rays from the Sun converge at a point 15 cm in front of a concave mirror. Where should an object be placed, so that size of its image is equal to the size of the object? [NCERT Exemplar] (a) 15 cm in front of the mirror (b) 30 cm in front of the mirror (c) between 15 cm and 30 cm in front of the mirror (d) more than 30 cm in front of the mirror Answer: (b) The rays from the Sun, i.e. from infinity, are parallel to principal axis after reflection converge at a point is known as focus. Therefore, focal length if) of concave mirror is 15 cm. And we know that, same size, real and inverted image is formed by concave mirror when object is placed at focus 2 A or centre of curvature, so to form same size of image, object will be placed at 15 x 2 =30 cm.
Question 17. You are given water, mustard oil, glycerine and kerosene. In which of these media, a ray of light incident obliquely at same angle would bend the most? [NCERT Exemplar] (a) Kerosene (b) Water (c) Mustard oil (d) Glycerine Answer: (d) The given material having their refractive index as kerosene is 1.44, water is 1.33, mustard oil is 1.46 and glycerine is 1.74. Thus, glycerine is most optically denser and hence have the largest refractive index. Therefore, ray of light bend most in glycerine.
Question 18. A student placed a light bulb in midway between the two plane mirrors inclined at an angle of 60°. How many images will be observed by him? (a) 4 (b) 6 (c) 5 (d) 8 Answer: (c) Number of images formed by two plane mirrors inclined at an angle 60° when a light bulb is placed in midway between them is N = 360°/60° – 1 = 6 – 1 = 5
Question 19. Where should an object be placed in front of a convex lens to get a real image of the size of the object? [NCERT] (a) At the principal focus of the lens (b) At twice the focal length (c) At infinity (d) Between the optical centre of the lens and its principal focus Answer: (b) To set the real image of the size of the object, it should be placed at twice the focal length of a convex lens.
Question 20. Which of the following lenses would you prefer to use while reading small letters found in dictionary? [NCERT] (a) A convex lens of focal length 50 cm (b) A concave lens of focal length 50 cm (c) A convex lens of focal length 5 cm (d) A concave lens of focal length 5 cm Answer: (c) Convex lens is used as magnifying glass. For better performance its focal length should be small.
LIGHT REFLECTION & REFRACTION Form of energy produces the sensation of vision in eyes. Light (EM waves wave-length 400 nm to 750 nm). The path of light (always travel in straight line) is ray of light
Characteristics of light
Law of Refraction Refraction of light: Bending of light ray while passing from one medium to another medium
Total internal Reflection : Ray totally reflected back to denser medium Phenomena based on TIR
Necessary conditions for TIR (i ) Ray of light must travel from denser to rarer medium (ii) ∠i > ∠c for two media
Critical angle (c) Angle i in denser medium for which angle of refraction in rarer medium is 90° μ = \(\frac{1}{\sin C}\)
Snell’s law μ = \(\frac{\sin i}{\sin r}\) For two media 1 μ 2 = \(\frac{\mu_{2}}{\mu_{1}}=\frac{\sin i}{\sin r}\)
Reflection of light: Turning back of light in the same medium after striking the reflecting surface or mirror
Regular Reflection
Reflection on smooth surface.
Diffuse Reflection Reflection on rough surface.
Laws of Reflection
The incident ray the normal and the reflected ray all lie in the same plane The angle of incidence (i) is always equal to angle of reflection (r) i.e., ∠i = ∠r
Mirror formula \(\frac{1}{f}=\frac{1}{u}+\frac{1}{v}\) When two plane mirrors are held at an angle 9 with their reflecting surfaces facing each other and an object is placed between them, images are formed by successive reflections. . f concave = negative f convex = positive and f plane = ∞
Relation between focal length (f) and radius of curvature, R f = \(\frac{R}{2}\)
Magnification m = \(\frac{\mathrm{v}}{\mathrm{u}}=\frac{\text { height of image }}{\text { height of object }}\) m = \(\frac{f}{f-u}=\frac{f-v}{f}\)
The incident ray, the normal and the refracted ray all lie in the same plane Refractive index, μ = \(\frac{c}{v}=\frac{\text { real depth }}{\text { apparent depth }}\)
Plane Mirror
Is a looking glass, highly polished on one surface.
Concave Mirror Spherical glass polished on the outside. It is also known as a converging mirror.
Image formation by a convex mirror for different positions of the object
Anywhere between Between Pole(P) and infinity (∞) | Between P and F back of the mirror | Small | Virtual and erect |
At infinity | At F | Very small in size | Virtual and erect |
Convex Mirror Spherical glass polished inside. It is also known as diverging mirror.
Image formation by a concave mirror for different positions of the object
At infinity | At the focus F | Highly -diminished, point-sized | Real and inverted |
BeyondC | Between F and C’ | Diminished | Real and inverted |
At C | At C | Same size | Real and inverted |
B/W C and F | Beyond C | Enlarged | Real and inverted |
At F | At infinity | Highly enlarged | Real and inverted |
B/W P and F | Behind the mirror | Enlarged | Virtual and erect |
Atmospheric Refraction
Earth’s atmosphere is thin at the top and dense at the bottom, thus leads to refraction of light, μ = c/v
Refraction Through a Glass Slab x = \(\frac{t \sin (i-r)}{\cos r}\) ∴ x ∝ μ
Power of a lens
P = \(\frac{1}{f(\text { in metre })}\) Unit of power of lens is diopter (D) P convex → Positive P concave → Negative and P plane → Zero
Lens Piece of transparent material with two refracting surfaces, at least one is curved and refractive index should different as that of the surrounding.
Lens formula \(\frac{1}{f}=\frac{1}{v}-\frac{1}{u}\) f convex → negative f concave → positive and f plane → ∞
Concave Lens Cental portion of lens is thinner than marginal. It as also known as diverging lens.
Convex Lens Central portion of lens is thicker than marginal. It is also known us converging lens.
Magnification Ratio of distance of image to the distance of object from the optical centre. Also equal to height of image to the height of object m = \(\frac{\mathrm{I}}{\mathrm{o}}=\frac{\mathrm{v}}{\mathrm{u}}=\frac{\mathrm{h}_{\mathrm{I}}}{\mathrm{h}_{\mathrm{o}}}\)
Nature, position and relative size of the image formed by a concave lens for various position of the object
At infinity | At focus F | Highly-diminished, point-sized | Virtual and erect |
Between infinity and Optical centre O of the lens | Between F and Optical centre O | Diminished | Virtual and erect |
Nature, position and relative size of the image formed by a convex lens for various positions of the object
At infinity | At focus F | Highly -diminished, point-sized | Real and inverted |
Beyond 2F | Between F and 2F | Diminished | Real and inverted |
At 2F | At 2F | Same size | Real and inverted |
Between F and 2F | Beyond 2F | Enlarged | Rea! and inverted |
At Focus F | At infinity | Infinitely large or highly enlarged | Real and inverted |
Between F and Optical centre O | On the same side of the lens as the object | Enlarged | Virtual and erect |
Now that you are provided all the necessary information regarding NCERT Solutions For Class 10 Science Chapter 10 Light Reflection and Refraction and we hope this detailed article on light reflection and refraction class 10 NCERT solutions is helpful. If you have any questions related to this article, kindly ask your questions through the comment section below and we will get back to you as soon as possible.
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NCERT Solutions for Class 10 Science Chapter 10 Light Reflection and Refraction
July 13, 2020 by Veerendra
These Solutions are part of NCERT Solutions for Class 10 Science . Here we have given NCERT Solutions for Class 10 Science Chapter 10 Light Reflection and Refraction. Learn Insta provides you the Free PDF download of NCERT Solutions for Class 10 Science (Physics) Chapter 10 – Light Reflection and Refraction solved by Expert Teachers as per NCERT (CBSE) Book guidelines. All Chapter 10 – Light Reflection and Refraction Exercise Questions with Solutions to help you to revise complete Syllabus and Score More marks.
NCERT Questions
In Text Book Questions
Question 1. Define the principal focus of a concave mirror. Answer: A point on the principal axis where the parallel rays of light after reflecting from a concave mirror meet.
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Question 3. Name a mirror that can give an erect and magnified image of an object. Answer: A concave mirror.
Question 4. Why do we prefer a convex mirror as a rear-view mirror in vehicles ? [CBSE (All India) 2007, 2011, 2012] Answer: This is because a convex mirror forms an erect and diminished (small in size) images of the objects behind the vehicle and hence the field of view behind the vehicle is increased.
Question 5. Find the focal length of a convex mirror whose radius of curvature is 32 cm. Answer: R = +32 cm. Therefore, f = R/2 = +32/2 = +16 cm. Thus, focal length of the convex mirror = +16 cm.
Question 6. A concave mirror produces three times magnified (enlarged) real image of an object placed at 10 cm in front of it. Where is the image located ? Answer: m – -3, But m = -v/u, so v = 3u u = -10 cm v = 3 (-10 cm) =-30 cm Thus, the image is located at a distance of 30 cm to the left side of the concave mirror.
Question 7. A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or away from the normal ? Why ? Answer: The ray of light bends towards the normal because the speed of light decreases when it goes from air (rarer medium) into water (denser medium).
Question 9. You are given kerosene, turpentine and water. In which of these does the light travel faster ? Answer: We know, v = c/n. Refractive index (n) of water is 1.333, whereas refractive index of kerosene is 1.44 and that of turpentine is 1.47. As refractive index of water is least, so speed of light in water is more than in kerosene and turpentine. Hence, light travels faster in water.
Question 11. Define 1 dioptre of power of a lens. Answer: Power = I/f (in m). Power of a lens is 1 dioptre if focal length of the lens is 1 metre or 100 cm.
NCERT Chapter End Exercises
Question 1. Which one of the following materials cannot be tised to make a lens 1 (a) water (b) glass (c) plastic (d) clay. Answer: (d). This is because clay is opaque (i.e. light cannot pass through it).
Question 2. The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object ? (a) between the principal focus and the centre of curvature (b) at the centre of curvature (c) beyond the centre of curvature (d) between the pole of the mirror and its principal focus. Answer: (d).
Question 3. Where should an object be placed in front of a convex lens to get a real image of the size of the object ? (Bihar Board 2012) (a) at the principal focus of the lens (b) at twice the focal length (c) at infinity (d) between the optical centre of the lens and its principal focus. Answer: (b).
Question 4. A spherical mirror and a thin spherical lens have each a focal length of — 15 cm. The mirror and the lens are likely to be (a) both are concave (b) both are convex (c) the mirror is concave and the lens is convex (d) the mirror is convex but the lens is concave. Answer: (a).
Question 5. No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be (a) plane only (b) concave only (c) convex only (d) either plane or convex. Answer: (d).
Question 6. Which of the following lenses would you prefer to use while reading small letters found in a dictionary ? (a) a convex lens of focal length 50 cm (b) a concave lens of focal length 50 cm (c) a convex lens of focal length 5 cm (d) a concave lens of focal length 5 cm. Answer: (c). Magnifying power of a reading glass (Convex lens) = 1/f.
Question 7. We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. What should be the range of distance of the object from the mirror ? What is the nature of the image ? Is the image larger or smaller than the object ? Draw a ray diagram to show the image formation in this case. Answer: A concave mirror produces an erect image if the object is placed between the pole and the focus of the concave mirror. Thus, object may be placed at any position whose distance is less than 15 cm from the concave mirror. The image is virtual and erect. The image is larger than the object. For a ray diagram, see figure 24.
Question 8. Name the type of mirror used in the following situations : (a) head lights of a car (b) side rear view mirror of a vehicle (c) solar furnace. Support your answer with reason. (CBSE 2012, 2013) Answer: (a) Concave mirror. When a bulb is placed at the focus of a concave mirror, then the beam of light from the bulb after reflection from the concave mirror goes as a parallel beam which lights up the front road. (b) Convex mirror. Image formed by a convex mirror is erect and small in size. The field of view behind the vehicle is large. (c) Concave mirror. Concave mirror focuses rays of light coming from the sun at its focus. So, the temperature at the focus is raised.
Practical Skills Based Questions (2 Marks)
Get 100 percent accurate NCERT Solutions for Class 10 Science Chapter 10 (Light Reflection and Refraction) explained by expert Science teachers. We provide step by step solutions for the questions given in Class 10 Science textbook as per CBSE Board guidelines from the latest NCERT book for Class 10 Science. The topics and sub-topics in Chapter 10 Light Reflection and Refraction
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Ncert solutions class 10 science chapter 10 – cbse free pdf download.
* According to the CBSE Syllabus 2023-24, this chapter has been renumbered as Chapter 9.
NCERT Solutions for Class 10 Science Chapter 10 Light Reflection and Refraction is structured in a way to present a comprehensible coverage of scientific topics related to our daily life. Basic science has been laid out to students with no sharp divisions in disciplines such as Physics, Chemistry and Biology. NCERT is accepted and recommended throughout schools in the nation. Following are a few reasons to rely on NCERT Solutions :
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Questions Page: 168
1. Define the principal focus of a concave mirror.
Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror. This point is called the principal focus of the concave mirror.
2. The radius of curvature of a spherical mirror is 20 cm. What is its focal length?
Radius of curvature (R) = 20 cm
Radius of curvature of the spherical mirror = 2 × Focal length (f)
f= R/2 = 20 / 2 = 10
Therefore, the focal length of the spherical mirror is 10 cm.
3. Name the mirror that can give an erect and enlarged image of an object.
The mirror that can give an erect and enlarged image of an object is a Concave Mirror.
4. Why do we prefer a convex mirror as a rear-view mirror in vehicles?
A convex mirror is preferred as a rear-view mirror in cars and vehicles as it gives a wider field of view, which helps the driver see most of the traffic behind him. Convex mirrors always form an erect, virtual, and diminished image of the objects placed in front of it.
Page No: 171
1. Find the focal length of a convex mirror whose radius of curvature is 32 cm.
Radius of curvature (R) = 32 cm
Radius of curvature = 2 × Focal length (f)
f = R/2 = 32/2 = 16
Therefore, the focal length of the given convex mirror is 16 cm.
2. A concave mirror produces three times magnified (enlarged) real image of an object placed at 10 cm in front of it. Where is the image located?
Magnification produced by a spherical mirror:
Object distance (u) = – 10 cm
v = 3 × (- 10) = – 30 cm
Therefore, the negative sign indicates that an inverted image is formed in front of the given concave mirror at a distance of 30 cm.
Page No: 176
1. A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or away from the normal? Why?
The light ray bends towards the normal. When a light ray enters from an optically rarer medium (which has a low refractive index) to an optically denser medium (which has a high refractive index), its speed slows down and bends towards the normal. As water is optically denser than air, a ray of light entering from air into water will bend towards the normal.
2. Light enters from air to glass, having a refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 x 10 8 ms -1 .
Refractive index of a medium (nm) = Speed of light in vacuum/Speed of light in the medium
Speed of light in vacuum (c) = 3 × 10 8 m/s
Refractive index of glass (ng) = 1.50
Speed of light in the glass (v) = Speed of light in vacuum/ Refractive index of glass
=3 × 10 8 /1.50 = 2x 10 8 ms -1 .
3. Find out, from the table, the medium having the highest optical density. Also, find the medium with the lowest optical density.
|
| ||
1.0003 | Canada Balsam | 1.53 | |
1.31 | – | – | |
1.33 | Rock salt | 1.54 | |
1.36 | – | – | |
1.44 | Carbon disulphide | 1.63 | |
| 1.46 | Dense flint glass | 1.65 |
1.47 | Ruby | 1.71 | |
1.50 | Sapphire | 1.77 | |
| 1.52 | Diamond | 2.42 |
Lowest optical density = Air
Highest optical density = Diamond
The optical density of a medium is directly related to its refractive index. A medium with the highest refractive index will have the highest optical density and vice-versa.
It can be observed from the table that air and diamond, respectively have the lowest and highest refractive index. Hence, air has the lowest optical density and diamond has the highest optical density.
4. You are given kerosene, turpentine and water. In which of these does the light travel fastest? Use the information given in the table.
Light travels faster in water as compared to kerosene & turpentine, as the refractive index of water is lower than that of kerosene and turpentine. The speed of light is inversely proportional to the refractive index.
5. The refractive index of diamond is 2.42. What is the meaning of this statement?
A diamond has a refractive index of 2.42, which means that the speed of light in a diamond will reduce by a factor of 2.42 as compared to its speed in the air.
In other words, the speed of light in a diamond is 1/2.42 times the speed of light in a vacuum.
Page No: 184
1. Define 1 dioptre of power of a lens.
Dioptre is the SI unit of power of lens is denoted by the letter D. 1 dioptre can be defined as the power of a lens of focal length 1 metre.
2. A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.
The position of the image should be at 2F since the image is real and the same size.
It is given that the image of the needle is formed at a distance of 50 cm from the convex lens. Therefore, the needle is placed in front of the lens at a distance of 50 cm.
Object distance (u) = – 50 cm
Image distance, (v) = 50 cm
Focal length = f
According to the lens formula,
3. Find the power of a concave lens of focal length 2 m.
The focal length of the concave lens (f) = 2 m
Power of lens (P) = 1/f = 1/ (-2) = -0.5D
Page No: 185
1. Which one of the following materials cannot be used to make a lens?
(c) Plastic
Answer –
(d) Clay cannot be used to make a lens because if the lens is made up of clay, the light rays cannot pass through it
2. The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object?
(a) Between the principal focus and the centre of curvature
(b) At the centre of curvature
(c) Beyond the centre of curvature
(d) Between the pole of the mirror and its principal focus.
(d) The position of the object should be between the pole of the mirror and its principal focus.
3. Where should an object be placed in front of a convex lens to get a real image of the size of the object?
(a) At the principal focus of the lens
(b) At twice the focal length
(c) At infinity
(d) Between the optical centre of the lens and its principal focus.
(b) The object should be placed at twice the focal length
4. A spherical mirror and a thin spherical lens have a focal length of -15 cm. The mirror and the lens are likely to be
(a) both concave
(b) both convex
(c) the mirror is concave, and the lens is convex
(d) the mirror is convex, but the lens is concave
(a) Both are likely to be concave.
Page No: 186
5. No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be
(b) concave
(d) either plane or convex
(d) The mirrors are likely to be either plane or convex
6. Which of the following lenses would you prefer to use while reading small letters found in a dictionary?
(a) A convex lens of focal length 50 cm
(b) A concave lens of focal length 50 cm
(c) A convex lens of focal length 5 cm
(d) A concave lens of focal length 5 cm
(c) A convex lens of focal length 5 cm can be used while reading small letters found in a dictionary
7. We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. What should be the range of distance of the object from the mirror? What is the nature of the image? Is the image larger or smaller than the object? Draw a ray diagram to show the image formation in this case.
Range of the distance of the object = 0 to 15 cm from the pole of the mirror.
Nature of the image = virtual, erect, and larger than the object.
8. Name the type of mirror used in the following situations.
(a) Headlights of a car
(b) Side/rear-view mirror of a vehicle
(c) Solar furnace
Support your answer with a reason.
(a) Concave Mirror: Concave mirrors can produce a powerful parallel beam of light when the light source is placed at their principal focus.
(b) Convex Mirror: Because of its largest field of view.
(c) Concave Mirror: Because it concentrates the parallel rays of the sun at a principal focus.
9. One-half of a convex lens is covered with black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.
Yes, it will produce a complete image of the object, as shown in the figure. This can be verified experimentally by observing the image of a distant object, like a tree on a screen, when the lower half of the lens is covered with black paper. However, the intensity or brightness of the image will reduce.
10. An object 5 cm in length is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray diagram and find the position, size and nature of the image formed.
Height of the object, h 0 = 5 cm
Distance of the object from converging lens, u = -25 cm
Focal length of a converging lens, f = 10 cm
Using the lens formula,
Thus, the image is inverted and formed at a distance of 16.7 cm behind the lens and measures 3.3 cm. The ray diagram is shown below.
11. A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens? Draw the ray diagram.
Focal length of concave lens (OF 1 ), f = – 15 cm
Image distance, v= – 10 cm
The negative value of u indicates that the object is placed 30 cm in front of the lens. This is shown in the following ray diagram.
12. An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of the image.
Focal length of convex mirror (f) = +15 cm
According to the mirror formula,
The image is located at a distance of 6 cm from the mirror on the other side of the mirror.
The positive and a value of less than 1 magnification indicates that the image formed is virtual, erect, and diminished.
13. The magnification produced by a plane mirror is +1. What does this mean?
The positive sign means an image formed by a plane mirror is virtual and erect. Since the magnification is 1, it means that the size of the image is equal to the size of the object.
14. An object 5 cm is placed at a distance of 20 cm in front of a convex mirror of radius of curvature 30 cm. Find the position, nature and size of the image.
Object distance (u) = – 20 cm
Object height (h) = 5 cm
Radius of curvature (R) = 30 cm
Radius of curvature = 2 × Focal length
The positive value of image height indicates that the image formed is erect.
Hence, the image formed is erect, virtual, and smaller in size.
15. An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed so that a sharply focused image can be obtained? Find the size and nature of the image.
Object distance (u) = – 27 cm
Object height (h) = 7 cm
Focal length (f) = – 18 cm
The negative value of image height indicates that the image formed is inverted.
16. Find the focal length of a lens of power -2.0 D. What type of lens is this?
Power of lens (P) = 1/f
f = -1/2 = -0.5 m
A concave lens has a negative focal length. Therefore, it is a concave lens.
17. A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?
f = 1/1.5 = 10/15 = 0.66 m
A convex lens has a positive focal length. Therefore, it is a convex lens or a converging lens.
Chapter 10 Light Reflection and Refraction are one of the important chapters in Class 10 Science, and the expected marks weightage of the chapter, according to the latest marking scheme is 7 marks. In Chapter 10 of Class 10 Science, students will get well-versed in light phenomena such as refraction and reflection. One will learn about spherical mirrors, image formation and to draw ray diagrams.
Topics covered in this chapter:
Have you ever wondered what makes things visible to us? The answer to the question is light. During the day, it is sunlight that helps us see objects. When light falls on an object, it reflects. This reflected ray, when received by our eyes, helps us see things. Numerous wonderful phenomena are associated with light, such as the formation of the rainbow, of stars, and many more. In Chapter 10 Light Reflection and Refraction of Class 10 Science, let us study the phenomena of refraction and reflection using straight-line propagation of light. We shall also try to understand the reflection of light by spherical mirrors in this chapter using the NCERT Solutions from BYJU’S.
Is the byju’s ncert solutions for class 10 science chapter 10 available in pdf format, what are the uses of referring to byju’s ncert solutions for class 10 science chapter 10, what are the topics covered in the ncert solutions for class 10 science light reflection and refraction, and how many questions are present under each of them, leave a comment cancel reply.
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10 questions mcq test - case based questions test: light- reflection & refraction - 1, following figure illustrates the ray diagram for the formation of images by a concave mirror. the position of the object is beyond the centre of curvature of the concave mirror. on the basis of given diagram, answer the questions. if the focal length of the concave mirror is 10 cm, the image formed will be at a distance ___________..
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Read the following passage and answer the questions.
A student wants to project the image of a candle flame on the walls of the school laboratory by using a mirror.
At what distance, in terms of focal length ‘f’ of the mirror, should he place the candle flame to get the magnified image on the wall ?
(ii) In order to form a diminished image on the wall, the candle flame should be placed at a distance greater than 2F from the lens.
If the image formed by this mirror is inverted and real, the magnification will be:
A student wants to project the image of a candle flame on a screen 30 cm in front of a mirror by keeping the flame at a distance of 15 cm from its pole.
Suggest the type of mirror he should use:
When object distance is less than focal length the image is _______ and when object distance is more than focal length the image is ______.
The image formed in the above case is:
real , inverted and magnified
real, erect and magnified
virtual, inverted and magnified.
real, erect and diminished
A real image occurs where rays converge, whereas a virtual image occurs where rays only appear to diverge. Real images can be produced by concave mirrors and converging lenses, only if the object is placed further away from the mirror/lens than the focal point, and this real image is inverted.
Read the passage and note the following observations. Answer the questions.
A student focussed the image of a candle flame on a white screen by placing the flame at various distances from a convex lens. He noted his observations as:
Which set of observations is incorrect and why?
(b) The observation (v) is incorrect. For this observation u = 15 = /, i.eThe object is at the focus and the image must be formed at infinity and not 70 cm.
(c) Since m = v/u , the size of the image will be equal to the size of the object, if v = u i.e., for the observation (iii).
What is the change in image observed as the object is moved from infinity towards the concave lens?
Case based questions test: light- reflection & refraction - 1 mcqs with answers, online tests for case based questions test: light- reflection & refraction - 1.
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Here we are providing HOTS Questions for CBSE Class 10 Science . In this article, we are providing HOTS Questions for CBSE Class 10 Science Chapter 10 Light Reflection and Refraction . Students are suggested to go through all chapter HOTS Questions for better understanding and exam preparation.
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HOTS stands for “Higher Order Thinking Skills”. HOTS questions are designed to test a student’s ability to think beyond just rote memorization and recall of information. These questions require the student to apply, analyze, synthesize, and evaluate information in order to arrive at a solution or answer.
Requires higher-level thinking: HOTS questions require students to apply, analyze, synthesize, and evaluate information to arrive at a solution or answer. This requires a higher level of thinking and understanding, beyond just rote memorization and recall of information.
Requires interpretation and analysis of data: HOTS questions often involve analyzing and interpreting data, making connections between different concepts, and formulating hypotheses.
Complex: HOTS questions are often complex and require the student to think deeply about the problem at hand. They may involve multiple steps or require the student to use different types of information or knowledge to arrive at a solution or answer.
Real-world application: HOTS questions are designed to assess a student’s ability to apply their knowledge in real-world situations. They may involve scenarios that students are likely to encounter in their future academic or professional careers.
Emphasizes critical thinking and problem-solving skills: HOTS questions require the student to use critical thinking and problem-solving skills to arrive at a solution or answer. These skills are important for success in higher education and in the workplace.
Overall, HOTS questions are designed to test a student’s ability to think beyond just rote memorization and recall of information, and to apply their knowledge in real-world situations. By practicing these types of questions, students can develop their higher-order thinking skills and be better prepared for success in higher education and in the workplace.
HOTS (Higher Order Thinking Skills) questions in CBSE Class 10 Science are important because they require students to apply their knowledge and understanding of concepts in a more complex and analytical way. HOTS questions are designed to evaluate students’ ability to analyze, synthesize, and evaluate information, rather than simply recall information.
In the CBSE Class 10 Science exam, HOTS questions can appear in both the objective and subjective sections of the paper. These questions typically require students to think critically and apply their knowledge in real-world situations. They may involve analyzing and interpreting data, making connections between different concepts, and formulating hypotheses.
By practicing HOTS questions, students can develop their critical thinking and problem-solving skills, which are essential for success in higher education and in the workplace. HOTS questions also help students to better understand the subject matter and to develop a deeper appreciation for the scientific process.
Therefore, it is important for CBSE Class 10 Science students to focus on HOTS questions and practice them regularly in order to excel in their exams and develop valuable skills for their future.
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Here, we have provided case based/passage based questions for Class 10 Science Chapter 10 Light Reflection and Refraction. Question 1: Read the following and answer any four questions from (i) to (v). The spherical mirror forms different types of images when the object is placed at different locations.
Explanation: In a convex spherical mirror, reflection of light takes place at a bulging-out surface. Question 2: Read the following and answer the questions given below: A lens is a piece of any transparent material bounded by two curved surfaces. There are two types of lenses convex lens and concave lens.
Contents. Case Study Questions Class 10 Science Chapter 10 Light Reflection and Refraction Case study:1 Case study: 2 Case study:3. At Case Study Questions there will given a Paragraph. In where some Important Questions will made on that respective Case Based Study. There will various types of marks will given 1 marks, 2 marks, 3 marks, 4 marks.
CBSE 10th Standard Science Subject Light Reflection and Refraction Case Study Questions With Solution 2021 Answer Keys. (i) (b): The focal length of a concave mirror is the distance between its pole and principal focus. (ii) (b) (iii) (b): Given that, f = 15 cm. Radius of curvature of a spherical mirror is given as. R= 2F.
Here, we have provided case-based/passage-based questions for Class 10 Science Chapter 10 Light Reflection and Refraction. Case Study/Passage-Based Questions. Question 1: The spherical mirror forms different types of images when the object is placed at different locations. When the image is formed on the screen, the image is real and when the ...
rarer medium whereas in which the speed of light is less is optically denser medium. Whenever light goes from one medium to another. the frequency Of light does not change however, speed and wavelength change. It concluded that change in speed of light is the basic cause of refraction. (i) When light travels from air to glass, the ray Of light ...
Students who are studying in CBSE class 10 board, need to get the knowledge about the Light Reflection and Refraction Case Study Based Questions. Case based questions are generally based on the seen passages from the chapter Light Reflection and Refraction. Through solving the case based questions, students can understand each and every concept.
Case Study Questions Chapter 1 Light Reflection and Refraction. Case/Passage - 1. A 5.0 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 30 cm. Question: What is the power of the used lens? (a) + 5 D. (b) - 5 D. (c) + 0.5 D.
Here, we have provided case-based/passage-based questions for Class 10 Science Chapter 10 Light Reflection and Refraction. Case Study/Passage-Based Questions. Question 1: The spherical mirror forms different types of images when the object is placed at different locations. When the image is formed on the screen, the image is real and when the ...
Important Questions for CBSE Class 10 Science Chapter 10 Light Reflection and Refraction MULTIPLE CHOICE QUESTIONS. Q.1. Rays from the sun converge at a point 15 cm in front of a concave mirror.
Question 3. State the two laws of reflection of light. (Delhi 2011) Answer: Laws of reflection of light states that. (i) The angle of incidence is equal to the angle of reflection. (ii) The incident ray, the reflected ray and the normal to the mirror at the point of incidence all lie in the same plane. Question 4.
2 2014. Q3.7. Draw a ray diagram to show the path of the reflected ray corresponding to an incident ray of light parallel to the principal axis of a concave mirror. Mark on it the angle of incidence and the angle of reflection. 2 2014. Q3.8. An object is placed between infinity and the pole of a convex mirror.
In this page we have provided NCERT Solutions for Class 10 Science Chapter 10 Light Reflection and Refraction through which you can complete your homework on time and increase concentration as well. These Chapter 10 NCERT questions and answers of Class 10 Science will help you in analyzing the problems and answering it with precision and the right concepts.
Document Description: Case Based Type Practice Questions: Light- Reflection & Refraction for Class 10 2024 is part of Physics for Class 10 preparation. The notes and questions for Case Based Type Practice Questions: Light- Reflection & Refraction have been prepared according to the Class 10 exam syllabus. Information about Case Based Type Practice Questions: Light- Reflection & Refraction ...
Answer: Two basic laws of refraction of light are: (i) The incident ray, the refracted ray and the normal to the separating surface at the point of incidence, all lie in the same plane. (ii) The ratio of sine of the angle of incidence to the sine of angle of refraction (r) is a constant. It is known as Snell's law.
Students can find the Important Questions for Class 10 Science Chapter 10, Light Reflection And Refraction, on this page. From this chapter, both types of questions are asked, i.e., theory as well as numerical. So, students need to practice both types of questions. Here, in the important questions, we have provided a mix of theory and numerical ...
The Important Questions for Class 10 Science Light Reflection and Refraction have simple explanations. All the concepts in this chapter will be exceptionally simplified and utilized to answer these important questions. Hence, the students will get another way to learn how to use the textbook concepts to solve challenging questions in the exams.
Spherical Mirrors. Refraction Of Light. Free download NCERT Solutions for Class 10 Science Chapter 10 Light Reflection and Refraction PDF in Hindi Medium as well as in English Medium for CBSE, Uttarakhand, Bihar, MP Board, Gujarat Board, and UP Board students, who are using NCERT Books based on updated CBSE Syllabus for the session 2019-20.
Answer Key 10.6. 5 Passages. 25 questions. Download case study question pdfs for CBSE Class 10th Maths, CBSE Class 10th English, CBSE Class 10th Sciece, CBSE Class 10th SST. As the CBSE 10th Term-1 Board Exams are approaching fast, you can use these worksheets for FREE for practice by students for the new case study formats for CBSE introduced ...
Answer: We know, v = c/n. Refractive index (n) of water is 1.333, whereas refractive index of kerosene is 1.44 and that of turpentine is 1.47. As refractive index of water is least, so speed of light in water is more than in kerosene and turpentine. Hence, light travels faster in water. Question 10.
NCERT Solutions Class 10 Science Chapter 10 - CBSE Free PDF Download *According to the CBSE Syllabus 2023-24, this chapter has been renumbered as Chapter 9. NCERT Solutions for Class 10 Science Chapter 10 Light Reflection and Refraction is structured in a way to present a comprehensible coverage of scientific topics related to our daily life. Basic science has been laid out to students with ...
Solutions of Case Based Questions Test: Light- Reflection & Refraction - 1 questions in English are available as part of our course for Class 10 & Case Based Questions Test: Light- Reflection & Refraction - 1 solutions in Hindi for Class 10 course. Download more important topics, notes, lectures and mock test series for Class 10 Exam by signing up for free.
In this article, we are providing HOTS Questions for CBSE Class 10 Science Chapter 10 Light Reflection and Refraction. Students are suggested to go through all chapter HOTS Questions for better understanding and exam preparation. ... Case Study Questions for Class 9 Science Chapter 1 Matter in Our Surroundings; An Imperial Capital ...