NCERT Exemplar Class 10 Science Chapter 10 Light Reflection And Refraction

Chapter 10 Light Reflection And Refraction NCERT Exemplar for class 10 Science

NCERT Exemplar Solutions for Class 10 Science Chapter 10 Light Reflection and Refraction will boost your confidence in attempting the board exam as this topic is considered as one of the easiest beat if the student has a good command over commands and formulas. In Chapter 10, students will understand the phenomena of reflection and refraction of light, and at the same time, they will learn about the basic concepts related to some optical phenomena occurring in nature. Students in this chapter will able to explore a lot more about light,its phases,diversions and much more.

Simply Acad is providing you with the correct source of content that covers all potential questions that can be raised on the basis of the topic in pdf format for free. These exemplars will facilitate easy learning, and students will be able to get clarity on all the concepts and topics given in this chapter. Besides, these Exemplar Solutions that are given here act as a very useful reference tool which will help them get familiar with all the important chapter topics, practice questions, complete revisions, and ultimately, be well prepared to write the final exams.

Students can take a quick look at Class 10 Science Chapter 10 NCERT Exemplar by downloading the solutions PDF by scrolling down below!!

1. Which of the following can make a parallel beam of light when light from a point source is incident on it?

(a) Concave mirror as well as convex lens

(b) Convex mirror as well as a concave lens

(c) Two plane mirrors placed at 90° to each other

(d) Concave mirror as well as a concave lens

Soln:

The answer is (a) Concave mirror as well as convex lens

Explanation:

Emergent beams are parallel, and the image is produced at infinity when light rays from a point source are incident on a concave mirror and convex lens.

2. A 10 mm long awl pin is placed vertically in front of a concave mirror. A 5 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is

(a) – 30 cm

(b) – 20 cm

(c) – 40 cm

(d) – 60 cm

Soln:

The answer is (b) – 20 cm

Explanation:

Here, size of object = O = + 10.0 mm = + 1.0 cm (as, 1 cm = 10 mm)

Size of Image size = I = 5.0 mm = 0.5 cm

Image distance, v = − 30 cm (as the image is real)

Let, object distance = u

Focal length, f =?

Magnification m= I(size of image)/O(size of image)

Magnification is given by m= -v/u

i/o=-V/u

0.5/1=-30/u

U = -60cm

Focal length is given by 1/f =1/v + 1/u

1/f=1/-30 + 1/60

= -2-1/60

=-3/60

F= -20cm

3. Under which of the following conditions a concave mirror can form an image larger than the actual object?

(a) When the 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

Soln:

The answer is (c) When an object is placed between the focus and centre of curvature

Explanation:

When an object is placed between F and C, an enlarged image is formed beyond C.

4. Figure 10.1 shows a ray of light as it travels from medium A to medium B. Refractive index of the

medium B relative to medium A is

(a) √3 / √2

(b) 2 / 3

(c) 1/ 2

(d) 2

Soln:

The answer is (a) 3 / 2

Refractive Index of B with respect to A

=sin i/sin r

=sin60/sin45

= ( √3 /2) /(1/ √2)

= √3 / √2

5. A light ray enters from medium A to medium B, as shown in Figure 10.2. The refractive

index of medium B relative to A will be

(a) greater than unity

(b) less than unity

(c) equal to unity

(d) zero

Soln:

The answer is (a) greater than unity

6. Beams of light are incident through holes A and B and emerge out of the box through holes C and D, respectively, as shown in the Figure10.3. Which of the following could be inside the box?

(a) A rectangular glass slab

(b) A convex lens

(c) A concave lens

(d) A prism

Soln:

The answer is (a) A rectangular glass slab

Explanation:

When incident rays fall perpendicularly on the point of incidence. A rectangular glass slab would refract and then re-refract it.

7. A beam of light is incident through the holes on side A and emerges out of the holes on the other face of the box, as shown in Figure 10.4. Which of the following could be inside the box?

(a) Concave lens

(b) Rectangular glass slab

(c) Prism

(d) Convex lens

Soln:

The answer is (d) Convex lens

Explanation:

Convex lenses are converging lenses. They have the ability to converge a parallel beam of light into a point.

8. Which of the following statements is true?

(a) A convex lens has 4 dioptre power having a focal length 0.25 m

(b) A convex lens has –4 dioptre power having a focal length 0.25 m

(c) A concave lens has 4 dioptre power having a focal length 0.25 m

(d) A concave lens has –4 dioptre power having a focal length 0.25 m

Soln:

The answer is (a) A convex lens has 4 dioptre power having a focal length 0.25 m

Explanation:

A positive value for focal length indicates a convex lens.

9. Magnification produced by a rearview mirror fitted in vehicles

(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

Soln:

The answer is (a) is less than one

Explanation:

A Convex mirror is used in the rearview mirror. The convex mirror always gives a smaller image. Hence, the magnification produced by the rear view mirror is always less than 1.

10. Rays from 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?

(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

Soln:

The answer is (d) more than 30 cm in front of the mirror

Explanation:

Here f= 15,

The radius of curvature is double the focal length

hence c=30

When an object is placed on c, its image is of the same size, inverted and is formed on c.

11. A full-length image of a distant tall building can definitely be seen by using

(a) a concave mirror

(b) a convex mirror

(c) a plane mirror

(d) both concave as well as plane mirror

Soln:

The answer is (b) a convex mirror

Explanation:

The field of a convex mirror is more than any type of mirror. Hence the full-length size of the building can be seen by using a convex mirror.

12. In torches, searchlights and headlights of vehicles, the bulb is placed

(a) between the pole and the focus of the reflector

(b) very near to the focus of the reflector

(c) between the focus and centre of curvature of the reflector

(d) at the centre of curvature of the reflector

Soln:

The answer is (b) very near to the focus of the reflector

Explanation:

Headlight reflectors and searchlights are in the shape of a concave mirror. When the source of light is placed at the focus, reflected light appears like a beam.

13. The laws of reflection hold good for

(a) plane mirror only

(b) concave mirror only

(c) convex mirror only

(d) all mirrors, irrespective of their shape

Soln:

The answer is (d) all mirrors, irrespective of their shape

14. The path of a ray of light coming from air passing through a rectangular glass slab traced by four students are shown as A, B, C and D in Figure 10.5. Which one of them is correct?

(a) A

(b) B

(c) C

(d) D

Soln: The answer is b) B

Explanation:

Light bends towards normal when it passes from air to glass. Light bends away from normal when it passes from glass to air. This is appropriately shown in figure b).

15. You are given water, mustard oil, glycerine and kerosene. In which of these media a ray of light incident obliquely at the same angle would bend the most?

(a) Kerosene

(b) Water

(c) Mustard oil

(d) Glycerine

Soln:

The answer is (d) Glycerine

Explanation:

Refractive indices

Water-1.33

Kerosene-1.44

Mustard oil-1.46

Glycerine-1.47

Hence Glycerine is optically dense hence ray of light bends more with glycerine.

16. Which of the following ray diagrams is correct for the ray of light incident on a concave mirror as shown in Figure 10.6?

(a) Fig. A

(b) Fig. B

(c) Fig. C

(d) Fig. D

Soln:

The answer is (d) Fig. D

Explanation:

In the case of the concave mirror, an incident ray is parallel to the principal axis and passes through F after reflection.

17. Which of the following ray diagrams is correct for the ray of light incident on a lens shown in Fig. 10.7?

(a) Fig. A.

(b) Fig. B.

(c) Fig. C.

(d) Fig. D.

Soln:

The answer is (a) Fig. A.

Explanation:

In a convex lens, the incident ray passing through F goes parallel to the principal axis after refraction.

18. A child is standing in front of a magic mirror. She finds the image of her head bigger, the middle portion of her body of the same size and that of the legs smaller. The following is the order of combinations for the magic mirror from the top.

(a) Plane, convex and concave

(b) Convex, concave and plane

(c) Concave, plane and convex

(d) Convex, plane and concave

Soln:

The answer is (c) Concave, plane and convex

Explanation:

When the object is between F and P of the concave mirror enlarged image is formed behind the mirror. Hence child can see her head bigger in a concave mirror. She can see her body size of the same size because the plane mirror gives an image of the original size. Convex mirror gives diminished images, and the baby’s legs appear smaller.

19. In which of the following, the image of an object placed at infinity will be highly diminished and point sized?

(a) Concave mirror only

(b) Convex mirror only

(c) Convex lens only

(d) Concave mirror, convex mirror, concave lens and convex lens

Soln:

The answer is (d) Concave mirror, convex mirror, concave lens and convex lens

20. Identify the device used as a spherical mirror or lens in the following cases, when the image formed is virtual and erect in each case.

(a) Object is placed between the device and its focus, and an image formed is enlarged and behind it.

(b) Object is placed between the focus and device, and an image formed is enlarged and on the same side as that of the object.

(c) Object is placed between infinity and device, an image formed is diminished and between focus and optical centre on the same side as that of the object.

(d) Object is placed between infinity and device, image formed is diminished and between pole and focus, behind it.

Soln:

(a) Concave mirror