CHAPTER
RAY OPTICS AND OPTICAL
9 INSTRUMENTS
Exercise 1: NCERT Based Topic-wise MCQs
9.1 INTRODUCTION
1. Rectilinear propagation of light means NCERT Page-309 / N-221
(a) Light travels in straight lines
(b) Light travels in curved path
(c) Light travels in zig-zag path
(d) Light travels as a wave
9.2 REFLECTION OF LIGHT BY SPHERICAL MIRRORS
2. An object is placed 40cm from a concave mirror of focal.length 20cm. The image formed is
(a) real, inverted and same in size NCERT Page-312 / N-225
(b) real, inverted and smaller
(c) virtual, erect and larger
(d) virtual, erect and smaller
3. In image formation from spherical mirrors, only paraxial rays are considered because they
(a) are easy to handle geometrically NCERT Page-311 / N-222
(b) contain most of the intensity of the incident light
(c) form nearly a point image of a point source
(d) show minimum dispersion effect
4. For reflection through spherical surfaces, the normal at the point of incidence is NCERT Page-310 / N-222
(a) perpendicular to the principle axis and passes through the centre of curvature.
(b) perpendicular to the focal plane and passes through the pole.
(c) perpendicular to the tangent plane at pole and passes through the focus.
(d) perpendicular to the tangent plane at the point of incidence and passes through the centre of curvature.
5. Figure shows two rays 𝐴 and 𝐵 being reflected by a mirror and going as A′ and B ′ . The mirror
NCERT Page-312 / N-222
(a) is plane
(b) is convex
, (c) is concave
(d) may be any spherical mirror
6. Which of the following is incorrect statement? NCERT Page-314 / N-226
(a) the magnification produced by a convex mirror is always less than one
(b) a virtual, erect, same-sized image can be obtained using a plane mirror
(c) a virtual, erect, magnifield image can be formed using a concave mirror
(d) a real, inverted, same-sized image can be formed using a convex mirror
7. A rod of length 10cm lies along the principal axis of a concave mirror of focal length 10cm in such a way that its
end closer to the pole is 2Ωm away from the mirror. The length of the image is NCERT Page-314 / N-225
(a) 10cm
(b) 15cm
(c) 2.5cm
(d) 5cm
8. A car is fitted with a convexside-view mirror of focal length 20cm. A second car 2.8m behind the first car is
overtaking the first car at a relative speed of 15m/s. The speed of the image of the second car as seen in the mirror
of the first one is: NCERT Page-314 / N-225
1
(a) 15 m/s
(b) 10m/s
(c) 15m/s
1
(d) m/s
10
9. An object is moving with speed 𝑣0 towards a spherical mirror with radius of curvature 𝑅, along the central axis of the
mirror. The speed of the image respect to the mirror is ( 𝑈 is the distance of the object from mirror at any given time
𝑡) NCERT Page-314 / N-225
𝑅
(a) + ( ) 𝑣02
𝑈−2𝑅
𝑅 2
(b) − (𝑅−2𝑈) 𝑣0
𝑅 2
(c) − ( ) 𝑣0
2𝑈−2𝑅
𝑅
(d) + ( ) 𝑣02
2𝑈−2
10. A concave mirror is used for face viewing has focal length of 0.6m. At whay distance you should hold the mirror from
your face to get an upright image with a magnification of 4 ? NCERT Page-314 / N-226
(a) 0.20m
(b) 0.25m
(c) 0.40m
(d) 0.45m
11. A cube of side 2m is placed in front of a concave mirror of focal length 1m with its face 𝑃 at a distance of 3m and
face 𝑄 at a distance of 5m from the mirror. The distance between the image of face 𝑃 and 𝑄 is
(a) 1m NCERT Page-313 / N-225
(b) 0.5m
(c) 0.5m
(d) 0.25m
,12. A short linear object of length ℓ lies along the axis of a concave mirror of focal length 𝑓 at a distance 𝑢 from the pole
of the mirror. The size of the image is approximately equal to, NCERT Page-314 / N-225,226
𝑢−𝑓 1/2
(a) ℓ ( )
𝑓
𝑢−𝑓 2
(b) ℓ ( 𝑓 )
𝑓 1/2
(c) ℓ (𝑢−𝑓)
𝑓 2
(d) ℓ (𝑢−𝑓)
13. An object kept on the principle axis is moving in the same directions as that of mirror as shown in figure. Speed of
object and mirror is 10m/s and 40/12m/s. Radius of the curvature of the mirror is 20cm. What should be the
distance of object from the mirror at this instant so that the image is statonary? NCERT Page-314/ N-225
(a) 25cm
(b) 45cm
(c) 37.5cm
(d) 15cm
14. You are asked to design a shaving mirror assuming that a person keeps it 10cm from his face and views the
magnified image of the face at the closest comfortable distance of 25 cm. The radius of curvature of the mirror
would then be':
(a) 60cm
(b) −24cm
(c) −60cm
(d) 24cm
15. In figure find the total magnification after two successive reflections first on 𝑀1 and then on 𝑀2 .
if NCERT Page-314./ N-226
(a) +1
(b) -2
(c) +2
(d) -1
9.3 REFRACTION
16. As shown in the figure, after passing through the medium 1 . The speed of light 𝑣2 in medium 2 will be :
, (Given c = 3 × 108 ms−1 ) NCERT Page-317 /N − 228
(a) 1.0 × 108 ms −1
(b) 0.5 × 108 ms−1
(c) 1.5 × 108 mg −1
(d) 3.0 × 108 ms−1
17. Light travels through a glass plate of thickness 𝑡 and refractive index 𝜇. If 𝑐 is the speed of light in vacuum, the time
taken by light to travel this thickness of glass is NCERT Page-317 / N-229
(a). 𝜇tc
𝑡𝑐
(b) 𝜇
𝑡
(c) 𝜇𝑐
𝜇𝑡
(d)
𝑐
18. One face of a rectangular glass plate 6cm thick is silvered. An object held 8cm in front of the first face, forms an
image 12cm behind the silvered face. The refractive index of the glass is NCERT Page-317 / N-229
(a) 0.4
(b) 0.8
(c) 1.2
(d) 1.6
19. A glass slab of thickness 4cm contains the same number of waves as 5cm of water when both are traversed by the
same monochromatic light. If the refractive index of water is 4/3, what is that of glass? NCERT Page-317 / N-229
(a) 5/3
(b) 5/4
(c) 16/15
(d) 1.5
20. A ray of light is travelling from glass to air. (Refractive index of glass = 1.5 ). The angle of incidence is 50∘ . The
deviation of the ray is NCERT Page-317 / N-229
∘
(a) 0
(b) 80∘
sin 50∘
(c) 50∘ − sin−1 [ 1.5
]
sin 50 ∘
(d) sin−1 [ 1.5 ] − 50∘
21. A ray of light passes from vacuum into a medium of refractive index 𝜇, the angle of incidence is found to be twice the
angle of refraction. Then the angle of incidence is NCERT Page-317 / N-228
𝜇
(a) 2cos−1 ( 2 )
(b) sin−1 (𝜇)
𝜇
(c) sin−1 ( 2 )
𝜇
(d) cos−1 ( 2 )
RAY OPTICS AND OPTICAL
9 INSTRUMENTS
Exercise 1: NCERT Based Topic-wise MCQs
9.1 INTRODUCTION
1. Rectilinear propagation of light means NCERT Page-309 / N-221
(a) Light travels in straight lines
(b) Light travels in curved path
(c) Light travels in zig-zag path
(d) Light travels as a wave
9.2 REFLECTION OF LIGHT BY SPHERICAL MIRRORS
2. An object is placed 40cm from a concave mirror of focal.length 20cm. The image formed is
(a) real, inverted and same in size NCERT Page-312 / N-225
(b) real, inverted and smaller
(c) virtual, erect and larger
(d) virtual, erect and smaller
3. In image formation from spherical mirrors, only paraxial rays are considered because they
(a) are easy to handle geometrically NCERT Page-311 / N-222
(b) contain most of the intensity of the incident light
(c) form nearly a point image of a point source
(d) show minimum dispersion effect
4. For reflection through spherical surfaces, the normal at the point of incidence is NCERT Page-310 / N-222
(a) perpendicular to the principle axis and passes through the centre of curvature.
(b) perpendicular to the focal plane and passes through the pole.
(c) perpendicular to the tangent plane at pole and passes through the focus.
(d) perpendicular to the tangent plane at the point of incidence and passes through the centre of curvature.
5. Figure shows two rays 𝐴 and 𝐵 being reflected by a mirror and going as A′ and B ′ . The mirror
NCERT Page-312 / N-222
(a) is plane
(b) is convex
, (c) is concave
(d) may be any spherical mirror
6. Which of the following is incorrect statement? NCERT Page-314 / N-226
(a) the magnification produced by a convex mirror is always less than one
(b) a virtual, erect, same-sized image can be obtained using a plane mirror
(c) a virtual, erect, magnifield image can be formed using a concave mirror
(d) a real, inverted, same-sized image can be formed using a convex mirror
7. A rod of length 10cm lies along the principal axis of a concave mirror of focal length 10cm in such a way that its
end closer to the pole is 2Ωm away from the mirror. The length of the image is NCERT Page-314 / N-225
(a) 10cm
(b) 15cm
(c) 2.5cm
(d) 5cm
8. A car is fitted with a convexside-view mirror of focal length 20cm. A second car 2.8m behind the first car is
overtaking the first car at a relative speed of 15m/s. The speed of the image of the second car as seen in the mirror
of the first one is: NCERT Page-314 / N-225
1
(a) 15 m/s
(b) 10m/s
(c) 15m/s
1
(d) m/s
10
9. An object is moving with speed 𝑣0 towards a spherical mirror with radius of curvature 𝑅, along the central axis of the
mirror. The speed of the image respect to the mirror is ( 𝑈 is the distance of the object from mirror at any given time
𝑡) NCERT Page-314 / N-225
𝑅
(a) + ( ) 𝑣02
𝑈−2𝑅
𝑅 2
(b) − (𝑅−2𝑈) 𝑣0
𝑅 2
(c) − ( ) 𝑣0
2𝑈−2𝑅
𝑅
(d) + ( ) 𝑣02
2𝑈−2
10. A concave mirror is used for face viewing has focal length of 0.6m. At whay distance you should hold the mirror from
your face to get an upright image with a magnification of 4 ? NCERT Page-314 / N-226
(a) 0.20m
(b) 0.25m
(c) 0.40m
(d) 0.45m
11. A cube of side 2m is placed in front of a concave mirror of focal length 1m with its face 𝑃 at a distance of 3m and
face 𝑄 at a distance of 5m from the mirror. The distance between the image of face 𝑃 and 𝑄 is
(a) 1m NCERT Page-313 / N-225
(b) 0.5m
(c) 0.5m
(d) 0.25m
,12. A short linear object of length ℓ lies along the axis of a concave mirror of focal length 𝑓 at a distance 𝑢 from the pole
of the mirror. The size of the image is approximately equal to, NCERT Page-314 / N-225,226
𝑢−𝑓 1/2
(a) ℓ ( )
𝑓
𝑢−𝑓 2
(b) ℓ ( 𝑓 )
𝑓 1/2
(c) ℓ (𝑢−𝑓)
𝑓 2
(d) ℓ (𝑢−𝑓)
13. An object kept on the principle axis is moving in the same directions as that of mirror as shown in figure. Speed of
object and mirror is 10m/s and 40/12m/s. Radius of the curvature of the mirror is 20cm. What should be the
distance of object from the mirror at this instant so that the image is statonary? NCERT Page-314/ N-225
(a) 25cm
(b) 45cm
(c) 37.5cm
(d) 15cm
14. You are asked to design a shaving mirror assuming that a person keeps it 10cm from his face and views the
magnified image of the face at the closest comfortable distance of 25 cm. The radius of curvature of the mirror
would then be':
(a) 60cm
(b) −24cm
(c) −60cm
(d) 24cm
15. In figure find the total magnification after two successive reflections first on 𝑀1 and then on 𝑀2 .
if NCERT Page-314./ N-226
(a) +1
(b) -2
(c) +2
(d) -1
9.3 REFRACTION
16. As shown in the figure, after passing through the medium 1 . The speed of light 𝑣2 in medium 2 will be :
, (Given c = 3 × 108 ms−1 ) NCERT Page-317 /N − 228
(a) 1.0 × 108 ms −1
(b) 0.5 × 108 ms−1
(c) 1.5 × 108 mg −1
(d) 3.0 × 108 ms−1
17. Light travels through a glass plate of thickness 𝑡 and refractive index 𝜇. If 𝑐 is the speed of light in vacuum, the time
taken by light to travel this thickness of glass is NCERT Page-317 / N-229
(a). 𝜇tc
𝑡𝑐
(b) 𝜇
𝑡
(c) 𝜇𝑐
𝜇𝑡
(d)
𝑐
18. One face of a rectangular glass plate 6cm thick is silvered. An object held 8cm in front of the first face, forms an
image 12cm behind the silvered face. The refractive index of the glass is NCERT Page-317 / N-229
(a) 0.4
(b) 0.8
(c) 1.2
(d) 1.6
19. A glass slab of thickness 4cm contains the same number of waves as 5cm of water when both are traversed by the
same monochromatic light. If the refractive index of water is 4/3, what is that of glass? NCERT Page-317 / N-229
(a) 5/3
(b) 5/4
(c) 16/15
(d) 1.5
20. A ray of light is travelling from glass to air. (Refractive index of glass = 1.5 ). The angle of incidence is 50∘ . The
deviation of the ray is NCERT Page-317 / N-229
∘
(a) 0
(b) 80∘
sin 50∘
(c) 50∘ − sin−1 [ 1.5
]
sin 50 ∘
(d) sin−1 [ 1.5 ] − 50∘
21. A ray of light passes from vacuum into a medium of refractive index 𝜇, the angle of incidence is found to be twice the
angle of refraction. Then the angle of incidence is NCERT Page-317 / N-228
𝜇
(a) 2cos−1 ( 2 )
(b) sin−1 (𝜇)
𝜇
(c) sin−1 ( 2 )
𝜇
(d) cos−1 ( 2 )
