MCQ type:

1. Which type of mirror is used to get a virtual, erect, laterally inverted and same size image as that of
object?

(a) Convex mirror (b) Concave mirror

(c) Plane mirror (d) All of these

2. In reflection of light, the angle of reflection is

_______ the angle of incidence.

(a) equal to (b) greater tnan

(c) less than (d) cannot say

3. The angle between the incident ray and reflected ray is 60°, the angle of incidence is

(a) 60° (b) 45°

(c) 30° (d) 90°

4. A ray of light is incident on a plane reflecting surface at angle of incidence of 30°. Then the reflected
ray is deviated by an angle equal to

(a) 30° (b) 150°

(c) 60° (d) 120°

5. The angle of incidence for a ray of light having zero reflection angle is

(a) 90° (b) 45° (c) 30° (d) 0°

6. A concave mirror of radius 30 cm is placed in water.

It’s focal length in air and water differ by

(a) 15 (b) 20

(c) 30 (d) 0

7. A real image is formed by the light rays after reflection or refraction when they:

(A) actually meet or intersect with each other.

(B) actually converge at a point.

(C) appear to meet when they are produced in the backward direction.

(D) appear to diverge from a point.

Which of the above statements are correct?

(a) (A) and (D) (b) (B) and (D)

(c) (A) and (B) (d) (B) and (C)

8. When an object is kept within the focus of a concave mirror, an enlarged image is formed behind the
mirror. This image is:

(a) real

(b) inverted

(c) virtual and inverted

(d) virtual and erect

9. For a real object, which of the following can produce a real image?

(a) Plane mirror (b) Concave mirror

(c) Concave lens (d) Convex mirror

10. The nature of the image formed by concave mirror when the object is placed between the focus (F)
and centre of curvature (C) of the mirror observed by us is

(a) real, inverted and diminished

(b) virtual, erect and smaller in size

(c) real, inverted and enlarged

(d) virtual, upright and enlarged

11. The radius of curvature of a converging mirror is 30 cm. At what distance from the mirror should an
object be placed so as to obtain a virtual image?

(a) Infinity

(b) 30 cm

(c) Between 15 cm and 30 cm

(d) Between 0 cm and 15 cm

12. An object at a distance of 30 cm from a concave mirror gets its image at the same point. The focal
length of the mirror is

(a) – 30 cm (b) 30 cm

(c) – 15 cm (d) +15 cm

13. The nature of image formed by a convex mirror when the object distance from the mirror is less than
the distance between pole and focal point (F) of the mirror would be

(a) real, inverted and diminished in size

(b) real, inverted and enlarged in size

(c) virtual, upright and diminished in size

(d) virtual, upright and enlarged in size

14. An object at a distance of +15 cm is slowly moved towards the pole of a convex mirror. The image
will get

(a) shortened and real

(b) enlarged and real

(c) enlarge and virtual

(d) diminished and virtual

15. On moving the object from infinity towards the pole

of the convex mirror, the image moves from

(a) focus towards pole

(b) focus towards centre of curvature

(c) pole to infinity on the same side of object

(d) focus to infinity behind the mirror

16. If the object moves away from the pole of a convex mirror, then, the size of image gradually changes
from

(a) highly enlarged to enlarged

(b) diminished to point size

(c) highly diminished to diminished

(d) highly diminished to same size of object

17. A concave mirror of focal length 20 cm forms an image having twice the size of object. For the virtual
position of image, the position of object will be at

(a) 25 cm (b) 40 cm

(c) 10 cm (d) At infinity

18. If a man’s face is 25 cm in front of concave shaving mirror producing erect image 1.5 times the size
of face, focal length of the mirror would be

(a) 75 cm (b) 25 cm

(c) 15 cm (d) 60 cm

19. What is the position of the object placed on the side of reflecting surface of a concave mirror of focal
length 15 cm if the image is formed at the distance of 30 cm from the mirror?

(a) 15 cm (b) 30 cm

(c) 25 cm (d) 40 cm

20. An object of height 4 cm is kept at a distance of 30 cm from the pole of a diverging mirror. If the
focal length of the mirror is 10 cm, the height of the image formed is

(a) + 3.0 cm (b) + 2.5 cm

(c) + 1.0 cm (d) + 0.75 cm

21. A spherical mirror and a thin spherical lens have each a focal length of -15cm. The mirror and 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 and the lens is concave

22. 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 5cm.

(B) A concave lens of focal length 5cm.

(e) A convex lens of focal length 50 cm.

(D) A concave lens of focal length 50 cm.

23. A real image is formed by the light rays after reflection or refraction when they:

(A) actually meet or intersect with each other.

(B) actually converge at a point.

(C) appear to meet when they are produced in the backward direction.

(D) appear to diverge from a point.

Which of the above statements are correct?

(a) (A) and (D)

(b) (B) and (D)

(c) (A) and (B)

(d) (B) and (C)

24. A light ray incident on a rectangular glass slab, after emerging from the opposite parallel faces, it is
found that the

(a) ∠i > ∠e (b) ∠i < ∠e

(c) ∠i = ∠e (d) ∠i ≠ ∠e

where ∠i = angle of incidence

∠e = angle of emergence

25. A ray of light falling on a glass slab at 90°. The angle of incidence is

(a) 90° (b) zero

(c) < 90° ≠ 0 (d) greater then 90°

26. Mohit took a thick glass slab whose one opposite parallel face is silvered. He observed that it formed
multiple images. This happened on account of

(a) refraction of light

(b) reflection of light

(c) dispersion of light

(d) both (a) and (b)

27. Snell’s law can be derived from which type of incidence of light ray?

(a) Angle of refraction

(b) Angle of incidence

(c) Oblique incidence

(d) Angle of reflection

28. When an incident ray of light enters a medium from air, it bends towards the normal. Which of the
following is TRUE about the refractive index of the medium (nm) as compared to the refractive index of
air (na)?

(a) nm is equal to na

(b) nm is less than na

(c) nm is more than na

(d) The refractive indices cannot be compared based on the given information.

29. When object moves closer to convex lens, the image formed by it shift

(a) away from the lens

(b) towards the lens

(c) first towards and then away from the lens

(d) first away and then towards the lens

30. When object moves closer to a concave lens the image formed by it shifts

(a) away from the lens on the same side of object

(b) toward the lens

(c) away from the lens on the other side of lens

(d) first towards and then away from the lens

31. 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 tens

(B) At twice the focal length.

(c) At infinity
(D) Between the optical centre of the lens and its principal focus.

32. Person suffering from catract has

(A) excessive curvature of eye lens

(B) opaque eye lens

(C) elongated eyeball

(D) Weakened ciliary muscles.

33. A person can not see objects distinctly kept beyond 2 m. This defect can be corrected by using a lens
of power

(A) +0.5D

(B) - 0.5D

(C) +0.2D

(D) -0.2D.

34. If the power of lens is –4.0D, then it means that the lens is a

(a) concave lens of focal length –50 m

(b) convex lens of focal length +50 cm

(c) concave lens of focal length –25 cm

(d) convex lens of focal length –25 cm

35. In which of the following devices, convex lens is not used?

(a) Magnifying glass (b) Microscope

(c) Flashlights (d) Telescope

36. Two convex lens P and Q have focal length

0.50 m and 0.40 m respectively.

Which of the following is TRUE about the combined power of the two lenses?

(a) P is equal to 4.5 D.

(b) P is less than 4.5 D.

(c) P is more than 4.5 D.

(d) P cannot be determined from the information given.

37. The combination of spherical lens of power +3D and –3D acts as a

(a) bifocal lens of power 6D

(b) plane glass sheet/slab

(c) convex lens having no power

(d) concave lens of power – 6D

38. The focal length of four convex lens P, Q, R and S are 20 cm, 15 cm, 5 cm and 10 cm respectively. The
lens having lowest power is

(a) P (b) Q

(c) R (d) S

39. No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be

(a) only plane.

(b) only concave.

(c) only convex.

(d) only either plane or convex.

40. When a ray passing through focus strikes concave lens, the refracted ray will

(a) retrace its path

(b) emerge parallel to the principal axis

(c) emerge perpendicular to the principal axis

(d) emerge through a focus on another side

Short Answer type:-

1. State any three difference between real image and virtual image formed by a spherical mirror.

2. With respect to air, the refractive index of ice is 1.31 and that of rock salt is 1.54. Calculate the
refractive index of rock salt with respect to ice.
3. The refractive index of a medium ‘x’ with respect to ‘y’ is 2/3 and the refractive index of medium ‘y’
with respect to ‘z’ is 4/3. Calculate the refractive index of medium ‘z’ with respect of ‘x’. If the speed of
light medium ‘x’ is 3 × 10^8 ms–1, calculate the speed of light in medium ‘y’.

4. State any three difference between a plane mirror and a spherical mirror.

5. 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.

6. On entering in a medium from air, the speed of light becomes half of its value in air. Find the
refractive index of that medium with respect to air?

7. Distinguish between a double convex lens and a double concave lens.

8. Discuss about the cause of Refraction.

9. Discuss about Persistance of vision.

10. What do you know about Power of accommodation of eye?

11. Distinguish between a convex and a concave mirror.

12. (a) Define unit of a power of a lens.

(b) A converging lens has a focal length of 250 mm.

Calculate its power and express it according to Sign Convention.

13. How are power and focal length of a lens related? You are provided with two lenses of focal length
20 cm and 40 cm respectively. Which lens will you use to obtain more convergent light?

14. Refractive index of diamond with respect to glass is 1.6 and absolute refractive index of glass is 1.5.
Find out the absolute refractive index of diamond.

15. Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The
speed of light in vacuum is 3 × 10^8 ms–1.

Long Answer type:

1. The image of a candle flame placed at a distance of 36 cm from a spherical lens is formed on a screen
placed at a distance of 72 cm from the lens. Identify the type of lens and calculate its focal length. If the
height of the flame is 2.5 cm, find the height of the image.
2. The size of image of an object by a mirror having a focal length of 20 cm is observed to be reduced to
1/3rd of its size. At what distance the object has been placed from the mirror? What is the nature of the
image and the mirror?

3. An object is placed at a distance of 30 cm from a Concave lens of focal length 30 cm, determine the
distance of image from the lens, list four characteristics of the image (nature, position, size,
erect/inverted) and draw a labelled diagram of it.

4. 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 the nature of the image formed.

5. 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.