Class - XII Optics Physics (S-2)
1. A thin lens of refractive index 1.5 has a focal length of 15 cm in air. When the lens is placed in a medium of
refractive index 4/3, find out focal length in water. (60 cm)
2. A convex lens of focal length 40 cm, a concave lens of focal length 40 cm and a concave lens of focal length
15 cm are placed in contact. Find out power of the combination. (-6.67 D)
3. A ray of light is incident normally as one of the faces of a prism of apex angle 30° and refractive index √2.
Find out angle of deviation. (15® )
4. Two lenses of power - 15 D and + 5 D are in contact with each other. Find out he focal length of the
combination. (-10 cm)
5. The figures represent three cases of a ray passing through a prism of refracting angle A. The case
corresponding to minimum deviation is (3 only)
6. The angle of a prism is 30°. The ray incident at 60° on one refracting face suffers a deviation of 30°. Then find
the angle of emergence. (0®)
7. The angle of prism is 60°. What is the angle of incidence for minimum deviation? (45®)
(The refractive index of material of prism is √2).
8. A convex spherical surface separates object and image space of refractive index 1.0 and 1.33. If radius of
curvature of the surface is 0.1 m, find out its power. (2.48 D)
9. A convex lens of power + 6 dioptre is placed in contact with a concave lens of power - 4 dioptre. What will be
the nature and focal length of this combination? (convex, 50 cm)
10. A thin glass (refractive index 1.5) lens has optical power of – 5 D in air. Its optical power in a liquid medium
with refractive index 1.6 will be (5/8 D)
11. What is the position and nature of image formed by lens combination shown in figure given below? (f₁, f₂ are
focal lengths): (70 cm from point B at right; real)
1. A thin lens of refractive index 1.5 has a focal length of 15 cm in air. When the lens is placed in a medium of
refractive index 4/3, find out focal length in water. (60 cm)
2. A convex lens of focal length 40 cm, a concave lens of focal length 40 cm and a concave lens of focal length
15 cm are placed in contact. Find out power of the combination. (-6.67 D)
3. A ray of light is incident normally as one of the faces of a prism of apex angle 30° and refractive index √2.
Find out angle of deviation. (15® )
4. Two lenses of power - 15 D and + 5 D are in contact with each other. Find out he focal length of the
combination. (-10 cm)
5. The figures represent three cases of a ray passing through a prism of refracting angle A. The case
corresponding to minimum deviation is (3 only)
6. The angle of a prism is 30°. The ray incident at 60° on one refracting face suffers a deviation of 30°. Then find
the angle of emergence. (0®)
7. The angle of prism is 60°. What is the angle of incidence for minimum deviation? (45®)
(The refractive index of material of prism is √2).
8. A convex spherical surface separates object and image space of refractive index 1.0 and 1.33. If radius of
curvature of the surface is 0.1 m, find out its power. (2.48 D)
9. A convex lens of power + 6 dioptre is placed in contact with a concave lens of power - 4 dioptre. What will be
the nature and focal length of this combination? (convex, 50 cm)
10. A thin glass (refractive index 1.5) lens has optical power of – 5 D in air. Its optical power in a liquid medium
with refractive index 1.6 will be (5/8 D)
11. What is the position and nature of image formed by lens combination shown in figure given below? (f₁, f₂ are
focal lengths): (70 cm from point B at right; real)
