LIGHT
SHORT ANSWER TYPE QUESTIONS [II] [3 Marks]
1. A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so
that it forms an image at 15 cm from the lens? Also calculate the size of the image formed.
Answer.
LONG ANSWER TYPE QUESTION [5 Marks]
3. Draw the ray diagram in each case to show the position and nature of the image formed when the object is
placed:
(i) at the centre of curvature of a concave mirror
(ii) between the pole P and focus F of a concave mirror
(iii) in front of a convex mirror
(iv) at 2F of a convex lens
(v) in front of a concave lens
Answer.
Nature of image: Real, inverted and same size image is formed at the centre of curvature.
Nature of image: Virtual, enlarged and erect image is formed behind the mirror.
,Nature of image: Virtual, erect and diminished, image is formed behind the mirror.
Nature of image: Real, inverted and size to size, image is formed at 2F on the other side of lens.
Nature of image: Virtual, erect and diminished image is formed between O and F on the same side of object.
VERY SHORT ANSWER TYPE QUESTIONS [1 Mark]
4. If a light ray IM is incident on the surface AB as shown, identify the correct emergent ray.
Answer. Ray NQ, as it has to be parallel to ray OS.
5. The refractive indices of four media A, B, C and D are given in the following table:
If light, travels from one medium to another, in which case the change in speed will be (i) minimum, (ii)
maximum?
Answer. (i) Minimum change is seen as light moves between 1.50 and 1.52, i.e. B and C.
(ii) Maximum change when light moves between 1.33 and 2.40, i.e. A and D.
, 6. “The refractive index of diamond is 2.42”. What is the meaning of this statement in relation to speed of
light?
Answer.
7. Redraw the given diagram and show the path of the refracted ray:
Answer.
8. Redraw the given diagram and show the path of the refracted ray:
Answer.
9. Draw the following diagram in your answer book and show the formation of image of the object AB with
the help of suitable rays.
SHORT ANSWER TYPE QUESTIONS [II] [3 Marks]
1. A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so
that it forms an image at 15 cm from the lens? Also calculate the size of the image formed.
Answer.
LONG ANSWER TYPE QUESTION [5 Marks]
3. Draw the ray diagram in each case to show the position and nature of the image formed when the object is
placed:
(i) at the centre of curvature of a concave mirror
(ii) between the pole P and focus F of a concave mirror
(iii) in front of a convex mirror
(iv) at 2F of a convex lens
(v) in front of a concave lens
Answer.
Nature of image: Real, inverted and same size image is formed at the centre of curvature.
Nature of image: Virtual, enlarged and erect image is formed behind the mirror.
,Nature of image: Virtual, erect and diminished, image is formed behind the mirror.
Nature of image: Real, inverted and size to size, image is formed at 2F on the other side of lens.
Nature of image: Virtual, erect and diminished image is formed between O and F on the same side of object.
VERY SHORT ANSWER TYPE QUESTIONS [1 Mark]
4. If a light ray IM is incident on the surface AB as shown, identify the correct emergent ray.
Answer. Ray NQ, as it has to be parallel to ray OS.
5. The refractive indices of four media A, B, C and D are given in the following table:
If light, travels from one medium to another, in which case the change in speed will be (i) minimum, (ii)
maximum?
Answer. (i) Minimum change is seen as light moves between 1.50 and 1.52, i.e. B and C.
(ii) Maximum change when light moves between 1.33 and 2.40, i.e. A and D.
, 6. “The refractive index of diamond is 2.42”. What is the meaning of this statement in relation to speed of
light?
Answer.
7. Redraw the given diagram and show the path of the refracted ray:
Answer.
8. Redraw the given diagram and show the path of the refracted ray:
Answer.
9. Draw the following diagram in your answer book and show the formation of image of the object AB with
the help of suitable rays.
