Page 2 - Worksheet 1

9. 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
10. 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

11. 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
12. The image formed by concave mirror is real, inverted and of the same size as that of the
object. The position of object should be
(a) at the focus

(b) at the centre of curvature
(c) between focus and centre of curvature
(d) beyond centre of curvature
13. 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
14. A10 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
[NCERT Exemplar Problems]
(a) – 30 cm
(b) – 20 cm
(c) – 40 cm
(d) – 60 cm