Page 1 - HA-sign convention rules of sph lens

MCQ (BOARD)

1. A lens of focal length 12 cm forms an erect image, three times the size of the
object. The distance between the object and image is:

(a) 8 cm

(b) 16 cm

(c) 24 cm

(d) 36 cm

2. If an object is placed 21 cm from a converging lens, the image formed is slightly

smaller than the object. If the object is placed at a distance of 19 cm from the lens,

the image formed is slightly larger than the object. The approximate focal length of
the lens is:

(a) 20 cm

(b) 18 cm

(c) 10 cm

(d) 5 cm

3. An image of a pencil is formed at a distance of 10 cm from the concave lens of

focal length 15 cm. The object distance is

a) 15 cm.

b) + 15 cm.

c) 30 cm.
d) + 30 cm.

4. The focal length of a concave lens is 20 cm. An object is placed before the lens at
40 cm, the image is

a) larger than the object.
b) of the same size as the object.

c) formed at 25 cm from the lens on the other side.

d) smaller than the object.