NEET | 2018Geometrical OpticsHard

Question

An object is placed at a distance of 40 cm from a concave mirror of focal length 15 cm. If the object is displaced through a distance of 20 cm towards the mirror, the displacement of the image will be:-

Options

A.

30 cm away from the mirror

B.

36 cm away from the mirror

C.

30 cm towards the mirror

D.

36 cm towards the mirror

Solution


(i)

v1=ufu-f=(-40)(-15)-40+15=600-25=-24cm
(ii)

V2=ufu-f=(-20)(-15)-20+15=-60cm
Displacement of image = v2 - v1 = - 36 cm
= 36 cm away from the mirror

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