First slide

Spherical/Curved mirrors

Question

A point object is placed at a distance of 10cm and its real image is formed at a distance of 20 cm from a concave mirror. If the object is moved by 0.1cm towards the mirror, the image will shift by about

Moderate

A

$0 .4 cm$ away from the mirror
B

0.4 cm towards the mirror
C

0.8 cm away from the mirror
D

0.8 cm towards the mirror

Solution

Mirror formula
$\frac{1}{f} = \frac{1}{v} + \frac{1}{u} \Rightarrow \frac{1}{f} = \frac{1}{- 20} + \frac{1}{(- 10)} \Rightarrow f = \frac{20}{3} cm$
If object moves towards the mirror by then.
$u = (10 - 0 .1) = 9 .9 cm$ .
Hence again from mirror formula $\frac{1}{- 20 / 3} = \frac{1}{v^{'}} + \frac{1}{- 9 .9} \Rightarrow v^{'} = 20 .4 cm$
i.e., image shifts away from the mirror by 0.4 cm.

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App