Question

Find out the image position formed by concave mirror, considering the image formed by mirror as an object for concave mirror.

• A. 20 $cm$, from the pole.
• B. 30 $cm$, from the pole.
• C. 40 $cm$, from the pole.
• D. 60 $cm$, from the pole.

Answer 1

The correct option is B

30 $cm$, from the pole.

Using Mirror Formula,
Sign conventions for u = -ve ( Left side of the mirror)
f = -ve ( Concave mirror)
$\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$
$\frac{1}{v}+\frac{1}{-60}=\frac{-1}{20}$

$\frac{1}{v}=\frac{1-3}{60}$

v = $-30cm$

i.e. $30cm$ from the pole. (left side of the mirror)