Question

An arrow is placed at a distance of 25 cm from a diverging mirror of focal length 20 cm. Find the image distance.

• A. $12.1cm$
• B. $13.1cm$
• C. $11.1cm$
• D. $14.2cm$

Answer 1

The correct option is C $11.1cm$

Given,

$u=-25cm$ (the minus sign indicates the object is placed in front of the mirror)

$f=+20cm$ (plus sign is for a diverging mirror)

$v=?$

From the mirror formula,

$\frac{1}{f}=\frac{1}{u}+\frac{1}{v}$

$\Rightarrow \frac{1}{20}=\frac{1}{-25}+\frac{1}{v}$

$\Rightarrow \frac{1}{v}=\frac{9}{100}$

$\Rightarrow v=\frac{100}{9}cm$

$\therefore v=11.1cm$

The correct option is C.