Question

An object is placed at a distance of 20 cm from the pole of a concave mirror of focal length 10 cm. The distance of the image formed is

• A. + 20 cm
• B. + 10 cm
• C. - 20 cm
• D. - 10 cm

Answer 1

Answer: (C)

- 20 cm

Answer 2

$\frac{1}{f} = \frac{1}{v} +\frac{1}{u}$
$\frac{1}{-10} = \frac{1}{v}- \frac{1}{20}$
$\frac{1}{v} = \frac{1}{20}-\frac{1}{10}= \frac{10-20}{200}$
$v = -20 \,cm$