Question

A converging mirror forms a real image of height 3 cm of an object of height 1 cm placed 20 cm away from the mirror. Calculate the image distance and focal length of the mirror​

Answer 1

Answer:

Answer is 16 cm

Explanation

Magnification m = $\frac{-v}{u}$

-4 = $\frac{-v}{-20}$

v = -80 cm

From mirror formula

$\frac{1}{v} +\frac{1}{u} = \frac{1}{f} \\\frac{1}{-80} + \frac{1}{-20} =\frac{1}{f} \\\frac{1}{f} = \frac{1+4}{-80} \\f = -16 cm$

Thus the focal length of converging mirror  is 16 cm