Question

A small candle, 2.5 cm in size is placed at 27 cm in front of a concave mirror of radius of curvature 36cm, at what distance from the mirror should a screen be placed in order to obtain a sharp image.

Answer 1

$$u=-27\ cm,R=-36\ cm,f=0.5R=-18\ cm$$

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

$$\frac{1}{-18}=\frac{1}{-27}+\frac{1}{v}$$

$$v=-54\ cm$$