Question

A converging lens has a focal length of 30 cm. A 5 cm tall candle is placed at a distance of 10 cm in front of the lens. Determine the image distance.

Answer 1

$1/d_i+1/d_o=1/f\to1/d_i=1/f-1/d_o=1/0.3-1/0.1=-6.6667\to$

$d_i=1/(-6.6667)=-0.15\ (m)=-15\ (cm)$ . Answer