A small insect starts walking away from a concave mirror along its principal axis. At a point (P) 20 cm from the mirror the image flips upside down. (a) What can you say about the size of the image at the instant it flips upside down – it is very large, very small or of the size similar to the insect? (b) Find the distance of the insect from point (P) where its image is thrice as large as the insect.

Answer

(a) very large (b) 6.67 cm on both sides of P.