A 4 cm axial rod is centred 30 cm from a concave mirror of focal length 20 cm. Its ends are therefore 28 cm and 32 cm from the pole. Find the exact image length in centimetres.
Physics · Geometrical optics · spherical mirror
JEE Mains NEET

Question

A 4 cm axial rod is centred 30 cm from a concave mirror of focal length 20 cm. Its ends are therefore 28 cm and 32 cm from the pole. Find the exact image length in centimetres.

G1 Physics · Accepted Answer

v(28)=20×28/8=70 cm and v(32)=20×32/12=53.333 cm. The image length magnitude is 16.667 cm.