Question

A concave mirror forms a 3 times inverted
image of an object. The distance from the
object to its image is 28 cm. Determine the
principal focal length of the mirror

Answer 1

Explanation:

let height of object is" x "cm.

height of image is - 3x (because image is inverted)

now "U=-28cm

By m=-v/u=h2/h1

v=-84

by mirror formula to find F=1/v+1/U=1/F

so principal axis is=21cm Ans