Question

Define the term magnification as referred to spherical mirrors. If a concave mirror forms a real image 40 cm from the mirror, when the object is placed at a distance of 20 cm from its pole, find the focal length of the mirror.

Answer 1

The relative extent to which the image of an object is magnified with respect to object size. It is the ratio of size of the image to the size of the object.

v = – 40 cm, u = –20 cm, f = ? 

1/ f = 1/ v +1/ u

1/ f = – 1 / 40 + – 1 / 20 

f= - 40 /3cm