Question

An object is kept at a distance 20 cm from a concave mirror of focal length 10 cm. The position of image will be what ?

Answer 1

Explanation:

Given:

 Focal length of concave mirror, f = -20 cm

Distance of object from the mirror, u = -10 cm

use formula, 1/v + 1/u = 1/f 

or, 1/v = 1/f - 1/u 

or, 1/v = 1/-20 - 1/-10 

or, 1/v = -1/20 + 1/10 = 1/20 

or, v = +20cm 

hence, image position is the 20cm right side from the pole of the concave mirror as shown in the diagram. The image is straight and bigger than the object.