A convex mirror used as a rear view mirror in an automobile has a radius of curvature 2 m. If the bus is located at a distance of 6 m from the mirror, find the position, nature and the size of the image.

Solution : 

Radius of curvature of the convex mirror R = 2 m
Focal length of the convex mirror f = R/2 = 1 m  (positive for convex mirror)

Object (bus) distance u = − 6 m
Image distance v = ?
Mirror formula is:
1/f = 1/v + 1/u
1/1 = 1/v + 1/(−6)
1/v = 1 + 1/6
 1/v  = 7/6
 v = 0.85 m
Position of the image is at 0.85 m behind the mirror.
Magnification, m = - v/u
m = - (0.85)/- 6
m = 0.14 
The image will be diminished.