Lateral magnification of an object by spherical mirror is 0.3. If focal length of mirror is 30 cm, find type of mirror.

Options

A. concave
B. convex
C. concave or convex
D. none of these

Answer

B, C

Explanation

Magnification for mirror,
`m=(f)/(f-u)=(f-v)/(f)`
(1) `m=(f)/(f-u)`
`therefore 0.3 =(30)/(30-u)`
`30-u=100`
`therefore u=-70` cm
`m=(f-v)/(f)
`therefore 0.3=(30-v)/(30)`
`therefore 9 =30-v`
`therefore v=21` cm
`therefore` Image obtained behind the mirror, hence convex.