Question

A concave mirror for face viewing has focal length of 0.4 m. The distance at which you hold the mirror from your face in order to see your image upright with a magnification of 5 is:
(A) 0.16 m (B) 1.60 m
(C) 0.24 m (D) 0.32 m

Answer 1

ANSWER

m=f−uf

5=−40−u−40

u=−32cm

Answer 2

The distance at which you should hold the mirror from your face in order to see your image upright with a magnification of 5 is:

(D) 0.32 m

This can be calculated in the following ways:

• Magnification can be represented as -

        m=(f−u) / f​

• As per the question, m = 5 , f = 0.4 m = 40 cm

• Now, 5 = (−40−u) / −40​

       u = −32cm

• Thus, the distance is 0.32 m.

• The negative sign shows that the object is in front of a concave mirror.