Question

An object 0.04m high is placed in front
of and at right angles to the axis of a
concave mirror which has radius of
curvature 0.15m. If a real image 0.12m
high is obtained, determine by scale
drawing or otherwise,
1. the distance of the object from the
mirror
2. how far, and in what direction, must
the object be moved in order to obtain
a virtual image 0.12m high.

Answer 1

1. The focal length of mirror is equal to

$f=\frac{0.15}{2}=0.075 m$

In our case, we can write formula for concave mirror as

$\frac{1}{f}=\frac{1}{v}+\frac{1}{u} (1)$

In our case, we have f=0.075 m, v=0.12 m

Using (1) we get

v=0.2 m

Answer

0.2 m

2. In our case, we have f=0.075 m, u=-0.12 m

Using (1) we get

v=0.046 m

The object must be placed between the mirror and its focus.

Answer

0.046 m

The object must be placed between the mirror and its focus.