Question

A man holds a spherical shaving mirror of radius of curvature 60 cm, and focal length 30 cm, at a distance of 15 cm, from his nose. Find the position of image, and calculate the magnification. 

Answer 1

Distance of the object, i.e. nose, from the mirror (u) = -15 cm
The focal length of the concave mirror (f) = -30 cm

We have to find the distance of the image (v).

Using the mirror formula, we get  

`1/f=1/v+1/u` 

`1/-30=1/v-1/15` 

`or 1/v=1/15-1/30` 

`or 1/v=(2-1)/30` 

`or 1/v=1/30` 

v=30 cm  

Thus, the position of the image is 30 cm behind the mirror.

Now, using the magnification formula, we get 

`m=(-v)/u` 

`m=(-30)/-15=2` 

Therefore, the image is 2 times magnified than the object.