Question

A concave mirror produces three times enlarged virtual image of an object placed at 10 cm in front of it. Calculate the radius of curvature of the mirror.

Answer 1

Given:

Magnification produced by mirror,(m)A= +3
Object Distance = u= -10cm( sign conventions)
Distance of the image(v)=?
Formula to be used: m= -V/u
-v= m x u
-v= 3×-10
v=30 cm
Now to find focal length, we use mirror formula:

1/f = 1/v + 1/u
1/f = 1/30 +1/(-10)
1/f=(1-3)/30
1/f=-2/30
1/f=-1/15
f = -15cm.
Since object is placed at 10cm which is less than focal length.

So we can say, the object is placed between Pole and Focus. So, we get virtual,enlarged and erect image.

Radius of curvature (R)= 2f
R= 2x-15
R=-30cm.