Question

A concave mirror is made by a cutting a portion of hollow glass sphere of radius 30 cm. find the focal
length of mirror.

Answer 1

Answer:

so given,r= 30 cm

so focus = r/2 so 30/2 = 15

so we know that focus length from pole to focus

so focal length = radius of curvature- focus

30-15 =15

therefore,focal length= 15