The refractive index of the material of a double convex lens is 1.5 and its focal length is 5cm. If the radius of curvature of faces are equal, what is the radius of curvature?

1 Answer
Jul 22, 2018

The radius of curvature is #=5cm#

Explanation:

The refractive index is

#n=1.5#

The focal length is

#f=5cm#

The radius of curvatures are

#r=r_1=-r_2#

Apply the thin lens approximation

#1/f=(n-1)(1/r_1-1/r_2)=(n-1)(2/r)#

Therefore,

#1/5=(1.5-1)*2/r#

#r=10*0.5=5cm#