The power of a biconvex lens is 10 dioptre and the radius of curvature of each surface is 10   cm . Then the refractive index of the material of the lens is,

Step-by-step solution

Recall the proper relation between power and focal length, P = 100 f ⇒ f = 100 P = 100 10 = 10   cm , now the relation between focal length and radius of curvature and refractive index, of the spherical surface lens, f = R 2 ( μ - 1 ) (for equiconvex lens) ⇒ 10 = 10 2 ( μ - 1 ) ⇒ ( μ - 1 ) = 1 2 ⇒ μ = 1 2 + 1 = 3 2 .