Question

a bicnvex lens of radii 5 cm of 5 diopter power then what is the refractive index of the lens​....dont answer plz​

Answer 1

Power lens,

P (in dioptre) = 100 / focal length f (in cm)

Therefore , f = 100 / 5 = 20 cm

So , the solution will be

According to lens maker's formula,

1/f = (μ - 1) [ (1/R₁) - (1/R₂) ]

For biconvex lens, R₁ = +R , R₂ = R

1/f = (μ - 1) [ (1/R) + (1/R) ]

1/f = (μ - 1) [ (2/R) ]

1/5 = (μ - 1) [ (2/5) ]

(μ - 1) = 1/2

μ = 1/2 + 1

μ = 3/2

The refractive index of the lens is 3/2