Find the refractive index of the glass which a symmetrical convergent lens of its focal lengths is is equal to the radius of curvature of its surface. (A57)

Using formula: Lens Maker’s Formula:

f = focal length

R₁ = radius of curvature of the lens surface closer to the source of light

R₂ = radius of curvature of the lens surface farther to the source of light

n = Refractive index

Given: The lens is symmetrical. Therefore R₁ = R₂

According to sign convention: R₁ = R & R₂ = -R

focal length (f) = Radius of curvature(R)

2n-2 = 1

2n = 3

n = 3/2 = 1.5

n = Refractive index = 1.5