The radius of curvature of the faces of a double convex lens are `10 cm and 15 cm`. If focal length of lens of lens is `12 cm`, find the refractive index of the material of th lens.

Answer

`1.5`

Explanation

Here, `R_(1) = 10 cm, R_(2) = - 15 cm, f = 12 cm`,
`mu = ?`
From lens maker's formula
`(1)/(f) = (mu - 1)((1)/(R_(1)) - (1)/(R_(2)))`
`(1)/(12) = (mu - 1)((1)/(10) + (1)/(15)) = (mu - 1)(1)/(6)`
`mu - 1 = (6)/(12) = (1)/(2), mu = (1)/(2) + 1 = (3)/(2) = 1.5`