Question

A ray of light of wavelength 600 nm propagates from air into a medium. If its wavelength in the medium becomes 400 nm, the refractive index of the medium is ______.

Options

• 1.4

• 1.5

• 1.6

• 1.8

Answer 1

A ray of light of wavelength 600 nm propagates from air into a medium. If its wavelength in the medium becomes 400 nm, the refractive index of the medium is 1.5.

Explanation:

We know that refractive index and wavelength have an inverse relation. Therefore, the refractive index is stated to be inversely proportional to the wavelength.

`n = c/(flambda)`

Given: `lambda_1 = 600  "nm", lambda_2 = 400  "nm"`

To find: Refractive index (n)

`n_1lambda_1 = n_2lambda_2`

`n_2/n_1 = lambda_1/lambda_2`

`n_2 = 600/400` [∵ n₁ = 1]

`n_2 = 1.5`