Question

When light is refracted from air into glass

• A. Its wavelength increase but frequency remain unchanged
• B. Its wavelength and frequency both decrease
• C. Its wavelength decrease but frequency remain unchanged
• D. Its wavelength and frequency both increase

Answer 1

The correct option is C

Its wavelength decrease but frequency remain unchanged

The explanation of the correct option:

Refraction

1. Refraction is the term used to describe the way light bends as it penetrates a piece of glass.
2. While frequency is a fundamental characteristic of a light ray, refraction is caused by a change in wavelength as a result of a change in the speed of light in another medium.

Relation between the medium's wavelength, frequency, and the speed of light can be given as

$v=f\lambda$

Where,

$\lambda$ is the wavelength of the light in that medium.

$f$ is the inherent quality of the light ray, which is unaffected by the medium.

$\mathrm{\mu }\propto \frac{1}{\mathrm{\lambda }}$

as, ${\mathrm{\lambda }}_{\mathrm{b}}<{\mathrm{\lambda }}_{\mathrm{g}}$

but, $\mathrm{fb}=\mathrm{fg}$

The wavelength of light decreases but the frequency does not when light is refracted from the air into a glass.

The explanation for the incorrect options:

All three options A, B, and D are incorrect because the energy contained with a photon of this light is proportional to the frequency of the light and is not affected by the medium into which it is refracted, although the speed of the light changes, the frequency does not.

Therefore the correct option is C.