Question

When a light wave travels from air to glass ______.

Options

• its wavelength decreases

• its wavelength increases

• there is no change in wavelength

• its frequency decreases

Answer 1

When a light wave travels from air to glass its wavelength decreases.

Explanation:

When light travels from air (rarer medium) to glass (denser medium), its speed decreases, so according to the relation (v = f λ) (speed = frequency × wavelength) and the fact that frequency remains constant, the wavelength must decrease in glass. Hence, the light wave’s wavelength decreases when passing from air to glass.