Question

Lightwaves travel from the air into a lens made of glass. Their velocity decrease as they enter the glass. How does this effect the frequency and wavelength of the lightwaves?

Answer 1

Light waves travel from the air into a lens made of glass.
Their speed decreases as they enter the glass.

When that happens, the frequency of the waves doesn't change,
but their wavelength gets longer.

Answer 2

1. The frequency is unchanged

2. The wavelength decreases or is reduced

Step-by-step explanation:

When light waves travel from air into glass, this is a phenomenon of light waves travelling from a less dense medium (air) to a denser medium (glass).

First thing is that the velocity (speed) of the light wave will be reduced as it crosses into the glass medium

Research has shown that when visible light travels from air into a medium such as glass, it loses velocity and only retains 75% of it's initial velocity in air, however, the energy is unchanged.

As light crosses into the medium of glass, the wavelength decreases and the light wave changes direction. This is responsible for refraction.

Finally, the frequency of the light wave is unaffected i.e. unchanged.

Using Equation;

v = f λ

where v = velocity

f = frequency

and λ = wavelength

From the above equation, we can verify that the change in velocity is proportional to the change in wavelength while frequency remains constant.