Question

A monochromatic beam of light passes from a denser medium into a rarer medium. As a result of which __.

• A. Its speed increases
• B. Its speed decreases
• C. Its frequency decreases
• D. Its wavelength increases

Answer 1

Answer: (A)

. Its speed increases.

When light travels from a denser medium to a rarer medium its speed increases. The frequency of light does not change because it depends upon the source.

$v=f\lambda$

or, $f=\frac{v}{\lambda }$, where v is the speed of light in medium

$\lambda$ is the wavelength of light

f is the frequency of light.

Since, f is constant.

If speed increases, wavelength also increases.

Hence, option 4 is incorrect.