Question

An electromagnetic wave of frequency v = 3 MHz passes from vacuum into dielectric medium with permittivity $ϵ=4.0$ Then

• A. the wavelength is doubled and the frequency becomes half.
• B. the wavelength is doubled and the frequency remains the same.
• C. the wavelength and frequency both remain unchanged.
• D. the wavelength is halved but the frequency remains the same.

Answer 1

The correct option is D

the wavelength is halved but the frequency remains the same.

When an electromagnetic wave passes through a medium, the frequency remains unchanged.

Now, $c\propto \frac{1}{\sqrt{ϵ}}$

Hence, the speed of light becomes half in the medium and so wavelength is also halved.