An electromagnetic wave of frequency `v=3.0 MHz` passes from vacuum into a dielectric medium with permittivity `epsilon=4.0`. Then

Options

A. wavelength and frequency both become half.
B. wavelength is doubled and frequency remains unchanged.
C. wavelength and frequency both remain unchanged.
D. wavelength is halved and frequency remains unchanged.

Answer

D

Explanation

The frequency of electromagnetic wave remains unchanged but the wavelength of electromagnetic wave changes when it passes from one medium to another.
`c=(1)/(sqrt(mu_(0)epsilon_(0)))`
`therefore" "cprop(1)/(sqrtepsilon_(0))and vprop(1)/(sqrt(epsilon))`
`therefore" "(c)/(v)=sqrt((epsilon)/(epsilon_(0)))=sqrt((4)/(1))=2,(c)/(v)=(upsilonlambda)/(upsilonlamda')=(lambda)/(lambda')=2 or lambda'=(lambda)/(2)`