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

Options

A. wave length is halved and ferquency remains unchanged
B. wave length is doubled and frequency becomes half
C. wave length is doubled and the frequency remains unchanged
D. wave length and frequency both remain unchanged.

Answer

A

Explanation

Frequency remains constant during refraction
`v_(med)=(1)/(sqrt(mu_0epsi_0xx4))=(c)/(2)`
`(lamda_(med))/(lamda_(air))=(v_(med))/(v_(air))=(c)/(2)=(1)/(2)`
wavelength is halved and frequency remains unchanged