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

Answer

A

Explanation

Frequency remains constant during refraction
`v_("med")=(1)/(sqrt(mu_(0)in_(0)xx4))=(c )/(2)(lambda_("med"))/(lambda_("air"))=(v_("med"))/(v_("air"))=(c//2)/(c)=(1)/(2)`
`therefore` wavelength is halved and frequency remains unchanged.