A plane electromagnetic wave travels in vaccum along z-direction . What can you say about the directions of its electric and magnetic field vectors ? If the frequency of the wave is 30 MHz. What is its wavelength ?

Explanation

Electric and magnetic field `barE` and B of an electromagnetic wave must be perpendicular to the propagation of electromagnetic wave. Hence they lie in X-Y plane mutually perpendicular to each other.
Frequency of wave, v=30 MHz=30xx10^(6) Hz., velocity of light, C`=3xx10^(8) ` m/s
Wavelength of the wave , `lambda=(C)/(V)=(3xx10^(8))/(30xx10^(6))=10 m`