In one complete cycle, which field's average value is zero in the propagation of electromagnetic wave ?

Options

A. Both electric and magnetic field.
B. Only electric field.
C. Only magnetic field.
D. Only magnetic energy.

Answer

A

Explanation

For example, for electromagnetic wave propagating along + X - axis.
`E=E_(y)=E_(0)sin(omega t-kx)`
`B=B_(z)=B_(0)sin (omega t-kx)`
`rArr lt E gt = E_(0) lt sin (omega t- kx) gt = E_(0)xx 0=0`
`lt B gt = B_(0) lt sin (omega t- kx) gt = B_(0)xx 0 =0`