A point source of electromagnetic rediation has an average power output of 960 W. The peak value of the electric field at a distance 400 cm from the source is

Options

A. `60 Vm^(-1)`
B. `120 Vm^(-1)`
C. `30 Vm^(-1)`
D. `180 Vm^(-1)`

Answer

A

Explanation

Given average power output .
P = 960 W
Distance r =400 cm = 4 cm
intensity of EM waves is given by
`I= (P )/( 4pi r^(2)) = (1)/( 2 ) epsilon_(0) E_(0)^(2) rArr = (p )/( 2pi r^(2) epsilon_(0) c)`
`sqrt((960)/(2xx 3l 4xx 4^(2) xx 8.85 xx 10^(-12) xx 3xx 10^(8)))`
`= sqrt( 0.36 xx 10^(4) ) = 0.6 xx 10^(2) =60 Vm^(-1)`