A point source, of electromagnetic radiation has average power output of `800` W. The maximum value electric at a distance `4.0` m from the source is:

Options

A. `64.7 V//m`
B. `57.8 V//m`
C. `56.72 V//m`
D. `54.77 V//m`

Answer

d

Explanation

Intensity of electromagnetic wave is
`I=(P_(av))/(2pir^(2))=(E_(0)^(2))/(mu_(0)c)`
or `E_(0)=sqrt((mu_(0)CP_(av))/(2pir^(2)))`
`=sqrt(((4pixx10_(-7))xx(3xx10^(8))xx800)/(2pixx(4^(2))))`
`=54.77 V//m`