A flood light is covered with a fitter than transmits red light. The electric field of the emerging beam is represented a sinusolidal plane wave
`E_(x)=36 sin (1.20xx10^(7)z-3.6xx10^(15)t) V//m`
The average intensity of beam is `"watt"//("metre")^(2)` will be

Options

A. 0.86 W/`m^(2)`
B. 1.72 W/`m^(2)`
C. 3.44 W/`m^(2)`
D. 6.88 W/`m^(2)`

Answer

B

Explanation

`I_(av) = (c epsilon_(0) E_(0)^(2))/(2 ) = (3 xx 10^(8) xx 8.85 xx 10^(-12) xx 36^(2))/(2)`
= 1.72 W/`m^(2)`