Question

A traveling electromagnetic wave in a vacuum has an electric field amplitude of 57.9 V/m. Calculate the intensity S of this wave. Then, determine the amount of energy U that flows through area of 0.0223 m 2 over an interval of 18.5 s, assuming that the area is perpendicular to the direction of wave propagation.

Answer 1

Intensity S = 4.446 W/m²

Amount of Energy U = 1.834 J

Step-by-step explanation:

Given that:

`E_{max` = 57.9 V/m

Area A = 0.0223 m²

Time t = 18.5 s

Then; Intensity (S) =
`((E_(max))^2)/(2 \ \mu_o \ C)`

where;

`\mu_o = 4 \pi *10 ^(-7)`

`C = 3*10^8`

∴ S =
`((57.9)^2)/(2*(4 \pi *10^(-7))*(3*10^8 ))`

S = 4.446 W/m²

Energy flow U = S*A*t

U = 4.446×0.0223×18.5

U = 1.834 J