A traveling electromagnetic wave in a vacuum has an electric field amplitude of 62.5 V/m. Calculate the intensity S of this wave. Then, determine the amount of energy? that flows through area of 0.0231 m2 over an interval of 14.9 s, assuming that the area is perpendicular to the direction of wave propagation.

a) 5.19 W/m²

b) 1.79 J

Explanation:

For the calculation of intensity, I. We have

I = E (rms) ² / (cμ), where

c = speed of light

μ = permeability of free space

I = (62.5 / √2) ² / [ (2.99 x 10^8) (1.26 x 10^-6) ]

I = 1954 / 376.74

I = 5.19 W/m²

Therefore, the intensity, I = 5.19 W/m²

t = 14.9 s

A = 0.0231 m²

Amount if energy flowing, U = IAt

U = (5.19) (0.0231) (14.9) J

U = 1.79 J