A traveling electromagnetic wave in a vacuum has an electric field amplitude of 71.1 V/m. Calculate the intensity S of this wave. Then, determine the amount of energy U that flows through area of 0.0275 m 2 over an interval of 16.5 s, assuming that the area is perpendicular to the direction of wave propagation.

For the calculation of I = Erms2 / (cμ0), I get

I = (91.5 / √2)2 / [(2.99 x 108) (1.26 x 10-6)] = 11.07 W/m2

Intensity = 11.07 w/m^2

t = 17.1 s

A = 0.0229 m2

U = energy = IAt = (11.07) (0.0229) (17.1) J = 4.34 J

Energy = 4.34 Joules

answer: 31, 5556. 952 seconds

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.