Electricity and Magnetism · Problem 9.9

ELECTRIC FIELDS IN MATTER — Edward Purcell & David Morin

Physics — E&M · em-waves-poynting-vector

Problem

(a) Consider the standing wave in Eq. (9.32). Draw plots of the energy density

\mathcal{U}(y,t)

\omega t

values of

0

\pi/4

\pi/2

3\pi/4

, and

\pi

. (b) Make a plot of the

y

component of the Poynting vector,

S_y(y,t)

, at

\omega t

values of

\pi/4

\pi/2

, and

3\pi/4

. Explain why these plots are consistent with how the energy sloshes back and forth between the different energy plots.