A uniform plane electromagnetic wave in free space travels toward the negative…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Waves Sound and Physical Optics · Waves Sound and Physical Optics
Problem
A uniform plane electromagnetic wave in free space travels toward the negative x-direction (−^) and is incident normally on an infinite, perfectly conducting plane that lies in the yz-plane at x=0. Immediately before striking the conductor, the electric field of the incident wave oscillates along the +y-direction.
After reflection, the wave travels in the +x-direction back into the region x>0. For a perfect conductor, the tangential component of the electric field reverses sign upon reflection.
(a) For the incident wave, determine the direction of the magnetic field vector. Express your answer as a unit vector and explain your reasoning.
(b) Taking into account the stated sign change of the electric field upon reflection, determine the direction of the magnetic field in the reflected wave. Provide a clear justification based on the geometry of electromagnetic wave propagation.
(c) Compare the directions of the Poynting vectors for the incident and reflected waves. Explain how their directions are consistent with energy flow in this scenario.