Electromagnetic waves: An electromagnetic wave propagates along the +y direction as shown in the figure. If the electric field at the origin is along the +z direction, what is the direction of the magnetic field?
A) +z
B) -z
C) +y
D) +x
E) -x

Question

Electromagnetic waves: An electromagnetic wave propagates along the +y direction as shown in the figure. If the electric field at the origin is along the +z direction, what is the direction of the magnetic field? 
A) +z 
B) -z 
C) +y 
D) +x 
E) -x

Quizplus · Accepted Answer

According to the right-hand rule, the magnetic field would be in the +x direction. The direction of the electric field determines the orientation of the wave, while the magnetic field is perpendicular to both the electric field and the direction of propagation.

Electromagnetic Waves: an Electromagnetic Wave Propagates Along the +Y Direction