Question

For a certain electromagnetic wave in free space, at one instant the electric field vector points in the +z direction while the magnetic field vector points in the +x direction, as shown in the figure. In what direction is this wave traveling?

A. -x
B. +x
C. -z
D. +y
E. +z

Answer 1

The electromagnetic wave with the electric field pointing in the +z direction and the magnetic field pointing in the +x direction is traveling in the +y direction according to the right-hand rule. The correct option is D.

Step-by-step explanation:

The electromagnetic wave in free space with its electric field vector (E) pointing in the +z direction and magnetic field vector (B) pointing in the +x direction, by the right-hand rule, indicates that the wave is traveling in the +y direction.

According to the right-hand rule, if your thumb points in the direction of the electric field and your index finger in the direction of the magnetic field, your middle finger will point in the direction of the wave propagation.

Therefore, given the vectors E along +z and B along +x, the wave's propagation direction is mutually perpendicular to both, which is along the +y-axis.