Question

The electric field `vec E` of an electromagnetic wave propagating in north direction is oscillating in up and down direction. Describe the direction of magnetic field `vec B` of the wave.

Answer 1

The electric field `(vec E)` and magnetic field `(vec B)` of an electromagnetic wave are always perpendicular to one another and the wave’s propagation direction. Given that the wave is travelling in the north direction and the electric field `(vec E)` oscillates up and down (which means along the vertical direction), the magnetic field `(vec B)` must be perpendicular to both. This indicates the magnetic field will be in the east-west direction.