Why the magnetic field is perpendicular to the electric field?

Question

I am a high school student. Recently I have read about magnetism. Each time I found magnetic field has to be perpendicular with electric field.

Is there any explanation why is it?

Answer 1

It isn't.

Consider, for example, an infinite horizontal sheet of positive charge with an infinite current-carrying wire, parallel to the sheet, suspended above it.

The electric field from the charged sheet points upward everywhere above it. The magnetic field curls around the wire. This means that, in the plane that contains the wire and is parallel to the charged sheet, the magnetic field is parallel (or antiparallel) to the electric field in this case.

Answer 2

Magnetic field arises when charged particles move with some velocity. They can be elctrons in a conductor, which is known as current. The direction of magnetic field is found out by curling your finger while keeping your thumb in the direction of or current.

For further reading, see How do moving charges produce magnetic fields?

Answer 3

In the classical description of the production of an electromagnetic wave, a charged particle is oscillating back and forth. This introduces a distortion into the preexisting radial electric field. The distortion has field components that are parallel to the direction of motion. The motion of charge also generates a magnetic field which wraps around the direction of motion. Off to the side, the magnetic field is perpendicular to the distortion, and the two of them move away from the charge at a rate which is determined by how they interact with each other.