Which describes the magnetic field that forms when a wire carries an electric current?

Question

It is in a line perpendicular to the wire.
It is in a line parallel with the wire.
It is in a cylinder around the wire.
It is in a cylinder across the wire.

Answer 1

The magnetic field that forms when a wire carries an electric current is best described as being in a cylinder around the wire. This follows the right-hand rule, where if you grip the wire with your right hand and your thumb pointing in the direction of the current, your fingers will curl around the wire in the direction of the magnetic field lines. Therefore, the correct answer is:

It is in a cylinder around the wire.