How do magnetic fields interact with electric currents?

Magnetic fields exert a force on moving electric charges, such as those in an electric current.

In more detail, this interaction between magnetic fields and electric currents is governed by the right-hand rule, a fundamental principle in electromagnetism. According to this rule, if you point your thumb in the direction of the current (from positive to negative) and curl your fingers, your fingers will point in the direction of the magnetic field created by the current. This is known as Ampere's circuital law.

The force that a magnetic field exerts on a moving charge is always perpendicular to the direction of motion. This force can cause the charge to move in a circular or spiral path. The magnitude of this force depends on the strength of the magnetic field, the amount of charge, and the speed at which the charge is moving. This is described by the Lorentz force law.

When a wire carrying an electric current is placed in a magnetic field, the field exerts a force on the current. This is the principle behind electric motors. In a motor, a coil of wire carrying a current is placed in a magnetic field. The field exerts a force on the current in the wire, causing the coil to rotate.

Furthermore, a changing magnetic field can induce an electric current in a conductor. This is known as electromagnetic induction and is the principle behind generators and transformers. In a generator, a coil of wire is rotated in a magnetic field, causing a change in the magnetic field through the coil. This change induces an electric current in the wire.

In summary, magnetic fields and electric currents interact in a way that allows for the conversion of electrical energy to mechanical energy and vice versa, enabling the operation of many everyday devices.