Magnetism and magnetic fields Study Guide

When an electric current flows through a conductor placed within a magnetic field, the conductor experiences a force. This phenomenon is known as the motor effect. The force arises because the magnetic field produced by the current interacts with the external magnetic field. The strength of this force depends on several factors: the strength of the magnetic field, the magnitude of the current, and the length of the conductor that is actually within the magnetic field. For a conductor placed at right angles to the magnetic field, the force acting on it can be calculated using the formula F = BIL.

Here, F represents the force on the conductor, measured in Newtons (N). B is the magnetic flux density, which quantifies the strength of the magnetic field, measured in Tesla (T). I is the current flowing through the conductor, measured in Amperes (A). L is the length of the conductor within the magnetic field, measured in metres (m).

It is crucial that the conductor is perpendicular to the magnetic field lines for this simplified equation to be directly applicable. If the conductor is parallel to the magnetic field lines, no force is experienced. At other angles, a force is still produced, but it is a fraction of the maximum force and the calculation becomes more complex. This formula is fundamental to understanding how electric motors work, as it explains the force that causes rotation. For accurate calculations, ensure all units are in their standard SI forms (metres, Amperes, Tesla) to obtain the force in Newtons.