Lorentz force

When a curent flows in the wire, a force is exerted on the magnet on the top pan balance and a reading on the balance can be recorded. If the current is reversed, the balance shows a negative value, showing that the force on the magnets reverses. The force also reverses if the field direction is reversed. If a bigger current is passed through the wire the force is bigger and a larger reading is observed on the balance.

When a wire carrying an electrical current is placed in a magnetic field, each of the moving charges, which comprise the current, experiences the Lorentz force, and together they can create a macroscopic force on the wire (sometimes called the Laplace force). By combining the Lorentz force law above with the definition of electrical current, the following equation results, in the case of a straight, stationary wire: F=BIL