Current Balance - EM-8607

The Current Balance measures the force on a current-carrying wire in a magnetic field:

               Force = (current)(length)(magnetic field)

In this apparatus, the current-carrying wire is perpendicular to the magnetic field. The current, wire length, and magnetic field strength can be varied.

A wire of a certain length (mounted on a circuit board) is positioned between the poles of a horseshoe magnet, resting on a mass balance. When a current runs through the wire, the force of the current on the magnet registers on the balance.

There are four different length wires (2 cm, 3 cm, 4 cm, and 5 cm), each mounted on a separate circuit board, so the relationship between wire length and magnetic force can be determined.

The magnetic field strength can be varied by removing each of the five horseshoe magnets one by one. The magnetic field remains uniform across the length of the wire because of the pole pieces in the magnet holder. The magnetic field strength can be measured with a Wireless Magnetic Field Sensor (PS-3221).

These experiments require a mass balance that will measure to 0.01 grams and a DC power supply that will supply current up to 6 amps.