Basic Current Balance

A current-carrying wire in a magnetic field experiences a counter-intuitive force that is transverse to both the wire and to the direction of the magnetic field. With the Basic Current Balance, students can perform quantitative investigations into the interaction between a current-carrying wire and a magnetic field. Vary the wire length, the current, and the magnetic field, and then measure the resulting force.

Add the Current Balance Accessory Kit, and students can also determine how the angle between the wire and the magnetic field affects the force. With this addition, all the relevant variables can be analyzed.

How It Works

One to six magnets are mounted on an iron yoke, which is placed on a gram balance. A conductor is suspended between the magnets. The weight of the magnets and yoke is measured, then a current (0-5 A) is passed through the conductor. The change in the reading of the balance (0-4 grams) measures the force between the conductor and the magnetic field.

Six conductors of different lengths are provided and can be easily changed while maintaining a repeatable position with respect to the magnetic field. The magnetic field is proportional to the number of magnets used.

Typical Experiments

• Force versus Current
• Force versus Length of Wire
• Force versus Magnetic Field
• Force versus Angle (Current Balance Accessory Kit needed)

Special Features

• Measure Force vs. Current, Wire Length, Magnetic Field and Angle
• Use a Gram Balance to Measure Force