A voltage is induced in a coil swinging through a magnetic field. Faraday’s Law and Lenz’s Law are examined and the energy dissipated in a load resistor is compared to the loss of energy of the coil pendulum.

A rigid pendulum with a coil at its end swings through a horseshoe magnet. A resistive load is connected across the coil and the induced voltage is recorded using a Voltage Sensor. The angle is measured with a Rotary Motion Sensor, which also acts as a pivot for the pendulum. The induced voltage is plotted vs. time and angle. The power dissipated in the resistor is calculated from the voltage and the energy converted to thermal energy is determined by finding the area under the Power vs. Time curve. This energy is compared to the loss of energy determined from the amplitude and speed of the pendulum.

Faraday’s Law is used to estimate the magnetic field of the magnet from the maximum induced voltage. Also, the direction of the induced voltage as the coil enters and leaves the magnetic field is examined and analyzed using Lenz’s Law.

PASCO Advantage: PASCO Capstone™ calculates energy and power using the voltage and angle data. The induced voltage and the calculations are plotted in real time as the coil swings through the magnet.

Concepts

• Magnetic flux
• Faraday’s Law of Induction
• Lenz’s Law
• Conservation of energy
• Electrical power