A simple AC generator

A voltage will be induced across a conductor placed in a changing magnetic field. This can be demonstrated by making a simple AC generator. Use the 10 mm x 10 mm magnet and the 3000T coils that comes with the kit.

Objective

Measure the frequency and amplitude of the voltage induced across a solenoid coil kept near a rotating magnet. Use more than one coils to generate multi-phase AC.

Procedure

• Mount the magnet horizontally and power the DC motor from a 1.5 volts cell
• Enable A1 and A2, with analysis option
• Set timebase to 100 mS full scale
• Bring the coil near the magnet (not to touch it), watch the induced voltage
• Repeat the experiment using 2 coils.

Discussion

The voltage output is shown in figure. The phase difference between the two voltages depends on the angle between the axes of the two coils.

Bring a shorted coil near the magnet to observe the change in frequency. The shorted coil is drawing energy from the generator and the speed get reduced. The magnetic field in this generator is very weak. The resistance of the coil is very high and trying to draw any current from it will drop most of the voltage across the coil itself.