PURPOSE: To demonstrate the effect of changing the number of turns in the secondary of a transformer.

DESCRIPTION: Use the variac to put 75VAC at 60 Hz onto the primary coil of the transformer. The secondary coil is created by looping a wire around the transformer core and connecting it to the oscilloscope. The voltage produced is proportional to the number of turns in the secondary coil; the photographs above show the cases of four turns (left) and eight turns (right) in the secondary coil.

SUGGESTIONS:

REFERENCES: (PIRA 5K30.10) See also Demonstration K3-03: DEMOUNTABLE TRANSFORMER - V VERSUS N - PROJECTION METER, which is this same experiment using a projection AC voltmeter to observe the secondary voltage.

EQUIPMENT: Demountable transformer core with 250-turn primary coil, long wire with banana plugs, and oscilloscope on scope/TV cart.

SETUP TIME: 5 min.