Electrodynamics

The Alternating Current Generator
(Alternator)

IMPORTANT POINTS

1. A Split Ring Commutator (a ring that is split) is found in a DC motor.
It changes the direction of current in the loops, ensuring that the electricity from a battery is able to produce continuous rotation of the loops.

2. A Slip Ring (has no splits in it) is found in a Alternating Current Generator.

3. What would happen if the Slip Ring in an A.C. Generator is replaced with a Split Ring?
Direct Current would be induced.

With Slip Rings the induced current is always sent to the SAME SLIP, but since loops pass opposite magnets, the current direction is changed.
With either ring, the induced current is changing direction as the passes the opposite poles of the magnets.

But SPLIT RINGS are designed to change current direction as well.
Hence there are TWO SIMULTANEOUS changes to the current direction, one caused by the opposing magnets, and the other by the splits.
Hence the CURRENT DIRECTION becomes UNCHANGED.

The current in the loops would still be alternating, but the Split Rings would be alternately connecting each loop to the other brush.
Hence the CURRENT in the EXTERNAL CIRCUIT would be in ONE DIRECTION.

Summary

Replacing the Slip Rings of an a.c. generator with a Split Ring Commutator would mean: However, since the loops are still passing through various angles with the magnetic field, the magnitude of the induced current would still be constantly changing from minimum to maximum to minimum.

4.If you are going to use alternating current to power a d.c. motor, what change should you make in the motor?
Remove the Split Ring and replace with two Slip Rings, one for each loop.

There would be no need for split rings to change the current direction since the current would already be changing its direction since it is alternating current.
The slip rings would be needed to ensure that the wires do not get tangled after one rotation.

The typical sine curve would no longer be formed. Instead the following DC graph would result, showing current flowing in ONE direction (one quadrant), but with changing magnitudes.