Lesson 1/Learning Event 1
With the two ends connected, current would only move or circulate within the loop of wire. If we
want to take current out of the loop and pass it through an external circuit, we can do it by cutting
into the loop and connecting part of a metal ring to each end of the loop. When the loop is
rotated, a potential will be placed on each part of the metal ring as shown by items 1 and 2 in the
figure. These parts of the ring are called segments. The two segments form a part called a
Now let us add two brushes to pick up and return the current to the commutator. These are items
3 and 4 in the figure, and they are kept in contact with the commutator by springs.
The circuit can now be completed between the two brushes through an external circuit for the load.
Current will continue to flow until the loop is positioned straight up and down between the
magnets. At this time, the loop will be cutting through no lines of force, so current flow stops.
During one revolution of the loop, there will be two pulses of current through the external circuit,
both in the same direction. This is called direct current because it always flows in one direction
through the load.
The current and voltage output of the generator would be very low, because there are three things
that determine a generator's output. They are the number of wires cutting the magnetic field, the
speed with which they move through the magnetic field, and the strength of the magnetic field.
An increase in any or all of these will result in an increase in generator output. Let's see what
happens when we add another loop.