Alternating Current Power Systems 139
tor can be moved through the magnetic field, or the conductor can be held
stationary and the magnetic field can be moved past it. Thus, current will
be induced as long as there is relative motion between the conductor and
magnetic field.
If the conductor shown in Figure 6-1 is moved upward, the needle
of the meter will move to the right. However, if the conductor is moved
downward, the needle of the meter will deflect to the left. This shows that
the direction of movement of the conductor within the magnetic field
determines the direction of current flow. In one case, the current flows
through the conductor from the front of the illustration to the back. In
the other situation, the current travels from the back to the front. The di-
rection of current flow is indicated by the direction of the meter deflec-
tion. The principle demonstrated here is the basis for electrical power
generation.
In order for an induced current to be developed, the conductor must
have a complete path or closed circuit. The meter in Figure 6-1 was con-
nected to the conductor to make a complete current path. If there is no
closed circuit, electromagnetic induction cannot take place. It is impor-
tant to remember that an induced current causes an induced electromotive
force (voltage) across the ends of the conductor.Figure 6-1. Electromagnetic induction