Page 60 - Basic Electrical Engineering

Figure 1.9 (a) A current-carrying coil in a magnetic field experiences a torque; (b) magnetic field
produced by the current-carrying coil and the stationary magnetic field get aligned

1.10 LAWS OF ELECTROMAGNETIC INDUCTION

Faraday, on the basis of laboratory experiments, established that whenever
there a is change in the magnetic flux linkage by a coil, EMF is induced in
the coil. The magnitude of the EMF induced is proportional to the rate of

change of flux linkages. Faraday’s laws of electromagnetic induction are
stated as:

First law: EMF is induced in a coil whenever magnetic field linking that coil
is changed.

Second law: The magnitude of the induced EMF is proportional to the rate of

change of flux linkage.

The rate of change of flux linkage is expressed as where N is the

number of turns of the coil linking the flux. Thus, the induced EMF, e is

expressed as