Page 62 - Basic Electrical Engineering

The direction of current flowing through the coil can be determined by
applying the right-hand-grip rule. The rule is explained as follows.

Right-hand-grip rule

Hold the coil with your right hand with the thumb opposing the direction of
movement of the magnet. The other four fingers will indicate the direction of

current flow through the coil. This means that the current induced in the coil
will produce flux in the direction of the thumb, thus opposing the flux
producing the induced EMF in the coil. See Fig. 1.10 (b).

1.11 INDUCED EMF IN A COIL ROTATING IN A MAGNETIC FIELD

Now we will consider a coil rotated in a stationary magnetic field as shown in

Fig. 1.11.
Here a coil, having two sides (conductors) is rotated in a uniform magnetic

field as shown in Fig. 1.11. Because of the rotation of the coil in the magnetic
field, flux linkage by the coil changes, i.e., the number of lines of force
passing through the coil changes. Because of change of flux linkage, EMF is

induced in the coil. The direction of the induced EMF in the conductors can
be determined by applying Fleming’s right-hand rule (FRHR).

Figure 1.11 (a) EMF is induced in a coil when rotated in a magnetic field; (b) determination of
direction of induced EMF