Page 58 - Basic Electrical Engineering

Figure 1.6 Force experienced by a conductor carrying current in a magnetic field

Figure 1.7 Force on a current-carrying conductor

Fleming’s left-hand rule

The three fingers of the left hand are stretched as shown in Fig. 1.6. If the
forefinger points towards the direction of the lines of force, and the middle

finger points toward the current flowing through the conductor, then the
thumb will point towards the direction of force experienced by the conductor.

1.9.5 A Current-carrying Coil Placed in a Magnetic Field

Now we will consider a coil placed in a magnetic field. A coil has two coil-
sides which lie in the magnetic field. These coil sides are called conductors.

Thus, a coil has two conductors. If a coil has two turns, the number of
conductors will be four. See Fig. 1.8 (a and b). In Fig. 1.8 (c) has been shown

a single turn coil placed in a magnetic field. The direction of current through
the coil has also been shown. The direction of the magnetic field is from
North pole to South pole. The direction of current in coil-side ‘a’ is upward,

i.e., towards the observer. If we apply Fleming’s left-hand rule, we find that
coil-side ‘a’ will experience an upward’ force. Similarly, by applying the

same rule, we observe that coil-side ‘á’ will experience a downward force.
The two forces acting simultaneously on the coil will develop a torque which