Page 59 - Basic Electrical Engineering

will try to rotate the coil along an axis x-x′ in the clockwise direction as has
been shown in Fig. 1.8 (c). The coil will rotate by an angle of 90º. The North
pole of the magnetic field produced by the current-carrying coil will face the

stationary South pole as shown in Fig. 1.9.
The two magnetic fields get aligned as shown in Fig. 1.9 (b). If it is

possible to change the direction of current in the coil when it changes its
position from DD′ axis to XX′ axis, the coil will continue to develop torque

in the clockwise direction. We will get continuous rotation of the coil. This is
the basic principle of direct-current electric motor which will be discussed in

detail in a separate chapter.

Figure 1.8 (a) A coil having one turn; (b) a coil having two turns; (c) a single turn coil carrying
current is placed in a magnetic field; (d) the coil sides of the current-carrying coil in the magnetic field
experience force