
2 Electric Motors and Drives
PRODUCING ROTATION
Nearly all motors exploit the force which is exerted on a
current-carrying conductor placed in a magnetic field. The
force can be demonstrated by placing a bar magnet near a
wire carrying current, but anyone who tries the experiment
will probably be disappointed to discover how feeble the
force is, and will doubtless be left wondering how such an
unpromising effect can be used to make effective motors.
We shall see that in order to make the most of the mechan-
ism, we need to arrange for there to be a very strong magnetic
field, and for it to interact with many conductors, each carry-
ing as muc ...