A-B-C of Electricity

by Wm. H. Meadowcroft

STEEL PERMANENT MAGNET———— IRON————
Fig. 27

Although a motor is made like a dynamo, we will show a different form of machine from the dynamo already illustrated, because it will help you to understand more easily. (Fig. 28.)

Here we have an electromagnet with its poles, and an iron armature wound with wire, just as in the dynamo we have described, except that its form is different.

Fig. 28

A commutator and brushes are also used, but the electricity, instead of being taken away from the brushes, is taken to them by the wires connected with them. Two wires are also connected which take part of the electricity around the magnet, just as in the dynamo.

Now, when the volts pressure and ampères of electricity coming from a dynamo or battery are turned into the wires leading to the brushes of the motor, they go through the commutator into the armature and round the magnet, and so create the lines of force at the poles and magnetize the iron of the armature.

Let us see what the effect of this is.

The poles of the magnet become north and south, and the four ends on the armature also become north and south, two of each.