Fig. 9.97. In the next place, the current is able, not merely to deflect a magnet, but also to render soft iron magnetic. Let us take, for instance, the wire connected with the one pole of the battery, and cover it with thread, in order to insulate it, and let us wrap this wire round a cylinder of soft iron, as in Fig. 9. If we now make a communication between the other extremity of the wire, and the other pole of the battery, so as to make the current pass, it will be found that our cylinder of soft iron has become a powerful magnet, and that if an iron keeper be attached to it as in the figure, the keeper will be able to sustain a very great weight.
Its Heating Effect.
98. The electric current has likewise the property of heating a wire through which it passes. To prove this, let us connect the two poles of a battery by means of a fine platinum wire, when it will be found that the wire will, in a few seconds, become heated to redness. In point of fact, the current will heat a thick wire, but not so much as a thin one, for we may suppose it to rush with great violence through the limited section of the thin wire, producing in its passage great heat.
