(whether the pole of a permanent magnet or of an electromagnet does not matter) and if the current passes along the wire w so as to produce a south pole near the top of c slightly below N, and if the coil and core be capable of upward movement only, there will be a tendency for w and c to rise.
If a casting of soft iron or mild steel, shaped like m in fig. 2, have an insulated wire w wound round it in the manner shown, and a current passed round it in the direction of the
_0314a.jpg) Fig. 1 |
_0314b.jpg) Fig. 2 |
arrow, an electro-magnet will be produced with powerful poles, capable of strong attraction as at N and S. It will be understood that the windings are of course merely diagrammatic, many more turns of wire being used in actual practice.
If a soft iron ring, c, fig. 3, have a wire w continuously wound round it, and the current is supplied to this wire through the flexible brushes b, b1, from leads l and l1 coming from a battery of accumulators, the ring will become magnetic, and will resemble
