A NEW SOURCE OF ELECTRICITY 



347 



eter needle, because there is no current in the wire. Now 

 thrust a magnet into the coil. Immediately there is a deflec- 

 tion of the needle, which indicates that a current is flow- 

 ing through the circuit. If the magnet is allowed to remain 

 at rest within the coil, the needle returns to its zero posi- 

 tion, showing that the current had ceased. Now let the 



FIG. 237. The motion of a magnet within a coil of wire produces a current of electricity. 



magnet be withdrawn from the coil ; the needle is deflected 

 as before, but the deflection is in the opposite direction, 

 showing that a current exists, but that it flows in the opposite 

 direction. We learn, therefore, that a current may be in- 

 duced in a coil by moving a magnet back and forth within 

 the coil, but that a magnet at rest within the coil has no such 

 influence. 



An electric current transforms a coil into a magnet. A 

 magnet in motion induces electricity within a coil ; that is, 

 causes a current to flow through the coil. 



