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|  | Circuits |  This section describes circuits - electric "machines".
 A circuit is a loop of wire with 
its ends connected to an energy source such as a cell* or a battery*.  
 One end of the wire is connected to
the positive terminal; the other end 
of the wire is connected to the negative terminal.
The wire is connected in this way so a current* can flow through it.
 
 Having connected our circuit, we can use it to light an electric lamp, 
to run an electric motor, to heat an electric element* and so on.
 
 
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