Wrap the 4-inch nail with a coil of 25 to 50 turns of the wire. Connect one end of the coil to one terminal of the knife switch. Connect the other terminal of the knife switch to the battery.

The primary side of a Tesla coil is usually a handful of turns of thick wire to handle the current without melting. This build runs at two or three amps, giving a primary power of around 150 Watts.

increasing the rate of rotation increasing the strength of the magnetic field increasing the number of turns on the coil The diagram shows four different positions of the coil in an alternator ...

In a dynamo, a split ring commutator changes the coil connections every half turn. As the induced potential difference is about to change direction, the connections are reversed. This means that ...