Now, we know that the number of electrochemical equivalents electrolysed is proportional to the whole amount of electricity which passed through the circuit, and the product of this by the electromotive force of the battery is the work done by the latter, so that in this case also Joule showed that the heat generated was proportional to the work done.
If the current drive an electromagnetic engine, the reaction of the engine will produce an electromotive force opposing the current.
Von Jacobi showed that for a given electromotive force in the battery the horse-power is greatest when the current is reduced to one-half of what it would be if the engine were at rest.
The electromotive force of each cell is 2.14 volts, and the resistance 4.
Ohms. The Leclanche is of the ordinary type, and each cell has an electromotive force of I 64 volts and a resistance of 3 to 5 ohms (according to the size of the complete cell, of which there are three sizes in use).