The practical electrician has to measure electrical resistance, electromotive forces, and the capacities of condensers.
The electromotive forces produced are proportional to the number of lines of force cut per second.
In the account of the experiment just given, electric currents are produced, while in Law I, electromotive forces are mentioned.
The curve of Fig. 440 represents one cycle, that is, one complete series of changes in the electromotive forces.