Note 14 — Chapter XIII · THE DYNAMO: BASIC PRINCIPLES

NOTE.—It should be understood that a dynamo does not generate electricity, for if it were only the quantity of electricity that is desired, it would be of no use, as the earth may be regarded as a vast reservoir of electricity. However, electricity without pressure is incapable of doing work, hence a dynamo, or so-called “generator,” is necessary to create an electromotive force by electromagnetic induction in order to cause the current to flow against the resistance of the circuit and do useful work.