Electrical Terms

Electricity:
The plates or strips used in making an electric cell are called electrodes; the zinc is called the negative electrode (-), and the carbon the positive electrode (+); the current is considered to flow through the wire from the + to the-electrode. As a rule, each electrode has attached to it a binding post to which wires can be quickly fastened.

The power that causes the current is called the electromotive force, and the value of the electromotive force, generally written E.M.F., of a cell depends upon the materials used.

When the cell consists of copper, zinc, and dilute sulphuric acid, the electromotive force has a definite value which is always the same no matter what the size or shape of the cell. But the E.M.F. has a decidedly different value in a cell composed of iron, copper, and chromic acid. Each combination of material has its own specific electromotive force.