Plate, Negative. The plate in a battery, such as carbon, copper or platinum, which is not attacked by the solution. Plating, Electro-. The method of coating one metal with another by electrolysis. Polarity. The peculiarity, in a body, of arranging itself with reference to magnetic influence. Parallel. When a number of cells are coupled so that their similar poles are grouped together. That is to say, as the carbon plates, for instance, are connected with one terminal, and all the zinc plates with the other terminal. Polarization. When the cell is deprived of its electro-motive force, or any part of it, polarization is the result. It is usually caused by coating of the plates. Porosity. Having small interstices or holes. Positive Current. One which deflects a needle to the left. Positive Any current flowing from the active element, Electricity. such as zinc, in a battery. The negative electricity flows from the carbon to the zinc. Potential, Electric. The power which performs work in a circuit. Potential Energy. That form of force, which, when liberated, does or performs work. Power Unit. The volt-amperes or watt. Primary. The induction coil in induction machines, or in a transformer. Push Button. A thumb piece which serves as a switch to close a circuit while being pressed inwardly. Quantity. Such arrangement of electrical connections which give off the largest amount of current. Receiver. An instrument in telephony and telegraphy which receives or takes in the sound or impulses. Relay. The device which opens or closes a circuit so as to admit a new current which is sent to a more distant point. Repulsion, That tendency in bodies to repel each other when Electric. similarly charged. Resilience. The springing back to its former condition or position. Electricity has resilience. Resistance. The quality in all conductors to oppose the passage of a current. Resistance Coil. A coil made up of wire which prevents the passage of a current to a greater or less degree. Resistance, The counter force in an electrolyte which seeks Electrolytic. to prevent a decomposing current to pass through it. Resistance: Internal, The opposing force to the movement of a current External. which is in the cell or generator. This is called the _internal_. That opposite action outside of the cell or generator is the _external_.