Newnes Dictionary of Electronics

E

earphone A small electro-acoustic transducer designed to fit into or onto the ear.

earth (also known as ground (US)) A low-resistance connection, intentional or accidental, to the mass of the earth or to a large conducting body serving as the earth such as a ship’s hull or the chassis of a vehicle or of electronic equipment. To make low-resistance contact with the earth a conductor, for example a system of copper wires, may be buried in the ground; this system is commonly used at radio transmitters. For low-power equipment such as receivers an earth connection may be provided either by a copper spike driven into the ground or a connection to a metal cold-water pipe.

    The potential of the earth or chassis is taken as a reference level ...