electromotive force

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The energy per unit charge that is converted reversibly from chemical, mechanical, or other forms of energy into electrical energy in a battery or dynamo.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun physics Potential energy (NOT force) divided by electric charge; measured in volts

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the rate at which energy is drawn from a source that produces a flow of electricity in a circuit; expressed in volts