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Physics vocabulary · Electricity and Magnetism

Electromotive force

Meaning in physics, with examples

nounCommon term

In physics, electromotive force means: The energy that a source such as a battery or generator gives to each coulomb of charge passing through it. Despite its name, it is not a force, and it is measured in volts.

In Turkish: elektromotor kuvvet, emk

How it is used

Usually shortened to emf, said letter by letter, with the symbol ε or E. The voltage at the terminals is less than the emf because of the source's internal resistance: V = ε − Ir. An induced emf comes from electromagnetic induction.

Example sentences

  1. The cell has an electromotive force of 1.5 V and an internal resistance of 0.5 Ω.

  2. When the coil spins faster, a larger electromotive force is induced.

Common collocations

  • emf of a cell
  • induced emf
  • internal resistance
  • terminal voltage
  • voltageThe energy transferred to or by each coulomb of charge between two points in a circuit, also called potential difference. It is measured in volts (V).
  • electromagnetic inductionThe production of a voltage, and often a current, in a conductor when the magnetic field through it changes. It is the principle behind generators and transformers.
  • resistanceHow strongly a component or material opposes the flow of electric current. It equals voltage divided by current and is measured in ohms (Ω).
  • circuitA closed path through which electric current can flow, made of a power source, wires and components such as lamps, resistors and switches.
  • electric currentThe rate at which electric charge flows past a point in a circuit. It is measured in amperes (A), and one ampere is one coulomb of charge per second.

More terms: Electricity and Magnetism

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