Electromotive force
- When charge passes through a power supply such as a battery, it gains energy
- The electromotive force (e.m.f) is the amount of energy transferred per coulomb of charge (C) when charge passes through a power supply
- That energy drives the charge around the complete circuit and is transferred to the components
- e.m.f is measured in Volts (V)
- e.m.f is a measure of the energy transferred into the circuit by the power source
- E.m.f is also the potential difference across the cell when no current is flowing
- E.m.f can be measured by connecting a high-resistance voltmeter around the terminals of the cell in an open circuit
Measuring e.m.f in a cell
E.m.f is measured using a voltmeter connected in parallel with the cell