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IGCSEPhysicsCambridge (CIE)Revision Notes4. Electricity & MagnetismElectrical QuantitiesElectromotive Force

Electromotive Force (Cambridge (CIE) IGCSE Physics) : Revision Note

Learn about electromotive force for your IGCSE Physics exam. This revision note includes information on how to calculate the electromotive force or emf.

Katie M

Written by: Katie M

Reviewed by: Caroline Carroll

Updated on

Electromotive force

  • Electromotive force (e.m.f.) is the name given to the potential difference of the power source in a circuit

  • It is defined as

The electrical work done by a source in moving a unit charge around a complete circuit

  • Electromotive force (e.m.f.) is measured in volts (V)

Electromotive force, IGCSE & GCSE Physics revision notes

The e.m.f. is the voltage supplied by a power supply: 12 V in the above case

Calculating electromotive force

Extended tier only

  • The definition of e.m.f. can also be expressed using the equation:

E space equals space W over Q

  • Where

    • E = electromotive force (e.m.f.), measured in volts (V)

    • W = energy transferred to the charges from the power source, measured in joules (J)

    • Q = charge moved, measured in coulombs (C)

  • This equation should be compared to the definition of potential difference as the two are closely related

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    Author
    Reviewer
    Katie M

    Author: Katie M

    Expertise: Physics Content Creator

    Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.

    Caroline Carroll

    Reviewer: Caroline Carroll

    Expertise: Physics Subject Lead

    Caroline graduated from the University of Nottingham with a degree in Chemistry and Molecular Physics. She spent several years working as an Industrial Chemist in the automotive industry before retraining to teach. Caroline has over 12 years of experience teaching GCSE and A-level chemistry and physics. She is passionate about creating high-quality resources to help students achieve their full potential.