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Sensing

Potential difference, e.m.f. and energy transfer

  • 3 things to know
  • Components 01, 02 and 03

Overview

Recall questions on defining potential difference, the volt and e.m.f., the difference between e.m.f. and potential difference, energy transferred per coulomb, and why a voltmeter must have a very high resistance.

What you need to know

Answer each one before you reveal it.

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Key term

Define potential difference.

Key term

State the relationship for potential difference in terms of work and charge.

Key term

Define the volt.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Define potential difference.

    Model answer

    Potential difference is the energy transferred from the circuit per unit charge passing between two points.

  2. 2

    State the relationship for potential difference in terms of work and charge.

    Model answer

    V = W/Q, in volts when the work is in joules and the charge in coulombs.

  3. 3

    Define the volt.

    Model answer

    One volt is one joule per coulomb.

  4. 4

    Define the e.m.f. of a source.

    Model answer

    The e.m.f. is the energy transferred to the circuit by the source per unit charge passing through it.

  5. 5

    State the difference between e.m.f. and potential difference.

    Model answer

    E.m.f. is the energy given to each coulomb by the source, while potential difference is the energy given up by each coulomb in part of the circuit.

  6. 6

    Why is the symbol ε used for e.m.f. rather than E?

    Model answer

    E is already used for energy and for electric field strength, so ε is used to avoid confusion.

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