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2 Electricity

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  1. Electricity units

    1. Use the following units: ampere (A), coulomb (C), joule (J), ohm (Ω), second (s), volt (V) and watt (W)

  2. (b) Mains electricity

    1. Understand how the use of insulation, double insulation, earthing, fuses and circuit breakers protects the device or user in a range of domestic appliances

    2. Understand why a current in a resistor results in the electrical transfer of energy and an increase in temperature, and how this can be used in a variety of domestic contexts

    3. Know and use power = current × voltage, P = IV, and apply it to selecting appropriate fuses.

    4. Use energy transferred = current × voltage × time, E = IVt.

    5. Know the difference between mains electricity being alternating current (a.c.) and direct current (d.c.) being supplied by a cell or battery

  3. (c) Energy and voltage in circuits

    1. 2.7Series and parallel circuits

      Explain why a series or parallel circuit is more appropriate for particular applications, including domestic lighting

    2. 2.8Current in series circuits

      Understand how the current in a series circuit depends on the applied voltage and the number and nature of other components

    3. 2.9Current-voltage practical

      Describe how current varies with voltage in wires, resistors, metal filament lamps and diodes, and how to investigate this experimentally

    4. 2.10Resistance and current

      Describe the qualitative effect of changing resistance on the current in a circuit

    5. 2.11LDRs and thermistors

      Describe the qualitative variation of resistance of light-dependent resistors (LDRs) with illumination and thermistors with temperature

    6. 2.12Lamps and LEDs

      Know that lamps and LEDs can be used to indicate the presence of a current in a circuit

    7. 2.13Voltage, current and resistance

      Know and use voltage = current × resistance, V = IR.

    8. 2.14Current as charge flow

      Know that current is the rate of flow of charge

    9. 2.15Charge, current and time

      Know and use charge = current × time, Q = It.

    10. 2.16Electron flow in metals

      Know that electric current in solid metallic conductors is a flow of negatively charged electrons

    11. 2.17Current at junctions

      Understand why current is conserved at a junction in a circuit

    12. 2.18Parallel voltage

      Know that the voltage across two components connected in parallel is the same

    13. 2.19Series circuit calculations

      Calculate the currents, voltages and resistances of two resistive components connected in a series circuit

    14. 2.20Voltage and energy per charge

      Know that: • voltage is the energy transferred per unit charge passed • the volt is a joule per coulomb

    15. 2.21Energy, charge and voltage

      Know and use energy transferred = charge × voltage, E = QV.

  4. (d) Electric charge

    1. Identify common materials that are electrical conductors or insulators, including metals and plastics

    2. Practical: investigate how insulating materials can be charged by friction

    3. Explain how positive and negative electrostatic charges are produced on materials by the loss and gain of electrons

    4. Know that there are forces of attraction between unlike charges and forces of repulsion between like charges

    5. Explain electrostatic phenomena in terms of the movement of electrons

    6. Explain the potential dangers of electrostatic charges, e.g. when fuelling aircraft and tankers

    7. Explain some uses of electrostatic charges, e.g. in photocopiers and inkjet printers