Describe the structure of the atom, limited to the position, mass and charge of protons, neutrons and electrons

Draw and use electric circuit diagrams representing them with the conventions of positive and negative terminals, and the symbols that represent cells, including batteries, switches, voltmeters, ammeters, resistors, variable resistors, lamps, motors, diodes, thermistors, LDRs and LEDs

Describe the differences between series and parallel circuits

Recall that a voltmeter is connected in parallel with a component to measure the potential difference (voltage), in volt, across it

Explain that potential difference (voltage) is the energy transferred per unit charge passed and hence that the volt is a joule per coulomb

Recall and use the equation:

energy transferred (joule, J) = charge moved (coulomb, C) × potential difference (volt, V)

\(E = Q × V\)

Recall that an ammeter is connected in series with a component to measure the current, in amp, in the component

Explain that an electric current as the rate of flow of charge and the current in metals is a flow of electrons

Recall and use the equation:

charge (coulomb, C) = current (ampere, A) × time (second, s)

\(Q = I × t\)

Describe that when a closed circuit includes a source of potential difference there will be a current in the circuit

Recall that current is conserved at a junction in a circuit

Explain how changing the resistance in a circuit changes the current and how this can be achieved using a variable resistor

Recall and use the equation:

potential difference (volt, V) = current (ampere, A) × resistance (ohm, Ω)

\(V = I × R\)

Explain why, if two resistors are in series, the net resistance is increased, whereas with two in parallel the net resistance is decreased

Calculate the currents, potential differences and resistances in series circuits

Explain the design and construction of series circuits for testing and measuring

Core Practical: Construct electrical circuits to:

a) investigate the relationship between potential difference, current and resistance for a resistor and a filament lamp
b) test series and parallel circuits using resistors and filament lamps

Explain how current varies with potential difference for the following devices and how this relates to resistance

a) filament lamps
b) diodes
c) fixed resistors

Describe how the resistance of a light-dependent resistor (LDR) varies with light intensity

Describe how the resistance of a thermistor varies with change of temperature (negative temperature coefficient thermistors only)

Explain how the design and use of circuits can be used to explore the variation of resistance in the following devices

a) filament lamps
b) diodes
c) thermistors
d) LDRs

Recall that, when there is an electric current in a resistor, there is an energy transfer which heats the resistor

Explain that electrical energy is dissipated as thermal energy in the surroundings when an electrical current does work against electrical resistance

Explain the energy transfer (in 10.22 above) as the result of collisions between electrons and the ions in the lattice

Explain ways of reducing unwanted energy transfer through low resistance wires

Describe the advantages and disadvantages of the heating effect of an electric current

Use the equation:

energy transferred (joule, J) = current (ampere, A) × potential difference (volt, V) × time (second, s)

\(E = I × V × t\)

Describe power as the energy transferred per second and recall that it is measured in watt

Recall and use the equation:power (watt, W) = energy transferred (joule, J) ÷ time taken (second, s)

\(P = \dfrac{E}{t}\)

Explain how the power transfer in any circuit device is related to the potential difference across it and the current in it

Recall and use the equations:

electrical power (watt, W) = current (ampere, A) × potential difference (volt, V)

\(P = I × V\)

electrical power (watt, W) = current squared (ampere², A²) × resistance (ohm, Ω)

\(P = I^2 × R\)

Describe how, in different domestic devices, energy is transferred from batteries and the a.c. mains to the energy of motors and heating devices

Explain the difference between direct and alternating voltage

Describe direct current (d.c.) as movement of charge in one direction only and recall that cells and batteries supply direct current (d.c.)

Describe that in alternating current (a.c.) the movement of charge changes direction

Recall that in the UK the domestic supply is a.c., at a frequency of 50 Hz and a voltage of about 230V

Explain the difference in function between the live and the neutral mains input wires

Explain the function of an earth wire and of fuses or circuit breakers in ensuring safety

Explain why switches and fuses should be connected in the live wire of a domestic circuit

Recall the potential differences between the live, neutral and earth mains wires

Explain the dangers of providing any connection between the live wire and earth

Describe, with examples, the relationship between the power ratings for domestic electrical appliances and the changes in stored energy when they are in use