Electricity
Circuit diagrams, meters, series and parallel circuits, power ratings and the cost of electricity.
Before you begin
A circuit is a complete set of connections. The way components are connected determines the current, voltage and resistance.
Learning goals
- Draw and interpret circuit diagrams and components
- Set up physical circuits safely using the specified components
- Series and parallel arrangements
- Using a multimeter
- Current in series
- Potential difference in series
- Resistance in series
- Current in parallel
- Potential difference in parallel
- Resistance in parallel
- Household parallel wiring
- Appliance ratings
- Electrical power
- Cost in kilowatt-hours
- Reading an electricity bill
- Reducing electrical-energy wastage
Syllabus statements covered
- draw and interpret circuit diagrams, and set up circuits, with power sources (cell or battery), switches, lamps, resistors (fixed and variable), bells, fuses, ammeters and voltmeters
- identify series and parallel arrangements of circuit components
- use a multimeter to measure current, voltage and resistance
- state that the current is the same at every point in a series circuit
- state that the voltage across the power source is equal to the sum of voltages across the other components in a series circuit
- state that the effective resistance increases when the number of resistors connected in series increases
- state that the current through the power source is the sum of the currents in the separate branches of a parallel circuit
- state that the voltage is the same across the separate branches of a parallel circuit
- state that the effective resistance decreases when the number of resistors connected in parallel increases
- explain the advantages of connecting household appliances in parallel
- identify voltage rating and power rating found on a label of an electrical appliance
- recall and apply the relationship power = current × voltage to solve problems
- calculate the cost of using electrical appliances where the energy unit is the kWh
- identify electricity usage found on an electricity bill
- state some ways to reduce electrical energy wastage in daily lives (e.g. use energy-efficient appliances)
Lessons
Work through them in order.
- Circuit Diagrams and ArrangementsRead circuit diagrams, build simple circuits with low-voltage cells, and distinguish series from parallel connections.
- Measuring Current, Potential Difference and ResistanceUse a meter to measure current in series, and potential difference and resistance across a component.
- Series CircuitsExplain why current is the same all round a series circuit and potential differences add up to the supply.
- Parallel Circuits and Household WiringAdd branch currents at junctions and explain why every parallel branch has the full supply potential difference.
- Appliance Ratings and Electrical PowerRead an appliance's voltage and power ratings, and calculate power from current and potential difference.
- Electrical Energy, Bills and CostCalculate energy use in kilowatt-hours and its cost from meter readings, and find ways to save energy.
Practise and check
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