Electrical science

The maths and principles behind every circuit: units, Ohm's law, series and parallel circuits, power and energy. Work through the topics in order. Each ends with a mini test.

1. Units and prefixesThe quantities you'll use every day, their units, and how to convert mA, kW and MΩ without slipping a decimal point.6-question test
2. Ohm's lawHow voltage, current and resistance link together, the triangle that makes rearranging easy, and what changes a cable's resistance.6-question test
3. Series circuitsOne path, one current. How to add up resistance, share out the voltage, and why one break stops everything.6-question test
4. Parallel circuitsSeparate branches, same voltage. How branch currents add up and how to work out total resistance.6-question test
5. Power and energyWorking out watts three ways, turning kW and hours into kWh, and calculating what an appliance costs to run.6-question test