KS2 SATs Science: Electricity Guide

Simple circuits

A circuit needs a complete, unbroken loop for electricity to flow, including a power source (like a battery), wires and a component such as a bulb or buzzer.

Conductors and insulators

A conductor allows electricity to pass through it easily — most metals are good conductors. An insulator does not allow electricity to pass through easily, such as plastic and rubber, which is why wires are covered in plastic.

Circuit diagrams

Circuit diagrams use standard symbols for components: a circle with a cross for a bulb, two parallel lines of different lengths for a battery, and a break in the line for a switch.

Changing brightness and volume

Adding more cells (batteries) usually makes a bulb brighter or a buzzer louder. Adding more bulbs in the same simple circuit usually makes each one dimmer, as the power is shared between them.

Common mistakes

• Drawing a circuit diagram with a gap, forgetting the loop must be complete.
• Mixing up the symbols for a bulb and a buzzer.
• Assuming more bulbs always means brighter — in a simple series circuit, it's the opposite.