Electrical Circuit
Electricity and Magnetism

The charged particles move all together

Teaching Guidance for 11-14 Supporting Physics Teaching

All together, in every part of the circuit

Wrong Track: When the switch is closed, the charges leave the battery and move around the circuit.

Right Lines: When the switch is closed, the charged particles all around the circuit are set into motion together. When the circuit is completed, the charged particles start moving in all parts simultaneously. Those charged particles in the connecting wires, just before the bulb, move through the filament wire. Energy is shifted and the bulb comes on with no apparent delay. It is not a case of waiting for those charged particles that have just left the battery to arrive at the bulb before the bulb lights. There is a continuous and steady flow of charged particles in all parts of the complete circuit.

Encouraging thinking about movement everywhere in the loop

Thinking about the learning

The wrong tracks statement suggests the same incorrect idea from an earlier challenge that the charged particles all originate in the battery and flow out from the battery to form the electric current.

Thinking about the teaching

When talking to classes about how electric circuits work, it is natural to start with the battery, which provides the energy for the circuit and sets the charged particles in motion. However, it is important to reinforce the idea to pupils that once a circuit is completed, the charged particles start moving in all parts simultaneously.

So, rather than pointing with one finger to trace the path of the charged particles as they leave one side of the battery, it is helpful to gesture with both hands together, showing the charged particles simultaneously moving in opposite sides of the circuit loop. Don't always place one of the gesturing hands over the battery.

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