CAIE IGCSE Physics Circuit Symbols and Components

Practise recognising, drawing and connecting standard circuit symbols, then predict how meters, switches, sensors, relays and output devices behave.

Exam points

recognise or draw standard symbols for supplies, meters, resistors, lamps, diodes, fuses and relays
connect an ammeter in series and a voltmeter in parallel with the component being measured
predict LDR or NTC thermistor resistance changes and their effect on current, voltage or an output device

[Maximum number: 2]

The electric starter motor in a car is switched on and off using a relay.
The relay consists of a plastic case and two flexible springy strips, X and Y, which are made of soft iron. These iron strips act as the switch when a circuit is connected between the terminals W and Z.

$Fig. 7.1 shows \(\mathrm{X$

Fig. 7.1 shows \(\mathrm{X

Fig. 7.2 shows the equipment from Fig. 7.1 inside a magnetising coil. The magnetising coil is in series with the 12 V car battery and switch S , which is open.

Fig. 7.3 shows the relay and the symbols for the car battery and the starter motor.

Fig. 7.3

The springy iron strips X and Y act as the switch for the starter motor circuit.
Complete the circuit diagram for the motor circuit.

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4.3.1.1—Circuits with cells, batteries, power question 1