Circuit Diagrams & Circuit Components (CIE IGCSE Physics)

• The diagram below shows the circuit symbols that could be used in circuit diagrams
  • You will be expected to know what each component is and how it behaves in a circuit

Power supplies

• Cells, batteries, power supplies and generators all supply current to the circuit

Resistors

• Potential dividers, fixed and variable resistors, thermistors and light-dependent resistors (LDRs) are all used to control current

Meters

• Ammeters and voltmeters are used to measure the current and potential difference
  • Ammeters are always connected in series whilst voltmeters are always connected in parallel

Electromagnetic Components

• Magnetising coils, relays and transformers use electromagnetic effects
  • Relays use a small current in one circuit to switch on a much larger current in another
  • Transformers 'step up' and 'step down' current and potential difference

Fuses

• Protect expensive components from current surges and act as a safety measure against fire

 

EXTENDED

• In addition to the above, you should be able to recognise and draw the circuit symbol for a diode:

 

A diode is a component that only allows a current in one direction

(Note: diodes are occasionally drawn with a horizontal line running through the middle of them)

 

• If a diode is connected to an a.c. (alternating current) power supply, it will only allow a current half of the time
  (This is called rectification)

A diode can be used to rectify an alternating current