Components

• What do we need to know to draw circuit diagrams?

  The functions and symbols of components
• What is the purpose of a cell or battery in a circuit?

  To provide electric power to the circuit
• What does a switch do in a circuit?

  Controls the flow of electricity
• What happens when a switch is closed?

  Electricity flows through the circuit
• What is a filament lamp?

  A small bulb used in circuits
• What is the function of a fuse in a circuit?

  Breaks if too much current flows
• What does a diode do?

  Allows current to flow in one direction
• What is a light emitting diode (LED)?

  A diode that emits light when current flows
• Where are LEDs commonly used?

  In alarm clocks and traffic lights
• What is the function of an ammeter?

  Measures current in a circuit
• How is an ammeter connected in a circuit?

  In series with the circuit
• What does a voltmeter measure?

  Potential difference in a circuit
• How is a voltmeter connected in a circuit?

  In parallel with the circuit
• What are resistors used for in a circuit?

  To provide resistance to current flow
• What are the two types of basic resistors?

  Fixed and variable resistors
• What is a light dependent resistor (LDR)?

  A resistor whose resistance depends on light intensity
• How does an LDR behave in bright light?

  It has low resistance allowing high current flow
• What applications use LDRs?

  Automatic night lights and burglar alarms
• How does a thermistor function?

  Resistance changes with temperature variations
• In what applications are thermistors useful?

  In car engines and electronic thermostats
• What are the main components and their symbols in circuit diagrams?

  • Cell or battery: Provides power
  • Switch: Controls electricity flow
  • Filament lamp: Small bulb
  • Fuse: Breaks with excess current
  • Diode: Allows current in one direction
  • LED: Emits light when current flows
  • Ammeter: Measures current (in series)
  • Voltmeter: Measures potential difference (in parallel)
  • Resistors: Provide resistance (fixed or variable)
  • LDR: Resistance depends on light intensity
  • Thermistor: Resistance depends on temperature