P3.8 Components

• Cell

  
• Fixed resistor

  
• Variable resistor

  
• Thermistor

  
• Fuse

  
• Diode

  
• A is a closed switch, B is an open switch

  
• closed switch

  
• A light emitting diode will:


  Only allow current to flow in one direction and emit light when current flows through it.
• Ammeters :

  They measure current.

  They are added to a circuit in series.
• Voltmeters:

  They measure potential difference.

  They are added to a circuit in parallel.
• A resistor whose resistance decreases when temperature increases is a:


  Thermistor
• Which type of resistor allows us to easily adjust its resistance?


  Variable resistor
• A resistor which cannot vary the amount of resistance it provides is a:


  Fixed resistor
• In which type of resistor does the resistance vary with light intensity?  


  Light dependent resistor (LDR)
• The resistance of a thermistor decreases when the temperature _______.

  increases
• 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 the function of a filament lamp?

  Acts as a small bulb in the circuit
• What is the role of a fuse in a circuit?

  Breaks if too much current flows
• What is a diode's function in a circuit?

  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 do ammeters measure in a circuit?

  Current
• How are ammeters connected in a circuit?

  In series
• What do voltmeters measure in a circuit?

  Potential difference
• How are voltmeters connected in a circuit?

  In parallel
• What is the function of a resistor in a circuit?

  Provides 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?

  Has low resistance allowing high current flow
• What happens to an LDR's resistance in darkness?

  Resistance becomes very high, limiting current flow
• How can LDRs be used in automatic night lights?

  Detects light and adjusts resistance accordingly
• What is a thermistor?

  A resistor whose resistance depends on temperature
• How does temperature affect a thermistor's resistance?

  Higher temperatures lower resistance, vice versa
• Where can thermistors be used effectively?

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

  • Cell/Battery: Provides electric power
  • Switch: Controls electricity flow
  • Filament Lamp: Acts as a small bulb
  • Fuse: Breaks circuit if too much current
  • Diode: Allows current in one direction
  • LED: Emits light when current flows
  • Ammeter: Measures current (in series)
  • Voltmeter: Measures potential difference (in parallel)
  • Resistor: Provides resistance
  • LDR: Resistance depends on light intensity
  • Thermistor: Resistance depends on temperature
• What does a light emitting diode (LED) do?


  A LED will emit light when current flows through it, and only allow current to flow in one direction.
• What does an ammeter do?


  Measure the current in a circuit (or a single loop of a parallel circuit).