CP9: Electricity and circuits

• How does the radius of the nucleus compare to the whole atom?

  Over 10,000 times smaller than the atom
• What does the nucleus contain?

  Protons and neutrons
• What is the charge of protons?

  Positively charged
• What is the relative atomic mass of protons?

  One unit
• What is the charge of neutrons?

  No charge
• What is the relative atomic mass of neutrons?

  One unit
• What is the mass of electrons compared to protons or neutrons?

  Almost no mass (1/2000 of a proton)
• What are the common circuit symbols and their functions?

  • Cell/Battery: Provides potential difference
  • Switch: Turns circuit on/off
  • Fixed Resistor: Limits current flow
  • Variable Resistor: Changes resistance
  • Thermistor: Resistance changes with temperature
  • LDR: Resistance changes with light intensity
  • Motor: Converts electrical to mechanical energy
  • Diode: Allows current in one direction
  • LED: Emits light when current flows
  • Ammeter: Measures current in series
  • Voltmeter: Measures potential difference in parallel
• What does a cell or battery provide in a circuit?

  A source of potential difference
• What is the function of a fixed resistor?

  Limits the flow of current
• How does a variable resistor work?

  Changes resistance with a slider
• What happens to a thermistor's resistance as temperature increases?

  Resistance decreases
• What does an LDR's resistance depend on?

  Light intensity
• What does a motor do in a circuit?

  Converts electrical energy to mechanical energy
• What is the function of a diode?

  Allows current to flow in one direction
• What does an LED do?

  Emits light when current passes
• How is an ammeter connected in a circuit?

  In series with other components
• How is a voltmeter connected in a circuit?

  In parallel with the component
• What is the significance of negligible resistance in ammeters and voltmeters?

  It does not impact current calculations
• What are the key rules for drawing electric circuit diagrams?

  • Include an energy source
  • Ensure a closed path for current flow
  • Use correct circuit symbols for components
• What is potential difference also known as?

  Voltage
• What does potential difference measure?

  Energy transferred per unit of charge
• What is the unit of potential difference?

  Volt (V)
• How is potential difference measured?

  Using a voltmeter in parallel
• What is electric current defined as?

  Rate of flow of charge
• Why are wires in electric circuits made of metal?

  Because metal is a good conductor
• What flows in the wires of an electric circuit?

  Current, which is a flow of electrons
• What conditions are necessary for current to flow in a circuit?

  Source of potential difference and closed circuit
• What are sources of potential difference?

  Cell, batteries, electrical generator
• What is charge conservation in a closed-loop circuit?

  • Current is the same at any point
  • Number of electrons per second is constant
  • All components have the same current
• What happens to current at a junction in a circuit?

  Current flowing in equals current flowing out
• What is the flow of electrons in electrical wires?

  From negative terminal to positive terminal
• What is conventional current defined as?

  Flow of positive charge from positive to negative
• What are the two types of resistors?

  Fixed resistors and variable resistors
• How does a fixed resistor behave?

  Resistance remains constant
• How does a variable resistor change resistance?

  By changing the length of wire
• What happens to current with larger resistance?

  Smaller current flows
• What happens to current with smaller resistance?

  Larger current flows
• How does resistance behave in fixed and variable resistors?

  Stays constant or changes with current
• What happens to total resistance in series resistors?

  Total resistance equals the sum of individual resistances