Electricity

• What are the definitions of current, potential difference and resistance

  • Current = Flow of electric charge around a circuit
  • Potential difference = Driving force that pushes the charge around the circuit
  • Resistance = Anything that slows the current down
• What are the 2 types of electricity supplies in the home

  • AC = alternating current -Current is constantly changing direction which is obtained by p.d where + and - end keep alternating
  • DC = direct current - current always flowing in the same direction
• what is the amount of p.d in UK mains supply

  • Ac supply
  • 230v
  • 50Hz
• what are the 3 wires in a plug? and state their uses


  • live wire = brown wire and provides an alternating p.d connected to a fuse in the plug. * If the current is too fast it will melt
  • Neutral wire = blue wire that completes the circuit and has 0v
  • Earth wire = yellow and green and acts as a safety wire to stop the appliance from becoming live.
• What are the dangers of touching a live wire?

  • It will give you an electric shock
  • Body has 0V if a live wire is touched large p.d is produced and current will flow through your body
  • which is very fatal
• What is the national grid?

  A system of transformers and cables linking power stations to consumers
• What is a step-up transformer?

  Increases voltage and decreases current
• What is a step-down transformer?

  A step-down transformer is a device that decreases the voltage of an alternating current (AC) to 230V while increasing the current. This is so it is safe to consume
• What is static electricity?

  When 2 insulators are rubbed together electrons are transferred
• What is an electric field?

  • electric field is a region in which electrically charged particles experience a force.
  • The closer to the object you are, the stronger the field is
  • The further away from the object you are, the weaker the field.
• Why does sparking occur

  Occurs when there is a large p.d between a charged object and an earthed object

  • High p.d = strong electrostatic force
  • Causes electron to jump between the gaps
• in a circuit where the ammeter and voltmeter appear

  The ammeter is in series with the circuit and the voltmeter is in parallel with circuit
• State the equation that links energy transferred, power and time

  state the equation that links energy transferred, charge flow and potential difference

  • Energy transferred = power x time
  • energy transferred = charge flow x potential difference
• State the equation that links power, potential difference and current

  state the equation that links power, current and resistance

  • power = potential difference x current
  • power = current^2 x resistance
• State the equations that link potential, current and resistance

  state the equation that links charge flows, current and time

  • potential difference = current x resistance
  • charge flow = current x time