Mains electricity

• Mains electricity


  • Difference of about 230V
  • Frequency of 50Hz (50 times per second)
• Mains electricity current


  Moves back and forth 50 times per second
• Wires in mains electricity circuit

  • Live
  • Neutral
  • Earth
• Live


  Brown
• Neutral


  Blue
• Earth


  Green and yellow stripes
• DC electricity is often used in batteries and electronic devices due to its ability to provide a constant and steady current.
• AC electricity is commonly used in homes and businesses because it can be easily converted to different voltages using transformers.
• The current is the rate at which charge flows through a conductor.
• The current flowing through the resistor is directly proportional to the potential difference across it.
• AC (alternating current) electricity periodically changes direction, while DC (direct current) electricity flows in one direction only.
• Current can be measured using an ammeter, which has low resistance to avoid affecting the circuit's flow of electrons.
• Ohm's law states that if the resistance remains constant, then the current will be directly proportional to the potential difference (V = IR).
• Ammeter readings are usually given in Amperes (Amps).
• Fuses


  the three pin plug also has a fuse
• Fuse function

  Melts if the current gets too high, which breaks the circuit
• Fuses


  prevent fires
• Fuse ratings


  • 3A
  • 5A
  • 13A
• Fuse rating


  Tells you what current causes the fuse to melt
• Circuit breakers

  do the same job as Fuses but are electromagnetic switches that can be reset easily
• Circuit breakers


  • Take less time to react than fuses take to blow
• Short Circuits


  If a live wire inside the appliance touches the metal casing, a very big current passes. This causes the fuse to blow, which cuts the current off.
• Earthing


  Connecting appliances with metal cases to the earth to provide a safe path for current in the event of a fault
• Earthed appliances with metal cases

  • Usually earthed
  • If a fault occurs, a large current flows from the live wire to earth
  • This melts the fuse and disconnects the live wire
• Double insulation

  Appliances made of plastic are already insulated so don't need an earth wire
• Double insulated appliance


  Appliance that is insulated and does not need an earth wire
• Sockets

  • Made of plastic and contain the wires
  • Insulator
• Earth wire

  The longest plug makes contact with the earth wire of a wall socket.
• Earthed

  Appliances with metal cases will be automatically earthed
• Plugs

  • 3 Pins that stick out of the case
  • Pins are made of brass because it's a good conductor and won't rust or bend easily
  • The case is made of plastic because it's an insulator and is shaped so that the wires can't touch each other
• Resistance: A measure of how difficult it is for electric charges to move around a circuit.
• Cables

  • Made of 2-3 insulated copper wires
  • Surrounded by an outer layer of rubber
• Copper

  • Good conductor
  • Bends easily
• Thicker cables

  • Used for different things
  • The thicker the wire, the more current needs to pass through
• Plastic


  • Good insulator
  • Stops people from getting electric shocks if they touch it
• Resistance heating


  Heating due to resistance
• When a current passes through a resistor

  the power supplied to the resistor heats the resistor
• Power


  current^2 x resistance
• Current


  Flow of electric charge
• Heat transfer

  Transfer of thermal energy