electricity in the home

• what are the two types of electricity supplies?

  alternating current and direct current
• what happens in alternating supplies?

  the current is constantly changing direction
• how are alternating currents produced?

  by alternating voltages in which the positive and negative ends keep alternating
• what electricity supply is in uk homes?

  an alternating current supply at around 230v
• what is the frequency of the alternating current supply?

  50 cycles per second or 50Hz
• what current do cells and batteries supply?

  direct current
• what is direct current?

  a current that is always flowing in the same direction and is created by direct voltage
• what do most electrical appliances have?

  connected to the mains supply by three core cables so they have three wires inside of them each with a core of copper and a coloured plastic coating
• what does the colour of each wite show?

  it’s purpose and the colours are the same for every appliance
• what are the three wires called?

  live wire, neutral wire and earth wire
• what is the live wire?

  coloured brown - live wire provides the alternating potential difference at about 230v from the mains supply
• what is the neutral wire?

  coloured blue - neutral wire completes the circuit so when the appliance is operating normally current flows through the live and neutral wires, it is about 0v
• what is the earth wire?

  coloured green and yellow - it is for protecting the wiring and for safety as it stops the appliance casing forming becoming live and doesn’t usually carry current only when there’s a fault and is at 0v
• what voltage is your body?

  0v
• what happens if you touch a live wire?

  a large potential difference is produced across your body and a current flows through you
• what is caused when you touch a live wire?

  a large electric shock which could injure or kill you
• when is there a danger of an electric shock?

  even is a plug socket or light switch is turned of as a current isn’t flowing but there’s still a pd in the live wire
• what happens if you made contact with the live wire?

  your body would provide a link between the supply and the earth so a current would flow through you
• why is any connections between live and earth dangerous?

  if the link creates a low resistance path to earth a huge current will flow which could result in a fire