Using Electricity: From the Wall Socket

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Using Electricity: From the Wall Socket
2011-05-16 09:08:05
Using Electricity From Wall Socket Section Physics

Using Electricity: Section 1- From the Wall Socket
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  1. What are the sources of Electricity?
    • Batteries
    • Mains
  2. What is the Power Rating of an appliance?
    The amount of energy the appliance uses each second
  3. What is Power Rating measured in?
    watts (W)
  4. What are the colours of each wire in a plug?
    • Live- Brown
    • Neutral- Blue
    • Earth- Yellow and Green
  5. What do fuses do?
    Protect flexes from overheating
  6. What happens when too large a current passes through a fuse?
    fuses are made from a thin piece of wire that will melt and break, therefore cutting off the mains supply
  7. What power ratings of an appliance use a 3A fuse?
    less than 675W
  8. What power ratings of an appliance use a 13A fuse?
    greater than 675W
  9. What fuse is used if an appliance has an electric motor?
  10. How is electrocution prevented?
    the fuse and switch are always connected to the Live wire so that the high voltage is cut off from the appliance when it is switched off or the fuse has blown
  11. What does the size of flex required depend on?
    its power rating
  12. What does the Earth Wire act as?
    A Safety Device
  13. What is double insultated?
    • appliances that have plastic casings and do not require an Earth wire since there is no risk of electrocution.
    • They only use 2-core flexes
  14. What prevents anyone who touches the casing of an appliance from getting an electric shock?
    the Earth wire is connected to the metal casing of the appliance so that, if a fault develops to the the casing "live", a large current passes and the fuse "blows".
  15. What is the symbol used to identify a double insulated appliance?
    A square inside a square
  16. What increases the risk of electrocution?
    water, it increases the ability of the human body to conduct electricity
  17. What could result in the flex overheating and a fire being started?
    if the fuse rating is too high the fuse will not "blow" when a fault develops