Electricity

• What is the electricity generated by power stations called?

  Main electricity
• What type of current is main electricity?

  Alternating current
• What is the frequency of the domestic electricity supply in the UK?

  50 htz
• What does a frequency of 50 htz indicate?

  The current changes direction 50 times per second
• What are the three wires in main circuits?

  Live wire, neutral wire, Earth wire
• What does the Live Wire do?

  It carries electrical energy from the power station
• What color is the Live Wire?

  Brown
• What voltage does the Live Wire carry?

  Negative 230 volts and positive 230 volts
• What is the purpose of the neutral wire?

  It completes the circuit and is kept at 0 volts
• What color is the neutral wire?

  Blue
• What is the function of the Earth wire?

  It provides a path for current to escape safely
• What color is the Earth wire?

  Yellow-green
• What is a ring main circuit?

  • Allows multiple appliances to connect
  • Uses minimum wiring
  • Provides consistent power supply
• What type of plugs are used in the UK?

  Three pin plugs
• What do the three pins in a UK plug connect to?

  Live wire, neutral wire, Earth wire
• What is the purpose of a fuse in a plug?

  To protect against excessive current
• Where is the fuse placed in a circuit?

  At the live wire
• What happens if too much current flows through a fuse?

  The fuse overheats and melts
• What must be done after a fuse blows?

  Replace it with a new one
• What is a circuit breaker?

  A switch that opens when current is too high
• How is a circuit breaker reset?

  By pressing a reset button
• Why is the Earth wire important?

  It prevents appliances from becoming live
• What happens if an appliance has no Earth wire?

  It could cause an electric shock
• What are double insulated appliances?

  • Do not have an Earth wire
  • Made of plastic outer casing
  • Prevent current from flowing to the user
• What causes the heating effect of current?

  Resistance in wires or appliances
• What material is commonly used for wiring in houses?

  Copper
• What happens when current passes through a light bulb filament?

  It becomes hot and glows white
• What appliances use the heating effect of electricity?

  • Kettles
  • Electric ovens
  • Toasters
  • Electric fires
  • Hair dryers
• What is electrical power?

  Transferred energy per unit time
• What is the equation for electrical power?

  P = E / T
• How much energy does a 70 Watts light bulb transfer?

  70 Joules per second
• Why is a 70 Watts bulb brighter than a 50 Watts bulb?

  It transfers higher electrical energy per second
• What is the relationship between power, voltage, and current?

  P = V * I
• What is the formula for electrical energy?

  E = P * T
• How can you calculate the current needed for an appliance?

  Using P = V * I
• What are the common fuse values in plugs?

  3 amp, 5 amp, 13 amp
• What does the fuse value indicate?

  The current needed to blow the fuse
• How do you calculate the correct fuse for a 2,300 Watts appliance at 230 volts?

  Use current = power / voltage
• What is the current for a 2,300 Watts appliance at 230 volts?

  10 amp
• What is the current for a 550 Watts appliance at 230 volts?

  2.4 amp