Power & Electricity

• alternating current

  changes direction
• direct current

  same direction
• 3 wires

  A) earth wire

  B) neutral wire

  C) live wire

  
• the live wire is brown and provides alternating potential difference
• the neutral wire is blue and completes the circuit
• the earth wire is green and yellow which is a protective wire for safety and stop it from becoming live
• energy transferred depends on power

  E = Pt
• potential difference is energy transferred per charge passed

  E = QV
• power depends on current and potential difference

  E = VI
• national grid

  giant system of cables and transformers which covers the UK and connects power stations to consumers
• the national grid uses a high potential difference and a low current
• national grid

  A) power station

  B) power lines

  C) step down transformer

  D) step up transformer

  E) consumer

  
• static electricity

  about charges that are not free to move causing them to build up in one place often ending with a spark or shock
• build up of static is caused by friction
• only electrons move in static electricity
• electric fields

  created around any electrically charged object
• charged objects in an electric field feel a force
• the closer the objects are the stronger the field
• electric charges create electric fields