Bifold

• National Grid

  Power stations, cables, pylons and consumers
• Step up transformers

  To increase the voltage and decrease the current - efficiency
• Step down transformers

  To decrease the voltage and increase the current - safety
• Non renewable power stations (gas and oil) have a shorter time delay between off and on than renewable (hydroelectric)
• Power stations that do not release greenhouse gases

  • Wind farm
  • Nuclear
  • Hydroelectric
• Payback time

  The time required for the energy saving to repay the cost
• Advantages of a ring main

  • The cable can be thinner
• Base load

  The lowest amount of power that the national grid has to supply
• Why we have a National Grid

  Reliable and able to adjust to fluctuating demand
• Role of a step-up transformer

  Increase voltage, decrease current so less heat is lost
• Role of a step-down transformer

  Decrease voltage, increase current so it is more safe
• Radiation

  Transfer of heat using infrared radiation
• Types of energy transfer

  • Conduction
  • Convection
  • Radiation
• Low density

  The object has low mass in proportion to its volume
• Underfloor heating vs wall radiator

  Bigger surface area and lowest part of the room
• Earth wire

  If there was a fault the earth wire carries the current into the earth
• Fuse rating

  The maximum amount of current that can flow through a fuse
• Best absorber of heat

  Dull black
• Best reflector of heat

  White/shiny aluminium
• How convection currents form

  Liquid or gas being heated, becomes less dense, rises, then cools
• Why metals are good conductors

  The outer electrons can move freely
• Why plastics are poor conductors

  Little free electrons which are needed for conduction
• MCB

  Miniature Circuit Breaker
• Why MCBs are better than fuses

  • Can be reset, work much faster
• RCCB

  Residual Current Circuit Breaker
• Which wires RCCBs measure

  Live and Neutral
• What RCCBs protect from

  Electric shock (electrocution)
• Devices that use RCCBs

  Lawnmowers and power tools
• Main parallel circuit in homes

  Ring main
• Wires in a domestic UK circuit

  • Live
  • Earth
  • Neutral
• Purpose of the Earth wire

  Safely carry current to ground if there is a fault
• Advantages of the ring main

  • Thinner cables, Cables carry less current
• Amplitude of a wave

  The height of the wave from the middle of the wave to the top
• Frequency of a wave

  The number of waves that pass a point in a second measured in hz/hertz
• Wavelength of a wave

  The distance from the top of one wave to the top of the next wave
• Law of reflection

  Angle of incidence is equal to the angle of reflection
• Incident ray

  A ray of light which strikes a surface
• Parts of the electromagnetic spectrum used for communication

  • Radiowaves
  • Microwaves
  • Infrared
• Geostationary satellite

  A satellite that stays in the same location and rotates with the earth
• Examples of transverse waves

  • Water waves
  • Light
  • EM spectrum