energy transfers

• what is power

  the rate of energy transfer per second
• what is power dependant on

  • The voltage of a device
  • The current of a device
• what is the equation linking power, voltage and current

  P = VI
• What does voltage in an electrical device depend on?

  • Current
  • Resisitance
• what is the equation linking power, resistance and current

  P = I^2 R
• what does the energy transferred from an appliance depend on?

  • the time the appliance is switched on for
  • the power of the appliance
• how is energy transferred in an appliance?

  • As electrons pass through the power supply, energy is transferred to the electrons
  • As the electrons pass through each component, they transfer energy to each component
• What are electric motors used in?

  • AC power supplu
  • vacuum cleaners to create suction
  • washing machines to rotate the drum
• what is the equation linking energy transferred, power and time

  E = P x T
• what does the amount of energy transferred by electrical work depend on?

  • The current
  • The potential difference
  • The time the component is used for
• what is the equation linking energy transferred, charge and potential difference?

  E = Q x V
• what is the power of an appliance definition

  • The amount of energy it transfers by electrical work per second
• what does a higher power rating lead to

  • faster energy transfer
• what is the power rating of a clock

  10
• what is the power rating of a lamp

  50
• PR of a drill

  800
• PR of an iron

  1,250
• PR of a kettle

  2,400
• power rating of a hot water heater

  3,000
• power rating of an oven

  12,000
• why can't an appliance be plugged in to a supply with a very high voltage?

  • The appliance could fuse or set fire and become damaged
• what is the national grid?

  • distributes electricity across the UK via cables and transformers
• what is a step up transformer

  • increases the voltage and reduces current
• what is a step down transformer?

  • Decreases the voltage and increases the current
• what are the benefits of the national grid?

  • Efficient
  • The heating of wires and wasting of energy is reduced by