Efficiency

Subdecks (1)

Cards (39)

  • What happens to the energy that is not usefully transferred by the solar cells?
    Wasted
  • Suggest one advantage of the aircraft having fuel cells as well as the solar cells.
    can fly at night
  • Give one environmental advantage of using electric motors to drive the aircraft propellers rather than motors that burn a fuel.
    no greenhouse gases
  • solar cells transfer light energy to .......................................................energy.
    electrical
  • batteries transfer ............................................................. energy to electrical energy.
    chemical
  • The LEDs transfer electrical energy to ............................................................. energy.
    light
  • Turbine turns a coil in a…
    Generator
  • Give one disadvantage of using a wind generator to charge a battery.
    wind speed may be too low to operate the generator
  • State one factor, other than efficiency, that is important when considering the choice of a bulb for lighting in the home.
    availability of bulbs
  • How does the design of the stove help to improve the rate of energy transfer by infrared radiation?
    black is a good emitter of infrared radiation
    large surface area
  • Give two environmental advantages of using a wood burning stove to heat a home rather than heaters that use electricity generated from fossil fuels.
    wood is renewable
    wood is carbon neutral
  • What is meant by an energy source being renewable?

    replaced faster than it is used
  • Name two other renewable energy sources used to generate electricity.
    wind
    waves
  • The step-up transformer increases the efficiency of the National Grid. Explain how.
    decreases the current reducing energy loss
  • Suggest why it was important to confirm the efficiency independently
     
    to avoid bias
  • Outline some of the advantages of using solar cells to generate this electricity.
    conserves fossil fuel stocks
    can be used in remote areas
  • To make energy transfers more efficient, we have to maximise the useful energy and minimise the wasted energy from a transfer.
  • Equations in terms of energy
  • Energy is measured in joulesJ
  • Efficiency has no units
  • Equation in terms of power
  • Power is measured in wattsW
  • Ways to increase efficiency
    thermal insulation
    lubrication
    streamlining
  • 100% efficiency is usually impossible.
  • There is usually always some wasted heat energy in the form of heat / thermal energy.