efficiency

• Efficiency


  The fraction of the energy supplied to a device which is transferred in a useful form
• A very efficient device will waste very little of its input energy. A very inefficient device will waste most of its input energy.
• Dissipated


  The spreading out and transfer of energy stores into less useful forms, such as thermal energy causing the surroundings to heat up
• It is not possible to have an efficiency of greater than 1 or efficiency percentage of 100%. This would mean that more energy is being transferred than is being supplied, which would break the law of conservation of energy.
• Reasons devices waste energy

  • Friction between moving parts

  Electrical resistance

  Unwanted sound energy
• Devices can be made more efficient by reducing the energy that they waste or dissipate to the surroundings, e.g. using lubrication to reduce friction.