efficiency

• efficiency


  the ratio of output work to input work
• total input energy

  the total amount of energy supplied to a device
• useful energy output

  the amount of energy transferred to useful energy stores
• wasted energy output

  the amount of energy wasted or dissipated to the surroundings
• efficient device


  a device which wastes little of its input energy
• inefficient device


  a device which wastes most of its input energy
• efficiency equation


  efficiency = useful energy output/total energy input
• efficiency greater than 1 or 100%


  more energy is being transferred than supplied
• why can't you have efficiency greater than 1

  it would break the law of conservation of energy - energy would be being created
• reasons devices waste energy

  - friction between their moving parts

  - heat due to electrical resistance

  - unwanted sound or light
• ways to improve efficiency

  - lubricate mechanical devices to reduce the friction between moving parts

  
  

  - insulate heating devices to reduce the dissipation of thermal energy to the surroundings