efficiency

• Energy transfer


  Energy can be transferred from one form into another form
• Most devices aren't 100% efficient
• Efficiency


  The proportion of the energy supplied (input energy) that is actually transferred into the useful energy output
• Calculating efficiency


  1. Useful energy output / Total energy input

  2. Useful power output / Total power input
• Incandescent bulb vs LED bulb

  LED bulb is 5 times more efficient than incandescent bulb
• Efficiency can be expressed as a decimal or percentage
• Efficiency cannot be greater than 1 or 100% due to the conservation of energy principle</b>
• Calculating useful power output

  Efficiency (decimal) x Total power input
• Most devices produce some form of waste energy, often in the form of thermal energy
• Devices whose function is to produce heat are an exception, as the thermal energy is considered useful output