Efficiency Calculations

• Efficiency = Useful energy out / Total energy in x 100
• Energy is measured in JOULES
• Efficiency = Useful power out/total power in x100
• Power is measured in watts
• Efficiency is a %
• 5000J of electrical energy are put into a motor. The motor converts this into 100J of movement energy. How efficient is it?

  Efficiency = Useful energy out/Total energy in x 100

  = 100/5000 x 100

  =2%