Efficiency

• What can energy be transferred into?

  Different forms of energy
• Why are most devices not 100% efficient?

  Because energy is lost in the process
• What is efficiency in terms of energy output?

  • Proportion of input energy converted to useful output
  • Useful energy output vs. total energy input
• What type of energy does a lamp primarily output?

  Light energy
• How is heat energy classified in a lamp's output?

  As waste energy or non-useful energy
• What is the formula for calculating efficiency?

  Efficiency = useful energy output / total energy input
• How can efficiency be calculated using power?

  Efficiency = useful power output / total power input
• If a lamp has an input of 300 joules and outputs 45 joules of light, what is its efficiency?

  0.15
• What is the efficiency of an LED lamp that outputs 225 joules from 300 joules input?

  0.75
• How many times more efficient is the LED lamp compared to the incandescent bulb?

  5 times more efficient
• How do you convert efficiency from decimal to percentage?

  Multiply by 100
• What happens if you calculate efficiency incorrectly?

  You may get a value over 1 or 100%
• What does an efficiency rating of 133% imply?

  More energy output than input
• What principle explains why energy cannot be created or destroyed?

  The conservation of energy principle
• If a microwave has a total power input of 800 watts and is 70% efficient, what is the useful power output?

  560 watts
• What is the relationship between waste energy and efficiency?

  • No device is 100% efficient
  • Waste energy is often thermal energy
  • Some devices intentionally produce waste energy as useful output
• What is an exception to the rule of efficiency in devices?

  Devices that produce heat as their function
• How does an electric heater's waste energy differ from other devices?

  It counts as useful output