Efficiency

• What does efficiency tell us about energy transfer?

  Fraction of energy converted to useful forms
• How do you calculate efficiency using energy transfer?

  Efficiency = useful output / total input
• What is the equation for calculating efficiency using power?

  Efficiency = useful power output / total power input
• How do you convert efficiency from decimal to percentage?

  Multiply the decimal by 100
• What happens if you calculate efficiency upside down?

  You get a value greater than 1
• Why are traditional light bulbs considered inefficient?

  Most energy is wasted as thermal energy
• How do LED bulbs compare to traditional bulbs in terms of efficiency?

  LEDs transfer more energy to light
• What are ways to increase the efficiency of energy transfer?

  • Use a pan with a wider base
  • Use a lid on the pan
  • Place heating element inside the water
  • Use materials with lower thermal conductivity
• What happens to thermal energy when using a pan to heat water?

  Some energy is wasted to the air
• Why is metal less efficient than plastic for heating?

  Metal conducts heat better than plastic
• How does a kettle improve heating efficiency?

  It reduces thermal energy loss to air