Energy transfer by heating

This lesson covers: 

  1. How energy can be transferred between objects by heating
  2. Conduction as a method of energy transfer
  3. Radiation as a method of energy transfer
  4. How insulators can slow down the rate of energy transfer

Energy can be transferred between objects by heating

When there is a temperature difference between two objects, energy will be transferred from the hotter object to the cooler object.

This transfer occurs until the objects reach thermal equilibrium - the point at which they are the same temperature.


There are two main ways in which energy can be transferred between objects by heating:

  1. Conduction
  2. Radiation

Radiation

Illustration showing radiation from the hot sun to the cold earth.

Radiation involves:

  1. All objects emit invisible waves that transfer energy - hotter objects emit more radiation.
  2. Radiation does not rely on particle contact - so objects do not need to touch.
  3. The hot object radiates more energy than it absorbs - so it cools down.
  4. The cool object absorbs radiation from the hot object - so it heats up.

Insulators and energy transfer

Illustration showing a cup with more heat transfer compared to a cup with an insulating sleeve and less heat transfer.
  • Some materials like metals easily transfer energy - these are called conductors.
  • Other materials like plastics do not transfer energy well - these are called insulators.
  • Wrapping an object in an insulator slows down energy transfer.
  • So insulators help keep hot things hot and cold things cold.