Thermal Energy & Conduction
Science: KS3, topic 3.2.28
Thermal energy
The movement of thermal energy (heat) occurs when there is a difference in temperature. This transfer of energy can occur through one of three methods.
Movement of thermal energy
- Thermal energy (heat) occurs when there is a difference in temperature
- It moves through one of three processes – either conduction, convection, or radiation
- Remember heat does not move up. Heat can flow in any direction as long as it is from a hotter temperature to a colder temperature.
- Hot air flows upwards
Heat vs temperature
- Heat measures how much thermal energy an object has and is measured in Joules
- Temperature is a measurement of how hot something is and is measured in °C
Conduction
- Conduction occurs in solids. A conductor allows thermal energy to be transferred easily.
- A material which does not allow thermal energy to be transferred easily is called an insulator.
- Metals are normally very good conductors. Air is a poor conductor (insulator).
Conduction in practice
- You might have experienced conduction when you have held a snowball in your hand.
- Your hand conducts energy to the snowball and so it melts.
- Another example is leaving a metal poker in a fire, eventually it becomes too hot to touch. Or when your feet get hot when walking on the sand on a tropical beach.
Exploring conduction
- You can see conduction in action if you attach pins to a retort stand with wax and heat one end. Eventually, the wax will melt and the pins will drop.
- You can investigate which metal (independent variable) will conduct heat the fastest with this method. In some cases the metal may even melt before the wax!
Conduction in the real world
- Have you ever left a spoon in the cup you make a cup of tea? And the spoon heats up?
- The spoon is made of metal
- The metal is made up of atoms (or ions) but are able to vibrate
- The boiling hot water transfers thermal energy from the boiling water to the colder metal spoon
- The atoms gain energy and so start to vibrate faster
- These vibrations are transferred to its neighbouring atoms
- Eventually the tip of the spoon will become hot to the touch
Test yourself on Thermal Energy & Conduction
When does heat occur?