Thermal Radiation
Thermal radiation is heat transferred as infrared waves, which can travel through a vacuum.
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Play with the controls to see the idea in action.
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Thermal radiation is heat transferred as infrared waves, which can travel through a vacuum.
- The Sun heats Earth by radiation
- Dark matt surfaces absorb and emit most
- Shiny surfaces reflect radiation
🧠 Quick quiz
Three questions. Score 2 or more to complete the topic.
What is Thermal Radiation?
Within Physics, which covers forces, energy, waves, electricity, magnetism, light and space explained through motion and experiments, this topic explains Thermal Radiation. Physics topics explain how things move, push, heat up and carry energy, so each one here pairs a definition with a live model you can change.
Check that you can explain Thermal Radiation in your own words and give one example from everyday life. If you can do that, you have understood the core idea.
Understanding Thermal Radiation explains how the physical world behaves, from sport and transport to electricity and medicine.
Thermal Radiation in detail
Thermal radiation is the transfer of energy by infrared electromagnetic waves, which require no medium, so it can travel through a vacuum, as sunlight does. All objects emit it, and the hotter they are, the more they radiate.
Dark, matt surfaces are good absorbers and emitters, while light, shiny surfaces are poor absorbers and emitters but good reflectors. This is why vacuum flasks are silvered and why solar panels are dark. Infrared cameras detect thermal radiation to show heat loss from buildings and to find people in the dark.
How the interactive helps you understand Thermal Radiation
Watch the light rays in the interactive. Use any sliders or buttons it offers to change the values and see how the light rays responds.
Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of Thermal Radiation.
Real-life uses and examples
- Answer “explain” questions by linking Thermal Radiation to a clear cause and effect.
- Predict what a ball, car or circuit will do with Thermal Radiation before you do the calculation.
- Explain everyday devices, such as brakes, lifts or chargers, using Thermal Radiation.
Common mistakes to avoid
- Forgetting that some quantities, such as force or velocity, also have a direction.
- Mixing up Thermal Radiation with a related quantity that has different units.
- Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.
Frequently asked questions about Thermal Radiation
What is Thermal Radiation?
Thermal radiation is heat transferred as infrared waves, which can travel through a vacuum.
What are the most important points about Thermal Radiation?
The main points are: The Sun heats Earth by radiation; Dark matt surfaces absorb and emit most; Shiny surfaces reflect radiation.
Why is Thermal Radiation useful?
Understanding Thermal Radiation explains how the physical world behaves, from sport and transport to electricity and medicine.
How can I practise Thermal Radiation?
Open the interactive at the top of this page and change the controls one at a time. Predict the result before each change, then take the three-question quiz. A score of two or more marks the topic as complete on this device.
Which topics are related to Thermal Radiation?
Related topics in Physics include Waves: Basic Properties, Reflection of Waves, Interference.