Physics·Thermal Physics · NSSCO 3.3.3-3.3.4
Radiation & consequences of energy transfer
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The warmth you feel from the Sun has crossed millions of kilometres of empty space to reach you — and only ONE kind of heat transfer can do that. This lesson meets radiation: heat carried by infrared electromagnetic waves that need no medium at all. We learn which surfaces give out and soak up radiation best (dull black wins, shiny silver loses), see the classic Leslie-cube experiment, and then enjoy the everyday payoff — the vacuum flask that beats all three transfers at once, solar heaters, cool houses, and the greenhouse effect that drives global warming.
What you'll learn in this lesson
By the end you should be able to (NSSCO Physics 3.3.3-3.3.4):
- Define radiation as the transfer of heat by electromagnetic waves which do not require a medium
- Identify infrared radiation as the part of the electromagnetic spectrum responsible for thermal radiation
- Describe how a surface affects radiation: dull black is the best emitter and absorber; shiny silver is the worst (but the best reflector)
- Describe experiments to show good and bad emitters and absorbers of infrared radiation (e.g. the Leslie cube)
- Identify and explain everyday applications of radiation — the vacuum flask, solar heaters and light-coloured houses
- Explain the greenhouse effect and its consequence, global warming
- Explain how conduction, convection and radiation combine in everyday situations
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