What it is: Transfer of energy by infrared (IR) waves — part of the electromagnetic spectrum.
Key facts:
- Does NOT need particles — works through a vacuum
- This is how the Sun heats the Earth (through space)
- ALL objects emit AND absorb infrared radiation
- Hotter objects emit MORE infrared radiation
- Travels at the speed of light
Surfaces and radiation:
| Surface | Absorbs IR | Emits IR | Reflects IR |
|---|---|---|---|
| Matt black | BEST absorber | BEST emitter | Poor reflector |
| Shiny silver/white | Poor absorber | Poor emitter | BEST reflector |
Examples:
- Black car in sun — absorbs more IR → gets hotter inside
- White/silver car — reflects more IR → stays cooler
- Rescue blankets (shiny) — reflect body heat back to keep you warm
This key facts covers RADIATION — Heat Without Particles within Heat Transfer for GCSE Physics. Revise Heat Transfer in Energy for GCSE Physics with 14 exam-style questions and 11 flashcards. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 5 of 17 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Heat Transfer
Which method of thermal energy transfer occurs mainly in solids?
Explain how a convection current forms when the base of a fluid is heated.
Quick recall flashcards
Examples
wood, plastic, glass, air, wool
Fluid is heated
particles gain kinetic energy → move faster → spread out