Heat radiation Flashcards
In what 3 ways can heat energy be transferred?
- Radiation
- Conduction
- Convection
What is heat radiation?
The transfer of heat energy by infrared radiation.
How do conduction and convection transfer heat?
They involve the transfer of energy by particles.
What is the main form of heat transfer in solids?
Conduction
What is the main form of heat transfer in liquids and gases?
Convection
What can emit infrared radiation?
- Solids
- Liquids
- Gases
What can absorb and emit infrared radiation?
Any object
What increases the rate at which energy is transferred by heating?
The bigger the temperature difference between a body and its surroundings.
What does any object continually do?
Absorb and emit infrared radiation.
Where is infrared radiation emitted from?
The surface of an object.
What happens when an object is hotter than its surroundings?
It emits more radiation than it absorbs (the object cools down).
What happens when an object is cooler than its surroundings?
It absorbs more radiation than it emits (the object warms up).
What does radiation depend on?
- Surface colour
- Texture
What colour and texture is better at absorbing and emitting infrared radiation?
- Dark
- Matte
What colour and texture is worse at absorbing and emitting infrared radiation?
- Light
- Shiny
What do light and shiny surfaces do to infrared radiation?
They reflect it.
How do vacuum flasks keep heat in or out?
They have silver inner surfaces which reflect radiation.
What do solar hot water panels contain that heat water?
Water pipes under a black surface, meaning radiation is absorbed which heats the water in the pipes (used for washing or radiators).
