Heat Radiation Flashcards
The ways in which heat is transferred?
Radiation, conduction or convection
What is heat radiation?
The transfer of energy by infrared radiation
How do conduction and convection transfer energy?
By particles
What is conduction?
The main form of heat transfer in solids
What is convection?
The main form of heat transfer in liquids and gases
What can infrared radiation be emitted by?
Solids, liquids and gases
Where is infrared emitted from?
The surface of an object
As it cools down, what does an object thats hotter than it’s surroundings do?
Emits more raditation than it absorbs
As it warms up, what does an object that’s cooler than its surroundings do?
Absorbs more radiation that its emits
In a given time, the hotter an object is…
The more radiation it radiated
What does radiation depend on?
The surafce colour and texture of the object
Dark, matt surfaces?
Absorb infrared radiation
Not very good emitters of infrared radiation
light shiny surfaces?
Not good absorbers
Emit infrared radiation better than dark matt surfaces
Reflect infrared
How do Solar hot water panels work?
They contain water pipes under a black surface (or painted pipes under glass)
Radiation from the Sun is absorbed by the black sufrace ro heat water in the pipes
This water can be used for washing or pumped to radiators to heat the building
