Heat Transfer9 Flashcards
Anything that is hot…
Gives out infrared radiation
A thermal image…
Is a picture made using infrared radiation
Infrared radiation can travel through…
Space (a vacuum) and transparent material like glass
Heat radiation is also called…
Infra red radiation
All objects…and…infra-red radiation.
Absorb
Emit
The …an object is, the …infrared radiation it emits in a given time.
Hotter
More
Cold objects?
Absorb heat radiation
Hot objects?
Emit heat radiation
Light/shiny objects?
Reflect heat well but doesn’t absorb heat well do not heat up much, emits heat slowly stay hotter for longer
Dark/dull objects?
Absorb more heat this means they heat up quickly. Hot dark objects also emit heat radiation very well this means that they cool down quickly.
How does heat travel through a solid?
By a process called conduction, caused by particles vibrating and knocking into each other.
Why are metals good conductors?
Because they contain “free electrons” which can move around the whole metal and carry the heat energy through more easily.
Why are non-metals bad conductors?
They don’t contain free electrons.
Are liquids and gases good conductors of heat?
Liquids and gases are bad conductors because the particles are too far apart to knock into each other.
Why does a metal cup feel colder than a polystyrene cup?
The metal cup will conduct heat away from your hand.