Heat Transfer Flashcards
What is heat
A for, of energy measured in units of joules.
What is tenperature
A measure of how hot or cold something is
Measured using a thermometer - degrees Celsius °C
The difference in temperature will decide the direction in which heat energy will move
Heat always flows from a ___ to a ___ temperature
Hot to a cold temperature
Metals are good _____
While nonmetals are better ____
Conductors
Insulators
Good conductors feel cold and good insulators always feel cold because good conductors always draw heat away from your body
Name the 3 methods of heat transfer
Conduction
Convection
radiation
Why are metals good conductors and non metals not?
Metals - free electrons enable heat transfer quickly through a metal in addition to enter atomic vibrations
Non-metals - trapped air makes it difficult for heat to Tavel via inter atomic vibrations
Explain convection?
This is concerned with the movement of heat through liquids and gasses.
Liquids - as the Bunsen heats the water at the bottom it becomes less dense and rises to the top. Cold water which is more dense ,over into take its place. This is a convection current
Gases - hot air rises and cold air which is more dense takes its place.
Exlaint heat radiation?
This is concerned with the movement of heat using electromagnetic rays, known as infra-red (I-R) rays.
I-R rays are the hottest part of the electromagnetic spectrum and they can travel through a vacuum.
All objects give out heat rays, the hotter the object the more heat is emitted.
Dark objects absorb heat well, while shiny surfaces are poor absorbers of radiant heat. Bright clothes reflect heat rays.
What is the difference between a conductor and an insulator?
A conductor allows heat to pass through it, an insulator keeps the heat from transferring through.
What particle is used to transfer heat ina conductor
Atoms
What is conduction?
The conduction of heat through solids is caused by the vibrating atoms/molecules passing the heat onto their neighbours
Why don’t conduction and convection work in space
Space is a vacuum
