Conduction, Convention & Radiation Flashcards
How is energy transferred by heating and radiation?
Energy is transferred by heating and radiation via the processes of:
Conduction
Convection
Radiation
What is the main method of energy transfer by heating in solids?
Conduction is the main method of energy transfer by heating in solids
What materials are extremely good thermal conductors and why?
Metals are extremely good thermal conductors as the delocalised electrons can collide with the atoms, helping to transfer the vibrations through the material and hence transfer heat better.
What materials are poor thermal conductors? And what are poor conductors called?
Non-metals are poor thermal conductors whilst liquids and gases are extremely poor. Poor conductors are called insulators
What material are good at insulating?
Non-metals, liquids and gases and materials containing small pockets of trapped air as air is a bad and hence a poor gonductor.
Explain why Materials containing small pockets of trapped air are especially good at insulating
Materials containing small pockets of trapped air are especially good at insulating because air is a gas and hence a poor conductor
The air is trapped, so it cannot move and form a convection current, therefore energy transfer by conduction occurs, but it happens very slowly since air is a gas
What happens when a substance is heated?
When a substance is heated, the atoms start to move around (vibrate) more
As they do so they bump into each other, transferring energy from atom to atom
What is the main way that thermal energy is transferred through liquids and gases?
Convection is the main way that thermal energy is transferred through liquids and gases
What is convection?
Convection is the main way that thermal energy is transferred through liquids and gases. Convection cannot occur in solids
What is conduction?
Conduction is the main method of energy transfer by heating in solids
Explain what happens when a fluid is heated
When a fluid (a liquid or a gas) is heated:
The molecules push each other apart, making the fluid expand
This makes the hot fluid less dense than the surroundings
The hot fluid rises, and the cooler (surrounding) fluid moves in to take its place
Eventually, the hot fluid cools, contracts and sinks back down again
The resulting motion is called a convection current
What determines the amount of infrared radiation an object/body emits?
The temperature of the body/object. The hotter object, the more infrared radiation it radiates in a given time
What affects how well an object/body emits and absorbs thermal radiation? And explain
The colour of an object affects how well it emits and absorbs thermal radiation
Black objects are the best at emitting and absorbing thermal radiation
Shiny objects are the worst at emitting and absorbing thermal radiation
Which objects are the best at emitting and absorbing thermal radiation?
Black objects are the best at emitting and absorbing thermal radiation
Which objects are the worst at emitting and absorbing thermal radiation?
Shiny objects are the worst at emitting and absorbing thermal radiation
