Section 4 - Heat Convection Flashcards
In what states does convection of heat happen?
Convection of heat only happens in liquids and gases.
When does convection occur?
Convection occurs when the more energetic particles move from the hotter region to the cooler region, and take their heat energy with them.
Talk about convection of heat in an immersion heater.
Heat energy is transferred from the heater coils to the water by conduction.
The particles near the coils get more energy, so they start moving around faster.
This means there is more distance between them, so the water expands and becomes less dense.
This reduction in density means that hotter water tends to rise above the denser, cooler water.
As the hot water rises it dissipates (moves) the colder water out of the way, making it sink towards the heated coils.
This cold water is then heated by the coils and rises and so it goes on. You end up with convection currents going up, round and down, circulating the heat energy through the water.
When is convection most effective?
Convection is most effective in roundish or squarish containers because they allow the convection current‘s to work best.
Why does the water stay cool below the heater?
The water stays cool below the heater because the hot water rises as of the low-density so you only get convection current in the water above the heater.
What is convection currents all about?
Convection current’s are all about changes in density.
Explain convection using the radiator example.
Hotter less dense air by the radiator rises and denser cooler air flows to replace it.
