Convection Flashcards
1
Q
What is convection of heat only used in?
A
- Liquids.
- Gases.
2
Q
What is convection?
A
When the more energetic particles move from the hotter region to the cooler region and take their heat energy with them.
3
Q
What appliances use convection?
A
Immersion heaters in:
- Kettles.
- Hot water tanks.
- Convector heaters.
4
Q
Why can’t convection happen in solids?
A
Because the particles can’t move.
5
Q
What is a summary of immersion heaters?
A
- Water heats.
- Hot water is less dense.
- Less dense water rises.
- Fast-moving particles collide with slow moving particles and transfer heat.
- Water cools and becomes less dense.
- Denser water sinks again.
6
Q
How do immersion heaters work (detail)?
A
- Heat energy is transferred from the heater coils to the water by conduction (particle collision).
- The particles near the coils get more energy, so they start moving faster.
- This means there’s more distance between the particles, (the water expands and becomes less dense).
- This reduction in density means that the hotter water rises above the denser, cooler water.
- As the hot water rises it displaces the colder water, making it sink towards the heater coils.
- The cold water is then heated by the coils and rises and the process repeats.
7
Q
In immersion heaters, due to the heating process what do you end up with?
A
Convection currents, going up, around and down, circulating the heat energy through the water.
8
Q
Where is convection most efficient?
A
In roundish/squarish containers.
9
Q
What are convection currents all about?
A
Changes in density.
