Topic 4 - Convection

Question 1

what is the definition of convection?

Answer 1

when more energetic particles move from a hotter region to a cooler region - transferring energy as they do

Question 2

how does convection work in an immersion heater?

Answer 2

1. energy is transferred from heater coils to the thermal energy store of the water by conduction
2. particles near the coils gain energy, so move faster. this means there is more distance between them. (the water expands and becomes less dense)
3. the less dense water rises above the denser, cooler water
4. the cold water is displaced and moves towards the heater coils
5. water at the top cools and becomes more dense
6. cycle repeats

Question 3

how can you demonstrate convection?

Answer 3

1. place purple pottasium permanganate crystals in a beaker of cold water on one side
2. heat the side with the crystals with a bunsen
3. the crystals begin to dissolve into a bright purple solution
4. the purple solution is carried through the water by convection