convection

Question 1

what is convection?

Answer 1

where energetic particles move away from hotter to cooler regions

Question 2

what state does convection happen in?

Answer 2

only liquids and gases

Question 3

what is a fluid?

Answer 3

a substance in which the particles are free to move around

Question 4

how does convection work?

Answer 4

• as a fluid is heated the particles gain kinetic energy and spread further apart
• causing the fluid to become less dense and so it will rise above any cooler fluid that hasn’t been heated
• as the fluid cools down it will become more dense again, and so sink back down
• if this process takes place in a limited space, like a container or a room, it can create a convection current

Question 5

how do radiators create convection currents?

Answer 5

• energy is transferred from the radiator to the nearby air particles by conduction (air particles collide with the radiator surface)
• air by the radiator becomes warmer and less dense (as particles move quicker)
• this warm air rises and is replaced by cooler air which is then heated by the radiator
• at the same time, the previously heated air transfers energy to the surroundings
• it cools, becomes denser and sinks
• cycle repeats causing a flow or air to circulate around the room

Question 6

similarities / differences between conduction and convection

Answer 6

• both involve particles gaining kinetic energy
• in conduction only energy is transferred
• in convection particles themselves move