P1-1.5

Page 1

P1- 1.5- CONVECTON

-Convection happens when we heat a fluid (liquid or gas)

IN THE DEMONSTRATION:

-The hot gases from the burning candle go straight up above the candle

-Cold air is drawn down the other chimney to replace the air leaving the box

CONVECTION OCCURS IN HOT WATER TANKS AND DURING SEA BREEZES

How does convection work?

-Takes place in liquids and gases

-Takes place due to convection currents within the fluid

Convection currents are caused because fluids rise when they are heated because they become less dense

Then they fall as they cool as they become more dense

Convection currents transfer energy from the hotter parts to the cooler parts

Why do fluids rise when they are heated?

-Most fluids expand when they are heated because the particles move about more and take up more space

-The density decreases because the same mass of fluid now has a bigger volume

-Heating a fluid makes it rise as it becomes less dense