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Many things rely on convection. This worksheet shows you three examples of convection in use around the home.

Use the diagrams and questions to help you to explain how convection is useful. You could:

·  make an A4 poster for each use of convection

·  copy the diagrams into a computer presentation and add labels and text to explain how convection is useful

·  make a leaflet explaining convection.

A Storage heaters

Storage heaters in the home contain bricks, which take a while to heat up and cool down. The electric heating elements are automatically switched on at night, when electricity is cheaper.

Think about the answers to these questions before you try to explain how storage heaters work.

·  Heat from inside the bricks reaches the surface of the bricks very slowly once the heat is switched off. Why does it take a long time?

·  How is the air around the bricks warmed up?

·  How does this system heat up a room?

8Ic Using convection (continued)

B Hot water systems

The diagram shows how water is heated in many homes.

If you wish, you can use these sentences to help you to explain how the hot water system works – but you wil need to put them into the correct order first!

A The water expands so its volume becomes bigger.

B Cooler water flows in to replace it.

C The header tank provides the pressure to push the hot water to the taps.

D Water is heated in the boiler.

E Heating causes the particles to gain more kinetic energy and move around at higher speeds.

F The cooler water is heated.

G After a time, a supply of hot water collects in the storage tank. The water in the tank becomes hot from the top down.

H This means that the warm water becomes less dense and rises to the storage tank.

C Hot water tanks

Hot water tanks often have two heating elements in them.

Think about the answers to these questions before you try to explain how storage heaters work.

·  Which heating element would you switch on to heat the whole tank? Why?

·  What is the advantage of having the other heating element in place? (Hint: Think about how much it costs to heat the whole tank of water.)