1. HEAT ENERGY AND ITS TRANSFER

2. 2. HEAT TRANSFER BY CONVECTION

3. Learning Points 1.State that heat flows through liquids by convection currents. 2.Explain convection currents in terms of density. 3.Give examples of everyday uses of convection currents.

4. Convection Convection takes place in liquids and gases. Convection will not take place in solids because the particles are too close together and can only move a little bit.

5. Convection When substances are heated, the particles vibrate more vigorously, and as a result, spread out more. Because the particles are not so tightly packed anymore, the heated substance becomes slightly less dense and therefore lighter. The less dense liquid or gas will now rise and the cooler liquid or gas will move in and take its place.

6. Convection experiment 1.Place about 400mls of water into a beaker and place on a tripod stand. 2. Start to heat the water with a bunsen burner (blue flame). 3. Carefully drop the coloured crystal into the beaker so that it is seating at the bottom of the beaker. Watch what happens. www.abernet.org.uk

7. Convection experiment Complete the diagram to show what happened.

8. As a result of these movements, a convection current will be set up in the substance. The less dense liquid will now rise and the cooler liquid or will move in and take its place. Convection experiment Explanation website.lineone.net

9. Convection experiment http://esthermei- physicsproject2009.blogspot.com/ Click here to visit a website and see a video of the same experiment.experiment

10. Convection currents can be found when liquids are heated for cooking. Convection currents in liquids drinkmatron.com