1. Today’s lesson Heat transfer If you’re waiting you can finish your “convection” mind map

2. Heat transfer

3. Heat can travel by Convection A hot fluid expands, so is less dense, so rises. Cold fluid takes its place. A convection current can be formed.

4. Examples of Convection

5. Heat cannot travel in solids by convection. Why ?

6. Heat can also travel by Conduction

7. Gather round Mr Porter

8. Heat can travel by Conduction Hot particles vibrate more, so bump into adjacent particles.

9. Heat can travel by Conduction Metals are good conductors of heat Why ?

10. Heat can travel by Conduction Most gases are poor conductors of heat (insulators) Why ?

11. There’s one other way! ¡Uno mas!

12. Can you quickly, quietly and sensibly follow Mr Porter

13. Heat transfer by infrared radiation This is an invisible form of light It can travel through a vacuum Heat from the sun reaches us through space by infrared radiation

14. Infrared radiation Mmmm. Nice and warm

15. Infrared images

16. Let’s experiment! Yes!

17. Time (mins)Temp of black tin/°C Temp of shiny tin/°C 0 1 2 3 4 5 6 7 8 9 10

18. Infrared radiation Black objects are good absorbers of infrared radiation.

19. Infrared radiation Shiny objects reflect infrared radiation. Nottingham Forest winning the champions league in 1979