Protons for Breakfast Heat Week 3

1. Protons for BreakfastHeatWeek 3 March 2014

2. In the event of an attack of giant hens… In the event of…

3. How it all fits together… Electricity Atoms Heat Electromagnetic waves

4. Tonight’s talk • Atoms and molecules are ceaselessly moving • Temperature is a measure of how fast the atoms and molecules are moving • Atoms and molecules are constantly emitting and absorbing electromagnetic waves • The frequency of the waves emitted and absorbed depends on temperature

5. Key fact to remember…

6. There are VAST numbers of atoms in everything. • In just a handful of anything there are about the same number of atoms as there are grains of sand on all the beaches and deserts on Earth combined Photo Credit: http://www.morguefile.com ID = 104101

7. Let us embark on a temperature excursion…

8. Room Temperature • Let’s start out at room temperature…

9. Brownian Motion… Web-Cam Milk Microscope Glass

10. Brownian Motion…

11. Melting Ice… Melting Ice (0 C) • And then get a little bit colder… Room Temperature (about 20 ºC) Photo credit http://www.cepolina.com/freephoto/

12. Melting Ice… Melting Ice… • What happens when an ice cube touches your hand?

13. Heat Transfer Hot Object Cold Object What happens when they come closer?

14. Heat Transfer What happens when a fast moving atom hits a slow moving atom?

15. Why did you feel cold and wet? • Water molecules in the ice speed up and escape the electrical attraction of their neighbours • Causes change of state from solid to liquid • Atoms and molecules in your hand slow down • Changes the rate at which special cells to send electrical signals to your brain - interpreted as a ‘too cold’ message

16. A short cold story… Solid Carbon Dioxide and the balloon

17. Liquid nitrogen • Getting cold… Solid CO2 (-79.2 C) Room Temperature (about 20 C) Melting Ice (about 0 C)

18. ‘Dry ice’ - Solid Carbon Dioxide • Carbon dioxide is unusual in that it transforms straight from the solid state to the gaseous state

19. ‘Dry ice’ - Solid Carbon Dioxide That’s a million million! • Stupendous numbers • Molecules travel around 500 metres per second: 1000 miles per hour • Every atom in the surface of the balloon is struck about 1012 times per second

20. Did you do your homework? • The coldest place on Earth?

21. The phases of matter… Solids, liquids and gases

22. and plasmas Solids, liquids and gases Solid Liquid Gas Solid Gas • Solids, liquids and gases are called ‘phases’ of matter… Normal melt evaporate Plasma evaporate melt sublimate Plasma Not so normal

23. A caricature of a solid

24. A caricature of a liquid

25. A caricature of a gas hitting a wall

26. A caricature of a plasma + + - - -

27. Solids, liquids, and gases

28. Liquid nitrogen • Getting cold…

29. Liquid nitrogen • Getting cold… Solid CO2 (-79.2 C) Room Temperature (about 20 C) Liquid Nitrogen (about -196 C) Melting Ice (about 0 C)

30. Another short cold story… Liquid Nitrogen and the balloon

31. Liquid nitrogen (2) • At 20 C molecules travel at around • 500 metres per second: 1000 miles per hour • At -196 C molecules travel at about half this speed: • 250 metres per second: 500 miles an hour

32. And its not just balloons The magnetic properties of terbium…

33. Magnetic Atoms Axis of orbits As many electrons orbit the atom in one sense as in another Some electron orbits are unpaired S N Magnetic Atom Representation Atom

34. The effect of temperature Low Temperature High Temperature

35. So what happens if you keep getting colder…? If the jiggling gets slower and slower then eventually atoms stop jiggling • This corresponds to the lowest conceivable temperature • Absolute zero

36. Lord Kelvin (William Thompson) • To measure is to know • If you can not measure it, you can not improve it • Heavier than air flying machines are impossible • Radio has no future • X-rays will prove to be a hoax

37. Absolute Temperaturekelvin • Used by scientists - I won’t mention it again.

38. And now let’s start getting warm • Normal body temperature for all mammals is 37 °C… Temperature ofMammals(about 37 C) Absolute Zero (-273.15 C) Solid CO2 (-79.2 C) Room Temperature (about 20 C) Liquid Nitrogen (about -196 C) Melting Ice (about 0 C)

39. The Body Temperature of Animals Photo Credit http://www.graficworld.it/public/photos/cat-dog-19.jpg

40. And warmer still… • Water boils at 100 °C… Absolute Zero (-273.15 C) Solid CO2 (-79.2 C) Temperature ofMammals(about 37 C) Room Temperature (about 20 C) Water boils 100 C Liquid Nitrogen (about -196 C) Melting Ice (about 0 C)

41. The Leidenfrost Effect • Water boils at 100 °C… • When it touches a very hot surface, it turns immediately to a vapour which causes droplets to float on a bed of vapour.

42. Break time Activity • Go forth, and be amused • Take care. Liquid Nitrogen and solid CO2 are cold and can give severe frostbite. • Balloons • Ice Cream • Thermal Camera • Hovercraft

43. Getting hotter… Much hotter…

44. And how hot is a candle flame? • Guess!

45. Gas Air Liquid Solid

46. A paperclip’s nightmare… The magnetic properties of iron…

47. The effect of temperature Low Temperature High Temperature

48. Comparing Iron and Terbium • Increasing the random motion of the iron atoms destroys the magnetically ordered state

49. Comparing Iron and Terbium Non-magnetic Magnetic Magnetic Non-magnetic • Increasing the random motion of the iron atoms destroys the magnetically ordered state • Magnetism is a ‘low’ temperature phenomenon • Even when the ‘low’ temperature is quite high! Terbium Magnetism of Terbium destroyed around -100 ºC Magnetism of Iron destroyed around 780 ºC Iron

50. Getting hotter still… • The hottest things in your house are your light bulbs! • They become white hot 2500 °C in a fraction of a second