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Protons for Breakfast Heat Week 3 March 2014 In the event of…In the event of an attack of giant hens…

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Presentation on theme: "Protons for Breakfast Heat Week 3 March 2014 In the event of…In the event of an attack of giant hens…"— Presentation transcript:

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2 Protons for Breakfast Heat Week 3 March 2014

3 In the event of…In the event of an attack of giant hens…

4 Electromagnetic waves Electricity Heat How it all fits together… Atoms

5 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

6 Key fact to remember…

7 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: ID =

8 Let us embark on a temperature excursion…

9 Room Temperature Let’s start out at room temperature…

10 Brownian Motion… Milk Microscope Glass Web-Cam

11 Brownian Motion…

12 Melting Ice… And then get a little bit colder… Photo credit Room Temperature (about 20 ºC) Melting Ice (0 C)

13 Melting Ice… What happens when an ice cube touches your hand? Melting Ice…

14 Heat Transfer Hot ObjectCold Object What happens when they come closer?

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

16 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

17 A short cold story… Solid Carbon Dioxide and the balloon

18 Liquid nitrogen Getting cold… Room Temperature (about 20  C) Melting Ice (about 0  C) Solid CO 2 (-79.2  C)

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

20 ‘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 times per second

21 Did you do your homework? The coldest place on Earth?

22 The phases of matter… Solids, liquids and gases

23 Solids, liquids and gases are called ‘phases’ of matter… SolidGasLiquid evaporate Not so normal melt evaporatemelt Normal SolidGassublimate Plasma and plasmas

24 A caricature of a solid

25 A caricature of a liquid

26 A caricature of a gas hitting a wall

27 A caricature of a plasma

28 Solids, liquids, and gases

29 Liquid nitrogen Getting cold…

30 Liquid nitrogen Getting cold… Room Temperature (about 20  C) Melting Ice (about 0  C) Solid CO 2 (-79.2  C) Liquid Nitrogen (about -196  C)

31 Another short cold story… Liquid Nitrogen and the balloon

32 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

33 And its not just balloons The magnetic properties of terbium…

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

35 The effect of temperature Low Temperature High Temperature

36 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

37 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

38 Absolute Temperature kelvin Used by scientists - I won’t mention it again.

39 And now let’s start getting warm Normal body temperature for all mammals is 37 °C… Temperature of Mammals (about 37  C) Room Temperature (about 20  C) Melting Ice (about 0  C) Solid CO 2 (-79.2  C) Liquid Nitrogen (about -196  C) Absolute Zero (  C)

40 The Body Temperature of Animals AnimalTemperature (  C ) Range (  C ) Horse38.0  0.5 Dog38.2  1.0 Cat38.5  0.7 Whale37.0  ? Rat38.5  0.5 Guinea Pig38.2  1.0 Photo Credit

41 And warmer still… Water boils at 100 °C… Temperature of Mammals (about 37  C) Room Temperature (about 20  C) Melting Ice (about 0  C) Solid CO 2 (-79.2  C) Liquid Nitrogen (about -196  C) Absolute Zero (  C) Water boils 100  C

42 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.

43 Break time Activity Go forth, and be amused Take care. Liquid Nitrogen and solid CO 2 are cold and can give severe frostbite. Balloons Ice Cream Thermal Camera Hovercraft

44 Getting hotter… Much hotter…

45 And how hot is a candle flame? Guess!

46 Solid Liquid Gas Air

47 A paperclip’s nightmare… The magnetic properties of iron…

48 The effect of temperature Low Temperature High Temperature

49 Increasing the random motion of the iron atoms destroys the magnetically ordered state Comparing Iron and Terbium

50 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! Comparing Iron and Terbium Magnetism of Terbium destroyed around -100 ºC Magnetic Non-magnetic Magnetic Non-magnetic Terbium Iron Magnetism of Iron destroyed around 780 ºC

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

52 The colour of a star depends upon its surface temperature Stars… Picture Credit:Richard Powell

53 Reminder… And how does this link to the first two weeks?

54 Lets remind ourselves about atoms (1) The internal structure of atoms Electrons ‘orbit’ around the outside of an atom very light possess a property called electric charge Nucleus occupies the centre very tiny and very heavy protons have a property called electric charge neutrons have no electric charge

55 Lets remind ourselves about atoms (2) Nuclei (+) attract electrons (-) until the atom as a whole is neutral The electrons repel each other They try to get as far away from each other as they can, a and as near to the nucleus as they can Electrons Electrons possess 1 unit of negative charge Nucleus protons possess 1 unit of positive charge neutrons have no electric charge

56 A word about frequency (1) 1 oscillation per second is called 1 hertz

57 A word about frequency… oscillations per secondis called a… 1000 (a thousand) (10 3 ) kilohertz (kHz) (a million) (10 6 ) megahertz (MHz) (a billion) (10 9 ) gigahertz (GHz) (a trillion) (10 12 ) terahertz (THz) (a million billion) (10 15 ) petahertz (PHz)

58 Microwaves From 0.8 GHz to 1000 GHz Radio & TV Infra Red Microwaves Gamma- Rays X-Rays Ultra Violet Frequency (Hertz) 1000 THz (Blue) 400 THz (Red) Electromagnetic spectrum

59 Visible light…

60 Spectra Last week we saw that different sources of light have quite different spectra Discrete (made of ‘lines’) Continuous (Like a rainbow) We make light by simply ‘hitting’ an atom: hard Strike it with an other atom Strike it with an electron ‘Shake it’ with an electric wave

61 Light from atoms… If an atom or molecule is ‘unconstrained’ then When it is hit, it ‘rings’ like a bell Atoms ‘ring’ at their natural frequency: resonance Each type of atom vibrates in a characteristic manner.

62 If an atom or molecule is ‘constrained’ then it cannot ‘ring’ clearly. The light which emerges has a mixture of all possible frequencies The balance of colours in the spectrum depends on how fast the atoms are jiggling – i.e. on temperature. Light from atoms in solids

63 Infra Red Light…

64 Radio & TV Infra Red Microwaves Gamma- Rays X-Rays Ultra Violet Frequency (Hertz) Electromagnetic spectrum 2500 °C 800 °C 20 °C

65 Infra Red Light from ‘constrained’ molecules…

66 Infra-Red light Objects at around ambient temperature emit infra-red light with a wavelength of about 0.01 mm. For example: Our bodies The Earth

67 What happens if you knock a molecule? If a molecule is hit, the atoms within a molecule vibrate. Because atoms are thousands of times heavier than electrons they ‘ring’ with a much lower frequencies. The light given off is in the infra red range of the spectrum. H20H20

68 Infra red light from unconstrained molecules Different types of molecular jiggling occur at different frequencies Water H 2 0 Carbon dioxide C0 2

69 Summary Heat Heat is the ceaseless disordered motions of atoms and molecules Temperature is a measure of the speed with which atoms and molecules move Atoms and molecules are electrical in their nature, and as they move they are constantly emitting and absorbing electromagnetic radiation

70 Electromagnetic waves Electricity Heat How it all fits together… Atoms

71 How it all fits together…

72 Homework?

73 Homework Research: Please find one fact about global warming (Write it down on a piece of paper and I’ll collect the facts at the start of the next session)

74 One minute feedback On the back of your handouts! Rip off the last sheet Please write down what is in on your mind RIGHT NOW! A question? OK A comment? OK A surprising thought in your mind? I’d love to hear it!

75 Goodnight blog.protonsforbreakfast.org This PowerPoint ™ presentation. Links to other sites & resources Me going on about things See you next week to discuss… Global Warming!


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