Evaporation, Boiling, Freezing: A Dramatic Adventure 
Evaporation, Boiling, Freezing: A Dramatic Adventure
by Prof. Miller
Video Lecture 25 of 46
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Date Added: February 5, 2015

Lecture Description

Some very strange things are here encountered. Indeed - some of it borders on witchcraft! But this is how NATURE behaves - in strange and wonderful ways!

A. We boil some water in a flask. We drive out all the occluded
gases and air. We stopper the flask. We take away the heat
source. The water STOPS boiling. Now we put our hands on
the flask. Mirabile dictu: the water begins to boil again —
with NO heat being added. Indeed - what we are doing is
TAKING HEAT ENERGY AWAY! The mechanism? The hands
are cold for the flask. Some of the water vapour condenses. The
pressure in the flask is reduced. The water can boil at lower pressure at a lower temperature. Strange indeed! And we can continue this operation for all of an hour. Try it - you will be enchanted.

B. If this is all true then we can do an astonishing thing. We can reduce the pressure above some water under a bell-jar. The water
can boil at lower and lower pressure and thus at lower and lower
temperature AND - mark this: it can boil at so low a temperature that it freezes! Hard to believe. This scheme of things
is known as THE TRIPPLE POINT since the water is in three phases:
liquid - solid - vapour. It is as dramatic an adventure as one
can see.

C. And here is an adventure for the dining table: Some ice resides
in a glass of ice water. We supply the guest with a short piece of
string. PROBLEM: get out some ice using the string. HOW? Lay
the string on the ice - gently - pour on some table salt. Wait
a bit. The salt melts some ice - the water which results freezes
again. The string is fixed to the ice. Strange business!

D. And all the while we are doing these wonderful things we can re¬
turn to the flask of water and BOIL IT AGAIN by laying on the
hands!

Course Index

  1. The Idea of the Center of Gravity
  2. Newton's First Law of Motion: Inertia
  3. Newton's Second Law of Motion: The Elevator Problem
  4. Newton's Third Law of Motion: Momentum
  5. Energy and Momentum
  6. Concerning Falling Bodies & Projectiles
  7. The Simple Pendulum and Other Oscillating Things
  8. Adventures with Bernoulli: Bernoulli's Principle
  9. Soap Bubbles and Soap Films
  10. Atmospheric Pressure
  11. Centrifugal Force and Other Strange Matters
  12. The Strange Behavior of Rolling Things
  13. Archimedes' Principle
  14. Pascal's Principle: The Properties of Liquids
  15. Levers, Inclines Planes, Geared-wheels and Other Machines
  16. The Ideas of Heat and Temperature
  17. Thermometric Properties and Processes
  18. How to Produce Heat Energy
  19. Thermal Expansion of Stuff: Solids
  20. Thermal Expansion of Stuff: Gases & Liquids
  21. The Strange Thermal Behavior of Ice and Water
  22. Heat Energy Transfer by Conduction
  23. Heat Energy Transfer by Convection
  24. Heat Energy Transfer by Radiation
  25. Evaporation, Boiling, Freezing: A Dramatic Adventure
  26. Miscellaneous Adventures in Heat
  27. The Drama in Real Cold Stuff: Liquid Nitrogen
  28. The Physics of Toys: Mechanical
  29. The Physics of Toys: Acoustic and Thermal
  30. Waves: Kinds of Properties
  31. Sound Waves: Sources of Sound & Pitch and Frequency
  32. Vibrating Bars and Strings: The Phenomenon of Beats
  33. Resonance: Forced Vibrations
  34. Sounding Pipes
  35. Vibrating Rods and Plates
  36. Miscellaneous Adventures in Sound
  37. Electrostatic Phenomena: Foundations of Electricity
  38. Electrostatic Toys, Part 1
  39. Electrostatic Toys, Part 2
  40. Adventures with Electric Charges
  41. Adventures in Magnetism
  42. Ways to "Produce" Electricity
  43. Properties and Effects of Electric Currents
  44. Adventures in Electromagnetism
  45. Further Adventures in Electromagnetism
  46. Miscellaneous and Wondrous Things in E&M

Course Description

Demonstrations in Physics was an educational science series produced in Australia by ABC Television in 1969. The series was hosted by American scientist Julius Sumner Miller, who demonstrated experiments involving various disciplines in the world of physics. The series was also released in the United States under the title Science Demonstrations.

This program was a series of 45 shows (approximately 15 minutes each) on various topics in physics, organized into 3 units: Mechanics; Heat and Temperature / Toys; and Waves and Sound / Electricity and Magnetism.

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