Miscellaneous Adventures in Sound 
Miscellaneous Adventures in Sound
by Prof. Miller
Video Lecture 36 of 46
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Date Added: February 5, 2015

Lecture Description

A - Since oscillating systems have intimate connection with the production of SOUND we show here a very pretty thing - THE BLACKBURN PENDULUM. A rigid support has two strings fixed to it which join a third to constitute a pendulum of interesting complexion. A funnel hangs as a pendulum bob. We put salt or sand or sugar in the funnel - draw the pendulum aside from its equilibrium position - and let it go. Sand pours out and the pendulum bob executes interesting gyrations. We have here compounded harmonic motions. The result is a figure of great beauty. These figures are called Lissajous Figures.

B - A glass tube has within it a metal rod. This metal rod is damped at its midpoint. In the glass tube we lay out some cork-dust. We now stroke the metal rod with a cloth bearing resin (or rosin) and an amazing thing ensues: The cork dust takes up very unique positions in the glass tube. What happens is this - briefly: The cloth with resin on it grabs the rod and lets go - grabs the rod and lets go — again our relaxation oscillation business. The compressional wave thus generated _m the rod "|umps off" the end of the rod - so to speak - travels to the far end of the glass tube -which is tightly closed with a stopper - and is reflected. This reflected wave or pulse joins hands with the incident wave to give rise to a standing wave - which we see in the configurations the cork dust takes up. And what can we do with all this? Answer: Determine the velocity of sound in the metal rod. This tube is known as Kundt's Tube.

C - An array of bar magnets hanging on strings permits the showing of a
compressional wave advancing. One magnet is pulled aside at the very end of the array and let go. It approaches its neighbor and drives it away - since the plarization is aligned this way. The pulse goes down this array - and suffers reflection from the ."open" end. It can be observed that a change in phase accompanies this reflection.

D - We explore once again the vibrations of high-voltage cables. Dampers are fixed to these cables to reduce the amplitude of oscillation. We show dampers made in the USA - in Germany - in Sweden.

E - The BULL ROARER: A slender strip of wood or masonite is fixed to a string at one end. We swing the strip in a vertical circle. A sound is produced. The strip catches up the air and pushes it to¬gether thus giving rise to a pressure pulse. The effect depends on Bernoulli's Principle - which see in an earlier Lesson in Mechanics.
We close this series on SOUND AND WAVES by showing the CHLADNI PLATES once again for here lies extraordinary beauty and drama. It is this point of view that I urge on all who study anything for then the subject becomes FUN and ENJOYABLE and the SPIRIT is lifted up.

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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