
Lecture Description
Soap Bubbles and Soap Films are not for child's play alone. Their study reveals some very important principles of Nature. Principal among these is this: That the Energy of a System tends toward Least. That is - the Energy of a System left to itself goes downhill. This is why raindrops are spherical; this is why a drop of water or a drop of mercury flattens out when it gets bigger. We show an array of exciting things:
A - THE DOUBLE BUBBLE PARADOX: We blow a small soap bubble and a big_ soap bubble simultaneously. Then we allow the two to be connected with each other. And a most remarkable thing happens! The SMALL one blows the BIG one bigger! We thus discover that the pressure in the smaller bubble is the greater. Which is NOT what most people think!
B - We fill a vessel very very full with water - so full in fact that it is
"humped up" high above the edge of the vessel. The surface behaves as a tight membrane - a stretched film - and is so strong in fact that we can float a steel needle on it!
C - We show some mercury droplets on a clean glass plate. When small they
are round; when bigger they flatten out. When two bubbles are brought very near to each other they coalesce - that is - they swiftly go together and become one. This action is incredibly swift and is most certainly electrical in nature.
D - We show an array of wire frames of various geometries dipped into a vat of soap solution. The soap films formed are very beautiful to see. When any one is punctured - broken - all the rest quickly take up a form such that the Energy of the System is again a minimum.
E - A circular frame has a loose string across a diameter. A soap film is formed covering the frame and the string. When the film is punctured at any spot the string instantly goes into a circular arc since a circular shape represents least Energy.
F - When a narrow small-bore tube - like a glass-tube - is dipped into water the water climbs INSIDE the tube higher than it is outside the tube. When this is done with mercury the mercury inside the tube is lower than the mercury level outside the tube. And the surface of the water is concave upward whereas the surface of the mercury is concave downward" We show this surface curvature with two wedge-shaped vessels.
Soap Films and Soap Bubbles and Drops are wonderful to play with and exciting to explore. Everyone - young and old - should read SOAP BUBBLES by C.V. Boys. Professor Boys describes hundreds of experiments which can be done at home or in school with utterly simple apparatus.
Course Index
- The Idea of the Center of Gravity
- Newton's First Law of Motion: Inertia
- Newton's Second Law of Motion: The Elevator Problem
- Newton's Third Law of Motion: Momentum
- Energy and Momentum
- Concerning Falling Bodies & Projectiles
- The Simple Pendulum and Other Oscillating Things
- Adventures with Bernoulli: Bernoulli's Principle
- Soap Bubbles and Soap Films
- Atmospheric Pressure
- Centrifugal Force and Other Strange Matters
- The Strange Behavior of Rolling Things
- Archimedes' Principle
- Pascal's Principle: The Properties of Liquids
- Levers, Inclines Planes, Geared-wheels and Other Machines
- The Ideas of Heat and Temperature
- Thermometric Properties and Processes
- How to Produce Heat Energy
- Thermal Expansion of Stuff: Solids
- Thermal Expansion of Stuff: Gases & Liquids
- The Strange Thermal Behavior of Ice and Water
- Heat Energy Transfer by Conduction
- Heat Energy Transfer by Convection
- Heat Energy Transfer by Radiation
- Evaporation, Boiling, Freezing: A Dramatic Adventure
- Miscellaneous Adventures in Heat
- The Drama in Real Cold Stuff: Liquid Nitrogen
- The Physics of Toys: Mechanical
- The Physics of Toys: Acoustic and Thermal
- Waves: Kinds of Properties
- Sound Waves: Sources of Sound & Pitch and Frequency
- Vibrating Bars and Strings: The Phenomenon of Beats
- Resonance: Forced Vibrations
- Sounding Pipes
- Vibrating Rods and Plates
- Miscellaneous Adventures in Sound
- Electrostatic Phenomena: Foundations of Electricity
- Electrostatic Toys, Part 1
- Electrostatic Toys, Part 2
- Adventures with Electric Charges
- Adventures in Magnetism
- Ways to "Produce" Electricity
- Properties and Effects of Electric Currents
- Adventures in Electromagnetism
- Further Adventures in Electromagnetism
- 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.