
Lecture Description
We ask: By what physical properties or processes can we investigate the nature of HEAT and TEMPERATURE? What does NATURE do to demonstrate changes in temperature?
A. Expansion is a thermometric process. Evidence: a mercury-in-
glass thermo-meter — note the spelling! - shows an expanding
length of mercury column when the thermometer is immersed in
hot water - say.
B. Electrical Resistance is a thermometric property. We show a coil
of wire connected in series with an automobile lamp and a car battery. At room temperature the coil resistance is such that the lamp
lights at normal brightness. If now we put some ice - or "dry ice"
- solid CO2 - on the coil - the lamp lights brighter. On the
other hand if we heat the coil with a flame the light goes dimmer.
The mathematical expression for the behavior of a coil - of a metallic conductor - is this:
Rt = Ml +c^) where «C is called the temperature coefficient of resistance. For most metallic conductors this has the value 0.00366 - which comes out to be very nearly 1/273. This reveals that the electrons in a wire behave very much like the molecules In a gas! A very exciting thing to discover!
C. Magnetism is a thermometric property. If a bar of magnetic material
- iron - say - is held by a magnet and the bar is heated - the
magnetic forces get less. Roughly speaking this suggests the follow¬
ing: A magnetized sample of stuff implies an orderly arrangement of
the elementary parts. When heated a state of disorder arises.
D. Thermoelectric "power" is a thermometric process. If we connect
any two different wires and have their junctions at different temperatures a difference of potential arises and an electric current
ensues. We show an array of thermocouples - one whose scale is
thermometric - that is - it reads in degrees.
E. Color is a thermometric property. If we lay out on a clean fresh snow bank an array of colored sheets of paper - in the full sun -we see an astonishing thing: the paper sinks in the snow - mean¬ing of course that the snow is being melted underneath. And the different colored sheets sink at different rates.
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.