It is absolutely essential that we UNDERSTAND these IDEAS - that the MEANING of the terms be "loud and clear" - and so we show an array of DEMONSTRATIONS to distinguish the commonplace notions of HEAT and TEMPERATURE.
A. In the very first demonstration we show a sealed glass tube containing a bit of mercury and some tiny glass chips. We heat the tube gently. The MOTION of the STUFF increases. Some of the mercury is vaporized - since the tube was somewhat pumped down before sealing - and the mercury vapor PUSHES the glass chips into great agitation. The higher the TEMPERATURE the greater the agitation. As the system cools down - as we say - the system gets quieter and quieter. HEAT|SA~M0DE OF MOTION. (You will observe that when I represent the addition of HEAT ENERGY to a system I show a candle flame. This is a tribute to Michael Faraday who gave six one-hour lectures on a CANDLE.) The phrase HEAT IS A MODE OF MOTION was first advanced by one of the BERNOULLI family - that family of one hundred or more geniuses!
B. We heat an array of various spheres of stuff in a beaker of water. After some time we agree that they are all at the SAME TEMPERATURE - being - as we say - heated through. We now place them on a slab of paraffin and an astonishing thing is witnessed. They sink to different levels - to different depths. That is - they MELT different amounts of paraffin. That is - they DO DIFFERENT AMOUNTS OF WORK. They therefore contained DIFFERENT AMOUNTS OF HEAT ENERGY. But they were all at the SAME TEMPERATURE. Thus we distinguish HEAT and TEMPERATURE.
C. Again - to distinguish HEAT and TEMPERATURE: We have two ordinary potatoes - a BIG one and a SMALL one. We have baked these - so we IMAGINE - IMAGINATION IS A VERY NECESSARY INGREDIENT of our work - and they are therefore at the SAME TEMPERATURE. But - clearly - there is vastly MORE HEAT ENERGY in the bigger one.
D. We have two beakers - one with a little water - one with much water - and a thermometer tells us that they are at the SAME TEMPERATURE. But they have DIFFERENT HEAT ENERGIES. E. Again we have two beakers - one with a little water - one with much water - and a thermometer tells us that the LITTLE water is at a HIGHER TEMPERATURE. These systems could have the same amount of HEAT ENERGY. By the TEMPERATURE of a system we will mean this: The average kinetic energy of the elementary parts - 1/2 mv^2 - the bar over the v meaning average v. By the HEAT - or HEAT ENERGY of a system we will mean this: the SUM of all the kinetic energies of these elementary parts.
F. We have a beaker with ice cubes in it. The thermometer reads 0°C. This is the TEMPERATURE of the system. Now let us add some thermal energy - some HEAT ENERGY - to the system - as by heating below with a candle flame - and what do we see happen? The TEMPERATURE remains unchanged as long as there is any ice. We are adding HEAT ENERGY but NOT changing the TEMPERATURE. The heat energy being added serves only to change the STATE - not the TEMPERATURE. The heat energy of the system is getting more but the temperature is not changed.
G. We have two beakers with water: One is cold water - one is hot water. We drop into each a bit of red dye. The diffusion takes place at different rates - faster in the hotter system. The motion in the hotter system is the faster.
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.