Monday, October 25, 2010


Relation between Temperature and Heat

Temperature - a physical property that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot.

The temperature of an ideal monatomic gas is related to the average kinetic energy of its atoms. In this animation, the size of helium atoms relative to their spacing is shown to scale under 1950 atmospheres of pressure. These atoms have a certain, average speed (slowed down here two trillion fold from room temperature).

Heat - energy transferred from one body or thermodynamic system to another due to thermal contact when the systems are at different temperatures. It is also often described as the process of transfer of energy between physical entities.

Heat generated from the infrared electromagnetic radiation from the Sun is one of the driving forces of life on Earth.

Physical properties that change with temperature:

1)Volume of a fixed mass of liquid
e.g. Mercury-in-glass thermometer, Alcohol-in-glass thermometer

2)Electrical voltage or electromotive force(e.m.f)
e.g. Thermocouple

3)Electrical Resistance of a piece of metal
e.g. Resistance thermometer

4)Pressure of a fixed mass of gas at constant volume
e.g. Constant-volume gas thermometer

What makes a good Thermometer?

1) An easy-to-read scale
2) Safe to use
3) Responsive to temperature changes
4) Sensitive to small temperature changes
5) Able to measure a wide range of temperatures

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