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Measurement of Temperature

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-239

2025-11-20

602

The idea of the temperature of a body that we receive from our sensations is so dependent upon other things than the temperature, that it is frequently incorrect. What seems a high temperature to one person may seem a low temperature to another, and the same temperature seems different to us at one time from what it does at another. If one hand is wet and the other dry and both are held in the current of warm air coming from a register, the air will feel warm to the dry hand and cold to the wet hand. In this and similar ways we find that the body is not a good instrument with which to measure temperature. The instrument that is used for this purpose is called a thermometer. The principle employed is that of the unequal expansion of bodies when heated. The most common form is the mercury thermometer, which consists of a glass tube with thick walls and a small bore, blown into a bulb at one end for holding the mercury.