2.3 Liquid Thermometer
The most common liquid thermometer is mercury-in-glass thermometer. This is very simple in construction and is widely used in laboratories. Mercury is put in a bulb of thin-walled glass tube with a graduated stem of uniform cross section. Its lower fixed point is marked zero after keeping the bulb in ice for some time when the mercury thread in the stem becomes steady. The thermometer is then introduced in a boiler where water is made to boil at one atmospheric pressure. When the position of the mercury thread becomes steady, it is marked 100°C and the length is divided into 100 equal parts.
Mercury has been chosen as the thermometric substance for the following reasons:
- It is obtained easily in pure state; it remains ...
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