13. The ‘liquid-in-glass’ thermometer


The Liquid-in-Glass Thermometer

A liquid in glass thermometer can be used to measure temperature. They are the standard thermometers with which you are probably familiar, and are quite fragile, being made out of glass.

As the temperature rises, the liquid inside the thermometer (either mercury or alcohol) will expand up the narrow tube. This is because the particles of liquid move around faster at a higher temperature and so take up more space.

The narrower the tube is, the further the liquid will move up the tube for each degree Celsius rise in temperature.

The amount of expansion of the liquid can be matched to a certain temperature by marking a scale onto the thermometer beside the tube to measure the height of the liquid. The process of matching this scale to particular temperatures is called calibration, so that the scale accurately reflects the temperature that the thermometer is measuring.

The bottom reservoir of liquid is called the 'bulb'.

GCSE Physics Keywords: Liquid-in-glass, Thermometer, Expansion, Temperature, Callibration

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