Why Mercury or Alcohol is used in thermometers?

Mercury and Alcohol are used in the thermometer because they remain in liquid form with temperature change.

The best conductor of heat among liquids is mercury and also it does not stick to any surface, so it is widely used in thermometers

Even a small change in temperature changes the volume of the Alcohol or Mercury. By calculating the expansion of the liquid, the temperature is measured.

Properties of Mercury

  • The expansion of mercury is uniform in that is equal amounts of heat it expands by an equal length.
  • Mercury is opaque or non-transparent and shining or glossy.
  • Mercury does not stick to any surface, that is the glass surface of the thermometer.
  • It is a good conductor of heat.
  • It has a high boiling point of about 357° C and a low freezing point of about -39°C.
  • It has a wide range of temperatures.

Properties of Alcohol

  • The alcohol’s freezing point is less than -100° C. As a result, alcohol is used to measure very low temperatures.
  • Its expansion per degree Celsius rise is high.
  • It can be coloured brightly for visibility.

FAQ

  1. Mercury is used in thermometers because?

Mercury is used in thermometers because it is a metal that stays liquid in the room. As you know metals are good conductors of heat. Also, it has the property of a high coefficient of expansion. Even there is the slightest variation in temperature is noted by mercury so shows an immediate change. Also, it does not stick to any surface.

* * All the Notes in this blog, are referred from Tamil Nadu State Board Books and Samacheer Kalvi Books. Kindly check with the original Tamil Nadu state board books and Ncert Books.
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