Question

The liquid/liquids used in simple barometer is/are
1. water
2. mercury
3. alcohol
4. All of the above

Answer 1

Correct Answer - Option 2 : mercury

The correct answer is Mercury.

• Mercury is commonly used in barometers because its high density means the height of the column can be a reasonable size to measure atmospheric pressure.
• If water is used in the barometer, it would need to be 13.6 times taller than a mercury barometer to obtain the same pressure difference.
• A standard mercury barometer to measure atmospheric pressure is a tube with one end sealed.
• The sealed end is close to zero pressure, while the other end is open to the atmosphere.

• Alcohol is not used in barometer because:
  •  It cannot measure the high temperatures because of its low boiling point.
  • It makes the wall wet.
  • It is colorless and thus dye must be added to it so as to make it visible.