B

Barometer

P = ρgh (mercury column)
Quick Reference
Formula / NotationP = ρgh (mercury column)
Also Known AsMercury barometer; aneroid barometer; Torricelli barometer; atmospheric pressure gauge

What is Barometer?

A barometer is a scientific instrument used to measure atmospheric (air) pressure. The most common type (Torricelli barometer) consists of a vertical glass tube filled with mercury, inverted into a dish of mercury. Atmospheric pressure supports the mercury column; standard pressure (1 atm) equals 760 mm of mercury (mmHg or torr).

Formula & Notation

P = ρgh (mercury column)

Other Names / Synonyms: Mercury barometer; aneroid barometer; Torricelli barometer; atmospheric pressure gauge

Properties & Characteristics

1 atm = 760 mmHg = 101,325 Pa; mercury barometers: height of Hg column measures pressure; aneroid barometers: mechanical (no liquid); pressure = ρgh (density × gravity × height); units: mmHg, torr, Pa, atm, bar, inHg

Uses & Applications

Meteorology (weather forecasting); aviation (altimetry); industrial process control; laboratory measurements of gas pressure; clinical blood pressure measurement (sphygmomanometer uses similar principle)

Safety Information

Mercury barometers contain liquid mercury — highly toxic. Avoid breakage; mercury vapour is poisonous. In modern labs, aneroid or digital barometers are preferred. Proper disposal of mercury barometers required according to local regulations.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Barometer
Formula P = ρgh (mercury column)
Synonyms Mercury barometer; aneroid barometer; Torricelli barometer; atmospheric pressure gauge

Frequently Asked Questions

A barometer is a scientific instrument used to measure atmospheric (air) pressure. The most common type (Torricelli barometer) consists of a vertical glass tube filled with mercury, inverted into a dish of mercury. Atmospheric pressure supports the mercury column; standard pressure (1 atm) equals 760 mm of mercury (mmHg or torr).

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