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IGCSE Physics, Cambridge 0625, Malaysia

Barometer

An instrument used to measure atmospheric pressure, typically using a column of mercury.

A mercury barometer consists of a glass tube closed at one end, filled with mercury, and inverted into a dish of mercury. Atmospheric pressure supports the mercury column.

At sea level, the mercury column is approximately 760 mm high. Higher atmospheric pressure pushes the mercury higher; lower pressure allows it to fall.

The pressure is calculated using p=ρghp = \rho g h, where ρ\rho is the density of mercury (13 600 kg/m3^3).

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