Suppose the pressure at the surface of mercury in as barometer tube is `P_1` and the pressure at the surface of mercury in the cup is `P_2`.

The pressure at sea surface ……. P_(a) .

A mercury barometer always reads less than actual pressure.

What will happen if water is used in place of mercury in a barometer tube?

The pressure given by a mercury barometer is always less than actual pressure. Why?

Why is the reading of a mercury barometer always less than actual pressure?

Measuring Pressure By Mercury Barometer

A barometer is constructed with its tube having radius 1.0 mm. Assume that the surface of mercury in the tube is spherical in shape. If the atmospheric pressure is equal to 76 cm of mercury, what will be the height raised in the barometer tube? The contact angle of mercury with glass 135^@ and surface tension of mercury =0.465Nm^-1 . Density of mercury =13600kgm^-3 .

A barometer is constructed with its tube having radius 1.0 mm. Assume that the surface of mercury in the tube is spherical in shape. If the atmospheric pressure is equal to 76 cm of mercury, what will be the height raised in the barometer tube? The contact angle of mercury with glass 135^@ and surface tension of mercury =0.466Nm^-1 . Density of mercury =13600kgm^-3 .