Question

What would happen when we use water instead of murcury in tharmamiter

Answer 1

Liquid pressure is given by

P = h*d*g

where,

h = height of column
d = density of liquid
g = acceleration due to gravity


The density of Mercury is 13.54 g/cm^3.

The density of water is 1 g/cm^3.


So in order to express the same pressure indicated by the mercury barometer, a water barometer needs 13 times more amount of water.

Or using the same amount of water as that of mercury, we need a barometer which has 13 times more height.


Also mercury exhibits excellent capillary rise, which is not very profound in the case of water.


Hence by all means, use of water in a barometer is not practical.