The liquids shown in figure in the two arms are mercury (specific gravity =13.6) and water. If the difference of heights of the mercury columns is 2 cm, find the height of the water column.
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Explanation

Suppose the atmospheric pressure `=P_0`
Pressure at `A=P_0_h(1000kgm^-3)g`.
Pressure `at B=P_0+(0.02m)(13600kgm^-3)g`
These pressures are equal as A and B are at the same horizontal leel. Thus,
`h=(0.02 m) 13.6` ltbr `=0.27m = 27cm`