Chapter 10, Problem 5QP

Interpretation Introduction

Interpretation:

The reason for using mercury instead of water in a barometer is to be explained.

Concept introduction:

A barometer is an instrument, which is used to determine the atmospheric pressure via the height of ascent or descent of the mercury level in the tube.

The formula for calculating pressure via barometer is given as follows:

$\text{Pressure (}P\text{) = }h\rho g$

Here, $h$ is the height of the mercury column, $\rho$ is the density of the mercury, and $g$ is the acceleration due to gravity.

Height of the column can be calculated as

$\begin{array}{l}h\text{ = }\frac{P}{\rho g}\\ \text{Or,}\\ h\alpha \frac{1}{\rho }\end{array}$

If the density of the liquid is higher, then the height of the column will be less, and vice versa.