UPSC 2016 CDS II GK Paper

The pressure exerted by a 760 mm column of mercury at 0 °C is known as 1 atmosphere. Pressure is defined as force per unit area. When a gas is enclosed in a container, it exerts uniform outward force (i.e., pressure) on the walls of the container in all directions. Pressure is measured in terms of atmospheric pressure, which is the pressure exerted by the gases on the surface of the earth. Atmospheric pressure is measured by a simple device known as a mercury barometer.