This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
A manometer is like the blood pressure meter that a doctor uses to measure BP. It has a vertical column of a liquid in a thin glass tube of circular cross section.

For measuring blood pressure the liquid used is mercury. It has a density of 13.600 kg/m^3.  A manometer can be also used to measure the atmospheric pressure.

The pressure P exerted by the column of liquid of height is measured by the weight W of the liquid and the area of cross section A of the tube:

       Pressure = P = W / A = density * volume * g / A = density * Height * g

For measuring atmospheric pressure, we have a closed glass tube placed in a wide beaker or container filled with mercury exposed to the atmosphere. Then the mercury in the tube raises by 760 mm above the level outside the tube, then

       P = 13,600 * 0.760 * 9.8 = 1.0129 * 10^5 Pa