Science Basics: Pressure

Introduction

Pressure Ulcers

Measurement

Blood Pressure

Units

Boyle's Law

Activity

Assessment

Resources

Feedback

Measurement

One way to measure pressure is to make a manometer by inverting a glas tube containing mercury into a container also containing mercury.

The heavy mercury column in the tube sinks, but the tube does not empty because of the effect of atmospheric pressure on the mercury in the container. The higher the atmospheric pressure the greater the height of the mercury column.

Consequently atmospheric pressure can be measured in terms of the height of the mercury column and at sea level it is about 760 millimetres of mercury (mmHg).