Principles of measurement

Abstract

Measurements may be made for a number of reasons including:

• Fair trade — this is the oldest reason for measuring. In the 8th century BC, the prophet Micah wrote ‘Can I overlook the infamous false measure, the accursed short bushel? Can I connive at false scales or a bag of light weights?’ Micah Ch. 6, v. 10–11 (New English Bible).

• To make the components in a system compatible. For example, a door must fit in its frame, or a nut must screw on a bolt. Similarly, the supply voltage to an IC must not be large enough to cause damage or so small that the IC will not work. Accurate and reliable measurements were the precursors of mass production in both electrical and mechanical engineering.

• To permit control or to make the conditions correct. Many processes work best at a particular temperature, so the temperature has to be measured to control the heat input and maintain the optimum temperature.