ABSTRACT
Sensors can be understood best by examining the basic physical principles upon which they are designed. In this chapter, some sensors involved in the measurement of length, relative displacement, force, pressure, acceleration, sound pressure, velocity, volumetric and mass flow rates, temperature, heat flux, relative humidity, circular frequency, particle diameter, void fraction, density, density gradient, gas concentration, and pH are presented. The fundamental equations that relate what is sensed to its measurable output are given for each sensor described.
