Resistance-Type Transducers:

Involving in this classification of transducers are strain gauges and moving contacts (slidewire variable resistors). Above figure describes a simple strain gauge. The strain gauge measures the external force (pressure) applied to a fine wire. Fine wire is commonly arranged in the form of a grid.  A pressure change causes a resistance change due to the distortion of the wire. The value of the pressure could be found through measuring the change in resistance of the wire grid. The Given Equation 2-1 displays the pressure to resistance relationship.

 R =     K (L/A)                                                                                              (2-1)

where

R = resistance of the wire grid in ohms

K = resistivity constant for the particular type of wire grid

L = length of wire grid

A = cross sectional area of wire grid