A strain gauge is defined as “any instrument or device that is used to measure the linear deformation in a given gauge length when it is subjected to loading”.
Characteristics of strain gauges
The distance between two knife edges in contact with specimen and the width of the movable knife edge.
The maximum strain that can be measured without resetting or replacing the strain gauge.
The smallest value of which can be read on the scale of the strain gauge.
Ability of the instrument to measure the linear deformation without error.
Ability of the strain gauge to give same measured reading for number of times. It does not vary due to temperature change, wear in mechanism, slippage, deflection of the components….etc