Topic: Electronic Measurements and Instrumentation
A strain gauge with a gauge factor of 2.0 is connected in a Wheatstone bridge and subjected to a strain of 250 \mu\epsilon. What is the relative change in resistance (AR/R) of the gauge?
- A. 250 ppm
- B. 125 ppm
- C. 500 ppm
- D. 1000 ppm
Answer: C. 500 ppm
Explanation: The Gauge Factor (GF) is defined as the ratio of relative change in resistance to the mechanical strain: $GF = \frac{\Delta R / R}{\epsilon}$.
Rearranging gives $\frac{\Delta R}{R} = GF \times \epsilon$.
Substituting the given values: $\frac{\Delta R}{R} = 2.0 \times 250 \times 10^{-6} = 500 \times 10^{-6}$.
In parts per million (ppm), $500 \times 10^{-6}$ is equal to 500 ppm.