The resistance of a 125 Ω strain gauge changes by 1 ohm for 4000 micro strain. The gauge factor is1.522.535

The gauge factor, also known as the strain sensitivity, is defined as the ratio of fractional change in electrical resistance to the fractional change in length (strain).

The formula to calculate the gauge factor (GF) is:

GF = (ΔR/R) / ε

where: ΔR is the change in resistance, R is the initial resistance, and ε is the strain.

In this case, ΔR = 1 ohm, R = 125 ohms, and ε = 4000 micro strain = 4000 x 10^-6 = 0.004.

Substituting these values into the formula gives:

GF = (1/125) / 0.004 = 2.

Therefore, the gauge factor is 2.