A strain gauge of resistance 120 and gauge factor 2.0 is at zero strai...
Gauge Factor, G
f =
2 =
=
= -300 μ
m/m
Negative Sign shows compressive strain.
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A strain gauge of resistance 120 and gauge factor 2.0 is at zero strai...
Gauge Factor, G
f =
2 =
=
= -300 μ
m/m
Negative Sign shows compressive strain.
A strain gauge of resistance 120 and gauge factor 2.0 is at zero strai...
Calculation:
- The equivalent resistance of the parallel combination of the strain gauge (120 ohms) and the fixed resistance (200 kΩ) can be calculated using the formula:
\[
R_{eq} = \frac{R_1 \times R_2}{R_1 + R_2}
\]
- where \(R_1 = 120 \Omega\) and \(R_2 = 200 k\Omega = 200,000 \Omega\).
- Substituting the values into the formula:
\[
R_{eq} = \frac{120 \times 200,000}{120 + 200,000} = \frac{24,000,000}{200,120} \approx 119.95 \Omega
\]
Strain Calculation:
- The gauge factor (GF) is given as 2.0, which means that for a strain of 1 unit, the resistance changes by a factor of 2.0 times the initial resistance.
- The change in resistance (\(\Delta R\)) due to strain can be calculated using the formula:
\[
\Delta R = GF \times R_0 \times \epsilon
\]
- where \(R_0 = 120 \Omega\) is the initial resistance and \(\epsilon\) is the strain.
- In this case, the equivalent resistance (\(R_{eq}\)) of the parallel combination is 119.95 ohms.
- Substituting the values into the formula:
\[
119.95 = 2.0 \times 120 \times \epsilon
\]
- Solving for \(\epsilon\):
\[
\epsilon = \frac{119.95}{240} \approx 0.4998
\]
- The equivalent strain is -0.4998, which is approximately -300 μm/m.
Therefore, the correct answer is option D: \(-300 \mu m/m\).