Wheatstone bridge & strain gauges worksheet with answers

Free printable Wheatstone bridge & strain gauges worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 2 V.

V_s = 2 VR₁ = 250 ΩR₂ = 150 ΩR₃ = 80 ΩR₄ = 250 Ω

V_ab = V

2.Easy

In the bridge shown, V_s = 5 V, R₁ = 800 Ω and R₂ = 60 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 5 VR₁ = 800 ΩR₂ = 60 ΩR₃ = 1000 ΩR₄ = 150 Ω

V_a = V

3.Medium

Find the Thévenin resistance R_th of the bridge shown, seen from the output terminals a and b.

V_s = 2 VR₁ = 20 ΩR₂ = 500 ΩR₃ = 120 ΩR₄ = 600 Ω

R_th = Ω

4.Medium

A 200 Ω strain gauge is one arm (R₂) of a bridge with four equal 200 Ω arms and an excitation of 6 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 6 VR = 200 Ω

P_g = mW

5.Hard

A bridge with 350 Ω arms is excited with 3 V and has one active gauge (quarter bridge). The gauge factor is 2 and the strain is 200 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2ε = 200 µε

V_o = mV

6.Hard

A quarter bridge with one active gauge (GF = 2.12) is excited with 2.5 V. Under load the output reads 0.331 mV. Find the strain ε in µε.

V_s = 2.5 VGF = 2.12V_o = 0.331 mV

ε = µε

Answer key

1. V_ab = −0.7652 V
2. V_a = 0.3488 V
3. R_th = 119.2 Ω
4. P_g = 45 mW
5. V_o = 0.3 mV
6. ε = 249.8 µε

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