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

In the bridge shown, V_s = 6 V, R₁ = 20 Ω and R₂ = 250 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 6 VR₁ = 20 ΩR₂ = 250 ΩR₃ = 60 ΩR₄ = 600 Ω

V_a = V

2.Easy

In the bridge shown, V_s = 15 V, R₁ = 150 Ω and R₂ = 20 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 15 VR₁ = 150 ΩR₂ = 20 ΩR₃ = 50 ΩR₄ = 200 Ω

V_a = V

3.Medium

A galvanometer with a resistance of 200 Ω is connected between a and b of the bridge shown (V_s = 5 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 5 VR₁ = 10 ΩR₂ = 120 ΩR₃ = 80 ΩR₄ = 250 ΩR_g = 200 Ω

I_g = µA

4.Medium

A 1000 Ω strain gauge is one arm (R₂) of a bridge with four equal 1000 Ω arms and an excitation of 2 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 2 VR = 1000 Ω

P_g = mW

5.Hard

A quarter bridge with one active gauge (GF = 2.1) is excited with 5 V. Under load the output reads 0.525 mV. Find the strain ε in µε.

V_s = 5 VGF = 2.1V_o = 0.525 mV

ε = µε

6.Hard

A bridge with 120 Ω arms is excited with 5 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2 and the strain is 800 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2ε = 800 µε

V_o = mV

Answer key

1. V_a = 5.556 V
2. V_a = 1.765 V
3. I_g = 3067 µA
4. P_g = 1 mW
5. ε = 200 µε
6. V_o = 8 mV

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