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 = 10 V.

V_s = 10 VR₁ = 600 ΩR₂ = 150 ΩR₃ = 400 ΩR₄ = 200 Ω

V_ab = V

2.Easy

The Wheatstone bridge in the diagram is balanced: the galvanometer reads zero. R₁ = 50 Ω, R₂ = 600 Ω and R₃ = 20 Ω. Find the unknown resistor R₄.

R₁ = 50 ΩR₂ = 600 ΩR₃ = 20 Ω

R₄ = Ω

3.Medium

A 1000 Ω strain gauge is one arm (R₂) of a bridge with four equal 1000 Ω arms and an excitation of 10 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 10 VR = 1000 Ω

P_g = mW

4.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 = 200 ΩR₂ = 400 ΩR₃ = 20 ΩR₄ = 300 ΩR_g = 200 Ω

I_g = µA

5.Hard

A bridge with 1000 Ω arms is excited with 10 V and has one active gauge (quarter bridge). The gauge factor is 2 and the strain is 500 µε. Find the bridge output V_o in mV.

V_s = 10 VGF = 2ε = 500 µε

V_o = mV

6.Hard

A bridge with 350 Ω arms is excited with 3 V and has one active gauge (quarter bridge). The gauge factor is 2.1 and the strain is 1500 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2.1ε = 1500 µε

V_o = mV

Answer key

1. V_ab = −1.333 V
2. R₄ = 240 Ω
3. P_g = 25 mW
4. I_g = −3846 µA
5. V_o = 2.5 mV
6. V_o = 2.363 mV

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