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

The bridge shown is supplied with V_s = 3 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 3 VR₁ = 120 ΩR₂ = 100 ΩR₃ = 150 ΩR₄ = 100 Ω

I_s = mA

2.Easy

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 6 V.

V_s = 6 VR₁ = 20 ΩR₂ = 1000 ΩR₃ = 40 ΩR₄ = 40 Ω

V_ab = V

3.Medium

A 350 Ω strain gauge is one arm (R₂) of a bridge with four equal 350 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 = 350 Ω

P_g = mW

4.Medium

A 200 Ω strain gauge is one arm (R₂) of a bridge with four equal 200 Ω arms and an excitation of 5 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 5 VR = 200 Ω

P_g = mW

5.Hard

A bridge with 350 Ω arms is excited with 2.5 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2.05 and the strain is 1200 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2.05ε = 1200 µε

V_o = mV

6.Hard

A bridge with 1000 Ω arms is excited with 5 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2.1 and the strain is 200 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2.1ε = 200 µε

V_o = mV

Answer key

1. I_s = 25.64 mA
2. V_ab = 2.882 V
3. P_g = 2.857 mW
4. P_g = 31.25 mW
5. V_o = 3.075 mV
6. V_o = 1.05 mV

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