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 = 2 V, R₁ = 40 Ω and R₂ = 10 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 2 VR₁ = 40 ΩR₂ = 10 ΩR₃ = 500 ΩR₄ = 60 Ω

V_a = V

2.Easy

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 9 V.

V_s = 9 VR₁ = 250 ΩR₂ = 40 ΩR₃ = 120 ΩR₄ = 10 Ω

V_ab = V

3.Medium

A 330 Ω strain gauge is one arm (R₂) of a bridge with four equal 330 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 = 330 Ω

P_g = mW

4.Medium

A galvanometer with a resistance of 50 Ω is connected between a and b of the bridge shown (V_s = 10 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 10 VR₁ = 20 ΩR₂ = 250 ΩR₃ = 100 ΩR₄ = 150 ΩR_g = 50 Ω

I_g = µA

5.Hard

A bridge with 120 Ω arms is excited with 2.5 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2.1 and the strain is 750 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2.1ε = 750 µε

V_o = mV

6.Hard

A quarter bridge (one active gauge, GF = 2) is excited with 10 V. The largest strain to be measured is 750 µε, and it must give 5 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 10 VGF = 2ε_max = 750 µεV_FS = 5 V

G =

Answer key

1. V_a = 0.4 V
2. V_ab = 0.5491 V
3. P_g = 3.03 mW
4. I_g = 25360 µA
5. V_o = 3.938 mV
6. G = 1333

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