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 Wheatstone bridge in the diagram is balanced: the galvanometer reads zero. R₁ = 300 Ω, R₂ = 10 Ω and R₃ = 120 Ω. Find the unknown resistor R₄.

R₁ = 300 ΩR₂ = 10 ΩR₃ = 120 Ω

R₄ = Ω

2.Easy

In the bridge shown, V_s = 10 V, R₁ = 500 Ω and R₂ = 300 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 10 VR₁ = 500 ΩR₂ = 300 ΩR₃ = 800 ΩR₄ = 120 Ω

V_a = V

3.Medium

A bridge has four 1000 Ω arms and V_s = 5 V. The sensor R₂ increases by ΔR = 80 Ω. Find the exact output V_ab in mV.

V_s = 5 VR = 1000 ΩΔR = 80 Ω

V_ab = mV

4.Medium

A bridge has four 220 Ω arms and V_s = 12 V. The sensor R₂ increases by ΔR = 22 Ω. Find the exact output V_ab in mV.

V_s = 12 VR = 220 ΩΔR = 22 Ω

V_ab = mV

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 1200 µε. Find the bridge output V_o in mV.

V_s = 10 VGF = 2ε = 1200 µε

V_o = mV

6.Hard

A quarter bridge (one active gauge, GF = 2.1) 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 = 2.1ε_max = 750 µεV_FS = 5 V

G =

Answer key

1. R₄ = 4 Ω
2. V_a = 3.75 V
3. V_ab = 96.15 mV
4. V_ab = 285.7 mV
5. V_o = 6 mV
6. G = 1270

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