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 by adjusting R₃. R₁ = 20 Ω, R₂ = 50 Ω and R₄ = 120 Ω. Find the setting R₃.

R₁ = 20 ΩR₂ = 50 ΩR₄ = 120 Ω

R₃ = Ω

2.Easy

In the bridge shown, V_s = 12 V, R₁ = 120 Ω and R₂ = 1000 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 12 VR₁ = 120 ΩR₂ = 1000 ΩR₃ = 40 ΩR₄ = 200 Ω

V_a = V

3.Medium

A bridge has four 1000 Ω arms and V_s = 2 V. The sensor R₂ increases by ΔR = 2 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 2 VR = 1000 ΩΔR = 2 Ω

V_ab = mV

4.Medium

Find the Thévenin resistance R_th of the bridge shown, seen from the output terminals a and b.

V_s = 15 VR₁ = 20 ΩR₂ = 200 ΩR₃ = 300 ΩR₄ = 10 Ω

R_th = Ω

5.Hard

A quarter bridge (one active gauge, GF = 2) is excited with 3 V. The largest strain to be measured is 250 µε, and it must give 5 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 3 VGF = 2ε_max = 250 µεV_FS = 5 V

G =

6.Hard

A bridge with 120 Ω arms is excited with 10 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 = 10 VGF = 2ε = 800 µε

V_o = mV

Answer key

1. R₃ = 48 Ω
2. V_a = 10.71 V
3. V_ab = 1 mV
4. R_th = 27.86 Ω
5. G = 13333
6. V_o = 16 mV

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