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 = 3 V, R₁ = 300 Ω and R₂ = 120 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 3 VR₁ = 300 ΩR₂ = 120 ΩR₃ = 150 ΩR₄ = 600 Ω

V_a = V

2.Easy

In a slide-wire (metre) bridge a known 20 Ω resistor sits in the left gap and an unknown resistor Rₓ in the right gap. The galvanometer reads zero when the jockey is 60 cm from the left end A of the 100 cm wire. Find R_x.

R = 20 Ωl = 60 cmL = 100 cm

R_x = Ω

3.Medium

A bridge with four 500 Ω arms is supplied with 3 V. When the sensor R₂ changes, the output reads V_ab = 7.46 mV. Find the exact change ΔR of R₂.

V_s = 3 VR = 500 ΩV_ab = 7.46 mV

ΔR = Ω

4.Medium

A bridge has four 470 Ω arms and V_s = 15 V. The sensor R₂ increases by ΔR = 117.5 Ω. Find the exact output V_ab in mV.

V_s = 15 VR = 470 ΩΔR = 117.5 Ω

V_ab = mV

5.Hard

A bridge with 120 Ω arms is excited with 10 V and has one active gauge (quarter bridge). The gauge factor is 2.12 and the strain is 1200 µε. Find the bridge output V_o in mV.

V_s = 10 VGF = 2.12ε = 1200 µε

V_o = mV

6.Hard

A 120 Ω strain gauge with gauge factor 2 is bonded to a steel bar. Under load its resistance rises by 0.24 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2ΔR = 0.24 Ω

ε = µε

Answer key

1. V_a = 0.8571 V
2. R_x = 13.33 Ω
3. ΔR = 4.998 Ω
4. V_ab = 833.3 mV
5. V_o = 6.36 mV
6. ε = 1000 µε

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