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 = 6 V, R₁ = 400 Ω and R₂ = 50 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 6 VR₁ = 400 ΩR₂ = 50 ΩR₃ = 300 ΩR₄ = 200 Ω

V_a = V

2.Easy

In the bridge shown, V_s = 15 V, R₁ = 10 Ω and R₂ = 80 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 15 VR₁ = 10 ΩR₂ = 80 ΩR₃ = 100 ΩR₄ = 250 Ω

V_a = V

3.Medium

A bridge has four 100 Ω arms and V_s = 6 V. The sensor R₂ increases by ΔR = 10 Ω. Find the exact output V_ab in mV.

V_s = 6 VR = 100 ΩΔR = 10 Ω

V_ab = mV

4.Medium

A 100 Ω strain gauge is one arm (R₂) of a bridge with four equal 100 Ω arms and an excitation of 6 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 6 VR = 100 Ω

P_g = mW

5.Hard

A quarter bridge (one active gauge, GF = 2) is excited with 3 V. The largest strain to be measured is 400 µε, and it must give 3.3 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 3 VGF = 2ε_max = 400 µεV_FS = 3.3 V

G =

6.Hard

A bridge with 120 Ω arms is excited with 3 V and has one active gauge (quarter bridge). The gauge factor is 2.12 and the strain is 400 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2.12ε = 400 µε

V_o = mV

Answer key

1. V_a = 0.6667 V
2. V_a = 13.33 V
3. V_ab = 142.9 mV
4. P_g = 90 mW
5. G = 5500
6. V_o = 0.636 mV

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