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 = 1000 Ω and R₂ = 80 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 3 VR₁ = 1000 ΩR₂ = 80 ΩR₃ = 400 ΩR₄ = 80 Ω

V_a = V

2.Easy

The Wheatstone bridge in the diagram is balanced: the galvanometer reads zero. R₁ = 200 Ω, R₂ = 80 Ω and R₃ = 250 Ω. Find the unknown resistor R₄.

R₁ = 200 ΩR₂ = 80 ΩR₃ = 250 Ω

R₄ = Ω

3.Medium

A galvanometer with a resistance of 200 Ω is connected between a and b of the bridge shown (V_s = 9 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 9 VR₁ = 20 ΩR₂ = 200 ΩR₃ = 500 ΩR₄ = 150 ΩR_g = 200 Ω

I_g = µA

4.Medium

A 470 Ω strain gauge is one arm (R₂) of a bridge with four equal 470 Ω arms and an excitation of 5 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 5 VR = 470 Ω

P_g = mW

5.Hard

A bridge with 350 Ω arms is excited with 3 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2 and the strain is 750 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2ε = 750 µε

V_o = mV

6.Hard

A bridge with 350 Ω arms is excited with 5 V and has one active gauge (quarter bridge). The gauge factor is 2.12 and the strain is 500 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2.12ε = 500 µε

V_o = mV

Answer key

1. V_a = 0.2222 V
2. R₄ = 100 Ω
3. I_g = 18302 µA
4. P_g = 13.3 mW
5. V_o = 4.5 mV
6. V_o = 1.325 mV

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