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 = 100 Ω and R₂ = 200 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 3 VR₁ = 100 ΩR₂ = 200 ΩR₃ = 40 ΩR₄ = 200 Ω

V_a = V

2.Easy

The Wheatstone bridge in the diagram is balanced: the galvanometer reads zero. R₁ = 150 Ω, R₂ = 150 Ω and R₃ = 60 Ω. Find the unknown resistor R₄.

R₁ = 150 ΩR₂ = 150 ΩR₃ = 60 Ω

R₄ = Ω

3.Medium

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

V_s = 6 VR₁ = 150 ΩR₂ = 40 ΩR₃ = 800 ΩR₄ = 40 Ω

R_th = Ω

4.Medium

A 200 Ω strain gauge is one arm (R₂) of a bridge with four equal 200 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 = 200 Ω

P_g = mW

5.Hard

A bridge with 350 Ω arms is excited with 5 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2 and the strain is 400 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2ε = 400 µε

V_o = mV

6.Hard

A bridge with 120 Ω arms is excited with 5 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2.05 and the strain is 1500 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2.05ε = 1500 µε

V_o = mV

Answer key

1. V_a = 2 V
2. R₄ = 60 Ω
3. R_th = 69.67 Ω
4. P_g = 45 mW
5. V_o = 4 mV
6. V_o = 7.688 mV

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