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GATE 2025 IN – Question 15

Sensors and Industrial Instrumentation · Resistive capacitive and inductive sensors · 1 mark · Multiple choice

Four identical strain gauges S1, S2, S3, and S4 are mounted on the cantilever force transducer at equal distance from its base. S1 and S2 are on the top surface; S3 and S4 are on the bottom surface, as shown in Figure (a). They are to form the four arms A, B, C, and D of the Wheatstone bridge in Figure (b). Which assignment maximizes measurement sensitivity?

Diagram for GATE 2025 IN question 15
  1. A → S1, B → S2, C → S4, D → S3
  2. A → S1, B → S4, C → S3, D → S2
  3. A → S1, B → S2, C → S3, D → S4
  4. A → S1, B → S4, C → S2, D → S3

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Show answer and explanation

Correct answer: (D) A → S1, B → S4, C → S2, D → S3

Explanation

The two top gauges have the same strain sign and the bottom pair the opposite sign.

For all four contributions to add, same-sign gauges must occupy opposite bridge arms.

D places S1/S2 in A/C and S4/S3 in B/D, so tension and compression reinforce the differential output.

Hence **D**.