Subtopic: Measurement of force, stress, torque, speed, displacement and acceleration on machine elements – shafts, couplings, keys, bearings and knuckle joints
Question Statement:
In a full-bridge electrical strain gauge circuit mounted on a rotating shaft to measure torque, how many active strain gauges are used at $45^\circ$ helix angles?
Options:
(A) 4 gauges (2 in tension, 2 in compression providing temperature compensation and $4\times$ sensitivity)
(B) 1 gauge
(C) 2 gauges
(D) 3 gauges
Answer Key:
A
Step-by-Step Solution & Explanation
A full Wheatstone bridge with four $45^\circ$ gauges cancels axial bending and temperature effects while quadrupling torsional output sensitivity.