Sat27November0445PM 6

By which of the following principles does a strain gauge work?

(Please select 1 option)

Absorption of gas by a crystal

Varying resistance of a wire when stretched Correct

Reduction of pressure at a constriction in a tube

Varying scatter of light molecules of different sizes

Uncoiling of a tube by pressurised gas

Explanation

When a wire is stretched it becomes longer and thinner and consequently its resistance increases, and this is the principle by which a strain gauge works.

A strain gauge acts as a resistor, which are used in pressure transducers. In a pressure transducer the diaphragm moves as the pressure changes and this alters the tension in the resistance wire, thus changing its resistance.

The changes in current flow through the resistor are then amplified and displayed as a measure of pressure change.

However, to measure or monitor these changes in resistance, a Wheatstone bridge is frequently used.

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Times answered: 248