Question about using a wheatstone bridge to measure changes in resistance

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Homework Help Overview

The discussion revolves around the use of a Wheatstone bridge circuit for measuring small changes in resistance, specifically in the context of strain gauges. The original poster questions the necessity of the Wheatstone bridge compared to a direct measurement using a milliammeter.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to understand the advantages of a Wheatstone bridge over a simple current measurement method. Some participants question whether the primary benefit of the Wheatstone bridge is temperature compensation, while others explore the implications of this in their specific experimental context.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the role of the Wheatstone bridge and its relevance to their experiments. There is a lack of consensus on whether the Wheatstone bridge is necessary for measuring resistance changes in the context of temperature variations.

Contextual Notes

Participants are considering the effects of temperature on strain gauges and how this relates to their experimental setups. There is an indication that some may have specific constraints or requirements in their experiments that influence their approach to measurement.

gionex
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Hi

I need to measure the small changes in resistance of a strain gauge.

I have read that a wheatstone bridge circuit is used to do this.. but I don't understand why I can't just use a milliammeter to measure the change in current through the strain gauge and then use R=V/I to find the new resistance/change in resistance. Sorry if it's a stupid question, but could someone please explain why a wheatstone bridge is used?

thanks.
 
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From Wikipedia:
Even with strain gauges that are not self-temperature compensated (such as isoelastic alloy), using a Wheatstone bridge arrangement it is possible to compensate for temperature changes in the specimen under test and the strain gauge. To do this in a Wheatstone bridge made of four gauges, two gauges are attached to the specimen, and two are left unattached, unstrained, and at the same temperature as the specimen and the attached gauges
 
so you are saying the only reason to use a wheatstone bridge is to remove the effect of temperature?
In my experiment, I need to measure how the resistance of a strain gauge varies with changes to the temperature of the specimen material, so does this mean I do not need to use a wheatstone bridge?
 
anyone? :z
 
i need help on this one aswell...have u started yet
 

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