Question about using a wheatstone bridge to measure changes in resistance

AI Thread Summary
A Wheatstone bridge is preferred for measuring small changes in resistance, such as those from a strain gauge, because it provides higher sensitivity and accuracy compared to a simple milliammeter setup. It compensates for temperature variations, allowing for more precise measurements by using a balanced circuit with both strained and unstrained gauges. While measuring resistance changes directly with a milliammeter is possible, it may not account for external factors that can affect readings. In experiments where temperature changes are significant, a Wheatstone bridge can help isolate the strain gauge's response from temperature effects. Therefore, using a Wheatstone bridge is beneficial for accurate resistance measurements in varying conditions.
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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