So, I am learning about how strain gauges work and I understand that through stretching or compressing resistance of the staring gauge can be changed which can be measured in resistance accurately connected to a wheat stone bridge or some kind of bridge and the voltage difference is amplified by an op amp.
Okay, so far sounds good.
But with the values of resistance and voltage difference, how do you exactly use this information to calculate the force caused by the strain. I couldnt find where to look for this equation or information in general. Maybe I am asking questions about mechanism too much but was just curious to know exactly how strain gauge could be used to calculate force in a load cell for example.