The gain of the differential amplifier is -125. Assume the voltage applied to bridge circuit Vdc=+10v and the unstrained resistance of four element of strain gage is 200Ω. When a certain weight is placed on the platform, the output voltage Vo=5v. Determine the change in resistance of each strain gage for analog weight scale. (Assuming the output is initially nulled).

(a) 1Ω

(b) 0.8Ω

(c) 0.3Ω

(d) 1.83Ω

I have been asked this question in an online quiz.

My question is based upon High Frequency Op-Amp Equivalent Circuit in chapter Operational Amplifier Applications of Linear Integrated Circuits