# 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).

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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

by (39.8k points)
The accurate answer is (b) 0.8Ω

Embark on a journey of understanding with: The output voltage of analog weight scale, Vo = Vdc×(△R/R)×(RF/R1)

=> △R=( Vo/ Vdc)×(R1/RF)×R =( 5v×200Ω)/(125×10v) =0.8Ω.

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