Question

Strain gauge $G_f=2$ and operational amplifier $A_d=2500,A_c=0.25$. For given quarter Wheatstone bridge the strain is

• A. $100\mu$
• B. $300\mu$
• C. $400\mu$
• D. $200\mu$

Answer 1

The correct option is D $200\mu$

$\text{When no strain,}{V}_1=V_2=6V$

$\text{Output voltage,}$

$\Rightarrow 4.5=2500(V_1-V_2)+(6\times 0.25)$

$\Rightarrow (V_1-V_2)=1.2\times {10}^{-3}$

$\Rightarrow 1.2\times {10}^{-3}=\frac{2\times \epsilon \times 12}{4}$

$\therefore \epsilon =200\mu \text{strain}$