Question

Consider the op-amp circuit shown in the figure below:


The value of output voltage $V_0$ is equal to ____V.

• A. 55

Answer 1

The correct option is A 55
Applying KCL at node $V^{+}$, we get,
$\frac{V^{+}-10}{60k\Omega }+\frac{V^{+}-15}{20k\Omega }+\frac{V^{+}}{30k\Omega }=0$



$\therefore \frac{V^{+}}{10k\Omega }=\frac{1}{6k\Omega }+\frac{3}{4k\Omega }$
$\therefore V^{+}=\frac{55}{6}$
$\therefore V_0=(1+\frac{R_2}{R_1})V^{+}=(1+5)\times \frac{55}{6}$
$V_0=55V$