Question

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

The value of output voltage $V_0$ is equal to

• A. $-\frac{V_1}{2}$
• B. $2V_1$
• C. $4V_1$
• D. $0$

Answer 1

The correct option is A $-\frac{V_1}{2}$

By applying superposition theorem, we get,

When$V_1$ at non-inverting terminal is shorted

$V_{01}=-\frac{40}{20}{V}_1=-2V_1$ .... (i)

When $V_1$ at inverting terminal is shorted , then

$V_{02}=[1+\frac{40}{20}]\times \left[\frac{30}{30+30}\right]V_1=3\times \frac{3}{6}{V}_1=1.5V_1$ …. (ii)

Combining equation (i) and (ii) , we get ,

$V_0=V_{01}+V_{02}=-2V_1+1.5V_1$

$=-\frac{V_1}{2}$