Question

Consider the opamp circuit shown in figure below,

The value of input resistance $R_{in}$ of the circuit will be

• A. 5 $k\Omega$
• B. 8 $k\Omega$
• C. $\frac{15}{8}k\Omega$
• D. 10 $k\Omega$

Answer 1

The correct option is A 5 $k\Omega$

Since, $V_1=V_2=0V$ ( By Virtual ground concept )
So , 3 $k\Omega$ resistance is redundant

$\therefore$ The input resistance is 5 $k\Omega$