Question

With zero volts on both inputs, an OP-amp ideally should have an output .
A. Equal to the positive supply voltage
B. Equal to the negative supply voltage
C. Equal to zero
D. Equal to infinity

Answer 1

Hint: An OP-amp is a voltage amplifying electronic device which is used with external feedback components like resistance and capacitor between its output and input terminals. An OP-amp is based on the concept of differential amplifier.
A differential amplifier only amplifies the difference of input voltage. It cannot amplify common mode input voltage.

Complete step by step answer:
An OP-amp is a voltage amplifying electronic device which is used with external feedback components like resistance and capacitor between its output and input terminals. An OP-amp is based on the concept of differential amplifier.

Op amps are used in a variety of applications in electronics. Some of the common applications are: as a voltage follower, inverting OP-amp, a current-to-voltage converter, active rectifier, integrator, a whole wide variety of filters, and a voltage comparator.
A differential amplifier only amplifies the difference of input voltage. It cannot amplify common mode input voltage. Mathematically, output voltage of an ideal op-amp
${{V}_{o}}=A{{V}_{d}}$
Where $A$ is the open loop gain of op-amp and ${{V}_{d}}$ is the difference input voltage.
Since, the difference in input voltage on both inputs is zero. Therefore, output of an ideal op-amp is also zero.

So, the correct answer is “Option C”.

Note: An OP-amp is based on the concept of differential amplifier. A differential amplifier only amplifies the difference of input voltage. It cannot amplify common mode input voltage.
Open loop gain and input impedance of an ideal op-amp is infinite.