Question

What does an operational amplifier (Op-Amp) do in its most basic form?

• A. Amplifies a digital signal
• B. Converts AC to DC
• C. Amplifies the difference in voltage between its input terminals
• D. Converts digital signals to analog signals

Hint:

Remember: Op-Amps don’t care about absolute voltages — just the difference between \( V_+ \) and \( V_- \)!

Answer 1

The Correct Option is C

An operational amplifier (Op-Amp) is a fundamental analog electronic component widely used in signal processing and control systems. In its simplest form, an Op-Amp is a high-gain voltage amplifier that outputs a voltage proportional to the difference between its two input voltages — one connected to the inverting terminal (\(-\)) and the other to the non-inverting terminal (\(+\)).
Mathematically, the output voltage is: \[ V_{\text{out}} = A(V_+ - V_-) \] where \( A \) is the open-loop gain of the amplifier (typically very large). Why other options are incorrect:

• (A) Op-Amps handle analog signals, not digital ones.
• (B) Op-Amps are not used to convert AC to DC; that function is typically handled by rectifiers.
• (D) Op-Amps do not convert digital to analog signals — that’s the role of a DAC (Digital-to-Analog Converter).

Thus, the basic and correct function of an Op-Amp is to amplify the voltage difference between its input terminals.