what is an operational amplifier?

SHRIKANT CRAZYwhat is an operational amplifier

The Operational Amplifier is probably the most versatile Integrated Circuit available.
An operational amplifier is a <a href="https://en.wikipedia.org/wiki/Direct_current" target="_blank" rel="nofollow noopener noreferrer">Direct current - Wikipedia</a>-<a href="https://en.wikipedia.org/wiki/Direct_coupling" target="_blank" rel="nofollow noopener noreferrer">Direct Coupling</a> high-<a href="https://en.wikipedia.org/wiki/Gain" target="_blank" rel="nofollow noopener noreferrer">Gain</a> electronic voltage <a href="https://en.wikipedia.org/wiki/Electronic_amplifier" target="_blank" rel="nofollow noopener noreferrer">Electronic Amplifier</a> with a <a href="https://en.wikipedia.org/wiki/Differential_input" target="_blank" rel="nofollow noopener noreferrer">Differential Input</a> and, usually, a single-ended output.

An operational amplifier ("op-amp") is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. An op-amp produces an output voltage that is typically hundreds of thousands times larger than the voltage difference between its input terminals.
- Wikipedia

OPAMP Circuit Diagram:

In addition, Op-Amp has high input impedance and high output admittance.It does not allow current to flow through it but supplies necessary current at the output to drive another circuit. Hence it can be used in buffer circuits as a gateway. Generally opamps are used with +ve or -ve feedback depending upon the need. The feedback voltage would act in a manner such that input current is made zero.

E.g the above circuit shows an opamp connected in negative feedback.
If Rin = 1 ohm; Rtop = 2 ohms and Vin= 1 V, then Vout = - 2 V.
The ratio between the resistance of the top resistor and the resistor at input end gives the gain of the opamp. Gain = Rtop/Rin

We can also say it as voltage to current converter or comparater

Op-Amp is not Simply Converter or Amplifier with various designs and configuration you can make so many different application from Op-Amp and if there is another Op-Amp in Series then again some other configured application. So for Basic idea what an Op-Amp can do please refer to your Text book you will find lot-of application circuits based on Op-Amp.

Operational amplifiers can be used to perform mathematical operations on voltage signals such as inversion, addition, subtraction, integration, differentiation, and multiplication by a constant. An op-amp produces an output voltage that is typically hundreds of thousands times larger than the voltage difference between its input terminals.

Thanks a lot.
Anthony