OP Amp
What is an OP amp?
Hint
An operational amplifier (often op amp or opamp) is usually depicted in circuit diagram problems as a triangle.
An amplifier takes an incoming electronic signal, and outputs a larger version of that same signal. An OP amp (operational amplifier) is a type of amplifier with two inputs (one positive and the other negative), an output, and two power supplies (one a positive voltage, and the other negative). It is usually depicted as a triangle in circuit diagrams.
The word Opamp implies specific properties:
 High gain where ~ $$A=10^5\leftrightarrow 10^6$$
 Used in feedback circuits

Differential inputs (two wire inputs as opposed to single wire)
 $$v_{out}=Gain\times (v^{+}v^{})=A\times v_{in}$$
 The input current is typically zero ( $$i=0)$$
In essence, it is a differential amplifier with really high gain. The Opamp physically is a complex design typically comprised of ~50 transistors, resistors, and sometimes capacitors. However, knowing that input current = 0, and
$$v_{out}=A\times v_{in}$$
, we can solve most circuit problems.
An amplifier takes an incoming electronic signal, and outputs a larger version of that same signal. An OP amp (operational amplifier) is a type of amplifier with two inputs (one positive and the other negative), an output, and two power supplies (one a positive voltage, and the other negative). It is usually depicted as a triangle in circuit diagrams.