what is virtual ground in op amp

A virtual ground in an op amp is a node of a circuit that is maintained at a steady reference potential, without being connected directly to the reference potential. It is a concept that is very useful in the analysis of op amp circuits and simplifies many calculations. The term virtual ground means that the voltage at that particular node is almost equal to ground voltage (0V), but it is not physically connected to ground. The virtual ground concept is employed in inverting amplifiers, where the voltage at the inverting input terminal is equal to the voltage at the grounded non-inverting input terminal. This is possible because of the high open-loop gain of the op amp, which tends to infinity, and the negative feedback. The virtual ground concept is useful for gain calculation and provides practical circuit effects that would be difficult to achieve in other ways. An active virtual ground circuit is sometimes called a rail splitter.