Difference Between Real Ground and Virtual Ground

Electrical Technology

What is the Difference Between Real Ground and Virtual Ground?

Real ground is when a terminal is connected physically to the ground or earth. where as virtual ground is a concept used in Op-Amps in which a node is assumed to have the potential that of the ground terminal.

Virtual Ground

In Negative Feedback configurations, the virtual ground concept is only possible when there are same voltages at both terminals and both terminals should not acts as ground.

In Operation Amplifiers, the virtual ground concept is only applicable in Negative Feedback Configuration. In other words, virtual ground is not applicable in Positive Feedback configurations like schmitt trigger but only in Negative Feedback Op-Amps like inverting and non-inverting amplifiers, voltage follower etc.

As shown in below fig of non-inverting Op-Amp (negative feedback), V₁ is connected to the real ground which has zero potential and current flow to the negative terminal of the supply source. V₂ is connected to the virtual ground point as virtual ground is a point which maintains zero potential and current is passing to other nodes but it would not let pass the current to the negative terminal of the supply source. In short, V₂ don’t sink current as current from V₂ node passes to the “R_f” and V_OUT due to high resistance of “R” in Op-Amp. So the V₂ node is acts as a virtual ground where V₁ is connected to the real ground.

Related Post: What is the Purpose of Ground Wire in Overhead Transmission Lines?

Real Ground

In electric circuits, real ground is a common point with 0 voltage (this is not always the case) and it refers to reference voltage. It is the exact and real connection to the ground or earth point. The concept is same as in grounding and earthing where electrical appliances physically connected to the ground for protection.