conductor will create a voltage drop along the cable ground of IR, so the destination end of the ground conductor will be at a different potential than the source end Since the differential amplifier has high impedance, little current flows in the signal wire, therefore there is no voltage drop across it: The ground voltage appears to be in series with the signal voltage V1 and adds to it If I is an AC current this can result in noise added to the signal path in component 2. Sources of ground current The diagrams in this section show a typical ground loop caused by a signal cable S connecting two grounded electronic components C1 and C2. The loop consists of the signal cable's ground conductor, which is connected through the components' metal chassis to the ground wires P in their power cords, which are plugged into outlet grounds which are connected through the building's utility ground wire system G. Such loops in the ground path can cause currents in signal cable grounds by two main mechanisms: Ground loop currents can be induced by stray AC magnetic fields (B, green) which are always present around AC electrical wiring. The ground loop constitutes a conductive wire loop which may have a large area of several square meters. According to Faraday's law of induction, any time-varying magnetic flux passing through the loop induces an electromotive force (EMF) in the loop, causing a time varying current to flow. The loop acts like a short circuited single-turn transformer winding; any AC magnetic flux from nearby transformers, electric motors, or just adjacent power wiring, will induce AC currents in the loop by induction. In general, the larger the area spanned by the loop and the larger the magnetic flux through it, the larger the induced currents will be. Since its resistance is typically very low, often less than 1 ohm, the induced currents can be large. Another less common source of ground loop currents, particularly in high-power equipment, is current leaking from the hot side of the power line into the ground system. In addition to resistive leakage, current can also be induced through low impedance capacitive or inductive coupling. The ground potential at different outlets may differ by as much as 10 to 20 volts due to voltage drops from these currents. The diagram shows leakage current from an appliance such as an electric motor