# Superposition’s theorem

In a linear, bilateral circuit, containing more than one sources, the one sources, the resultant current (or voltage) of any branch is the algebraic sum of the currents (or voltages) that would be produced by each source, acting alone, all other sources being replaced meanwhile by their respective internal resistances.

If the internal resistances R_{se} of any voltage sources and voltages sources and the internal resistances of R_{sh} of any current sources are not given, assume R_{se}=0 and voltage source by a short circuit and assume R_{sh} → ∞ and replace current source by an open circuit.

### Applications and limitations

The superposition’s theorem is applications only to the linear, bilateral circuit where all the resistances are linear i.e where all the resistance values are constant irrespective of the variations of current and voltage in magnitude and direction.

Thus the superposition’s principal is not applications to the circuits containing non-linear, unilateral elements such as diodes, rectifiers, thermistors etc. this theorem is not applicable for the determinations of power in any branch because power is non-linear functions.