Superposition is a method that can be used to analyze linear electric circuits. The method is based on the fact that the values of the potentials and currents in a circuit containing multiple independent sources can be calculated by adding algebraically the potentials and currents obtained by activating one source at a time.

Assume we have a circuit that contains at least two independent sources.

Step 1. Keep only one independent sources and deactivate all the other independent sources. Notice that if you circuit contains dependent sources you need to keep those in the circuit (in a way, they are treated like resistors).

Step 2. Calculate the potentials and currents in the circuit.

Step 3. Repeat the last two steps for each source in the circuit.

Step 4. Superimpose the values of potentials and currents obtained at Step 2; pay special attention to the direction of the voltage drops and current flows.

• To deactivate a current source we remove it from the circuit (replace it with open-circuit or break); to deactivate a voltage source we replace it with a short-circuit (or wire).
• Unlike mesh and nodal analysis that can be applied to both nonlinear and linear circuits, superposition can be applied only to linear circuits. Therefore, we cannot use superposition to compute the potential and currents in a circuit containing diodes, transistors, or other nonlinear elements.
• The superposition method can be applied to DC, AC and time-dependent circuits (as long as the circuit is linear).
• The superposition method cannot be used to add power. If we need to compute the power generated or dissipated by a component, we need to compute the voltage across and current flowing through the component first and, then, the power.

• DC analysis (analytical)
  DC circuit with 2 sources
  DC circuit with 3 sources
  
• DC analysis (numerical)
  DC circuit with 2 sources
  DC circuit with 3 sources