Question

Is superposition theorem valid for AC or DC?

Answer 1

The Superposition Theorem is valid for both AC (Alternating Current) and DC (Direct Current) circuits. However, the way it is applied differs slightly between the two types of circuits.

### For DC Circuits:
The Superposition Theorem can be applied directly. In a DC circuit, you treat each independent source (voltage or current) one at a time. You "turn off" all other sources (replace voltage sources with short circuits and current sources with open circuits) and calculate the response (voltage or current) due to the remaining active source. Afterward, you repeat the process for each independent source, and the total response is the sum of all individual responses.

### For AC Circuits:
In AC circuits, the Superposition Theorem works similarly, but you must consider the sources in terms of their frequency, phase, and impedance. Each independent AC source is handled one at a time, treating other sources as inactive. When you calculate the response due to each source, you keep in mind the sinusoidal nature (amplitude and phase) of the voltages or currents. Once you've calculated the individual responses, you add them together, ensuring you correctly combine the amplitudes and phases of the AC signals.

So, **Superposition Theorem is valid for both AC and DC**, but in AC circuits, you must also take into account the complex relationships (magnitude and phase) between the voltages and currents.