's theorem, an electrical circuit is simplified into an equivalent circuit that consists of a single voltage source and a single resistor. The voltage source represents the open-circuit voltage of the original circuit, while the resistor represents the equivalent resistance of the original circuit as seen from the two terminals where the voltage source is connected.

Thevenin's theorem is often used to simplify complex circuits into simpler ones that are easier to analyze. By finding the Thevenin equivalent circuit of a circuit, one can determine the voltage and current at any point in the circuit with less effort than analyzing the original circuit. This can be particularly useful in designing and troubleshooting electrical circuits.

The Thevenin equivalent circuit is determined by first finding the open-circuit voltage of the original circuit, which is the voltage between the two terminals where the equivalent circuit will be connected. The equivalent resistance is then found by replacing all sources in the circuit with their internal resistances and calculating the resistance seen from the two terminals. The voltage source is then placed in series with the equivalent resistance, and the resulting circuit is the Thevenin equivalent circuit.

In summary, Thevenin's theorem states that any linear, bilateral network consisting of voltage and current sources and resistors can be replaced by an equivalent circuit consisting of a single voltage source and a single resistor. This simplification can be very useful in circuit analysis and design.

Any linear circuit containing several voltages and resistances can be replaced by just one single voltage in series with a single resistance connected across the load.