Nortonyhtälöt

Nortonyhtälöt, also known as Norton's equations, are a fundamental concept in electrical circuit analysis. They provide a way to simplify complex circuits by representing them with equivalent circuits consisting of a single voltage source in series with a single resistor or a single current source in series with a single resistor. Specifically, the Norton equivalent circuit consists of a current source in parallel with a resistor.

The Norton equivalent current, often denoted as $I_N$, represents the short-circuit current that flows through the terminals of the original circuit when they are connected together. The Norton equivalent resistance, $R_N$, is the equivalent resistance of the circuit as seen from the terminals, with all independent sources turned off. This means voltage sources are replaced by short circuits and current sources by open circuits.

The relationship between the Norton equivalent circuit and the original circuit is such that when a load is connected across the terminals, the current and voltage across the load will be the same for both the original circuit and its Norton equivalent. This simplification is particularly useful when analyzing the behavior of a circuit with varying loads, as the complex original circuit can be replaced by a much simpler Norton equivalent for each load scenario. The Norton equivalent is closely related to the Thevenin equivalent circuit; they can be converted into each other. The Norton equivalent current $I_N$ is equal to the Thevenin equivalent voltage $V_{Th}$ divided by the Thevenin equivalent resistance $R_{Th}$ (which is also equal to $R_N$), and the Norton equivalent resistance $R_N$ is equal to the Thevenin equivalent resistance $R_{Th}$.