Circuits Lab Report

The amount of voltage or current delivered to a load (a load can be a machine or another electrical network) connected to a complex, resistive circuit was a large interest of engineers who were determining how much power the load can handle. Before calculating the voltage going through the load, engineers had to calculate the voltages or currents going through the circuit that was powering the load. One method that the engineers used was a circuit reduction method known as the Thevenin theorem. The Thevenin theorem states that a complex circuit consisting of several resistors and voltage sources can be replaced by an equivalent circuit containing a single independent voltage source in series with a resistor.

Circuit Analysis Using Thevenin Theorem

Thevenin's Theorem states that it is possible to simplify any linear circuit, no matter how complex, to an equivalent circuit with just a single voltage source and series resistance connected to a load. The qualification of “linear” is identical to that found in the Superposition Theorem, where all the underlying equations must be linear (no exponents or roots). If we're dealing with passive components (such as resistors, and later, inductors and capacitors), this is true. However, there are some components (especially certain gas-discharge and semiconductor components) which are nonlinear: that is, their opposition to current changes with voltage and/or current. As such, we would call circuits containing these types of components, nonlinear circuits.

Thevenin's Theorem is especially useful in analyzing power systems and other circuits where one particular resistor in the circuit (called the “load” resistor) is subject to change, and re-calculation of the circuit is necessary with each trial value of load resistance, to determine voltage across it and current through it. Let's take another look at our example circuit:

When determining the amount of voltage or current delivered to ...