Final answer:
To determine the Thevenin equivalent circuit, we short a specific resistor in the original circuit. The resistor to short depends on the goal or question at hand.
Step-by-step explanation:
In Thevenin's theorem, to determine the equivalent resistance and voltage source of a complex circuit, we need to short one resistor in the original circuit. The resistor to short is the one for which we want to determine its effect on the Thevenin equivalent circuit. By shorting a resistor, we are effectively removing it from the circuit, which allows us to calculate the equivalent resistance and voltage source using the remaining components. The specific resistor that should be shorted depends on the goal or question at hand.
For example, if we want to find the Thevenin resistance (or output resistance), we need to short the independent voltage (or current) sources and measure the resulting resistance across the load. If we want to find the Thevenin voltage (or output voltage), we need to short the current sources and measure the resulting voltage across the load. Selecting the resistor to short depends on the specific information or parameter we are trying to determine in the Thevenin equivalent circuit.