Find Rth in Thevenin Circuits: Use Resistors to Find Voc

[th3plan]

So to find Rth why did they choose these resistors. After choosing those resistors to find Rth , then i must use those resistors and go in a loop to find Voc ?

 

[The Electrician]

What do you mean by "those" resistors? Do you mean the 3 1K resistors that go from node A to node B? They chose them because they are the ones that determine the resistance between node A and B once the current sources have been deleted. Since the 2k resistor has one end not connected to anything, it doesn't have any effect on Rth.

To find Voc, you can use any method of solving the network. If you can determine the currents in each of the 1k resistors, then you can multiply each current by 1000 and add up the voltages across each 1k resistor, taking into account the polarity as you follow the path from node A to node B, to get Voc.

 

[piercas]

In Thevenin circuits, Rth (Thevenin resistance) is the equivalent resistance of the circuit when all the voltage sources are replaced by short circuits and all the current sources are replaced by open circuits. This means that Rth represents the resistance seen by the load in the circuit.

To find Rth, we need to use a specific method called the "resistor method." This method involves replacing all the voltage sources with their internal resistances (if any) and then finding the equivalent resistance of the circuit using techniques such as series and parallel combinations. This is done to simplify the circuit and make it easier to find Rth.

The resistors chosen for this method are typically the ones that are most easily combined using series and parallel combinations. This allows for a simpler and more efficient calculation of Rth. However, any combination of resistors that simplifies the circuit and allows for the calculation of Rth can be used.

Once Rth is found, we can then use the same resistors to find the open-circuit voltage (Voc) of the circuit. This is because, in a Thevenin circuit, Voc is equal to the voltage across the load when it is disconnected from the circuit. Using the same resistors ensures that we are calculating the voltage across the load accurately.

In summary, the choice of resistors used to find Rth in Thevenin circuits is based on simplifying the circuit and making it easier to calculate Rth. These same resistors are then used to find Voc, ensuring an accurate calculation of the open-circuit voltage.