Why should we modify the voltage source value if the resistor is connected with it directly?i mean,there are two different circuit below ,and their corresponding equivalent circuit.
As we can see,after equivalizing these circuit,we don't modify the voltage source of the first circuit,but we do modify the voltage source of the second circuit.i want to ask why,why should we modify the voltage source value if the resistor is connected with it directly?
This problem is about determining the Thevenin equivalent of a voltage source with some external resistors.
In general, the Thevenin voltage will be the open-circuit voltage of the network you're simplifying.
In the first case, the open-circuit voltage is exactly equal to the original source voltage, because the output terminals are directly across the source.
In the second case, the open-circuit voltage is less than the original source voltage because the output is taken by a voltage divider formed from R4 and R1.
