Why do we turn of all the independent sources in order to find thevenin equivalent?

Question

anonymous · Answer

We do this to calculate thevenin equivalent resistance calculation. Actually thevenin equivalent resistance is nothing but output resistance of thevenin equivalent voltage source. We remove our load and find voltage at load ends due to other sources in circuit then what output resistance this voltage or equivalent voltage source will offer to load. AS WE HAVE ALREADY INCLUDED THE IMPACT OF OTHER VOLTAGE/CURRENT SOURCES IN THE CIRCUIT, now from load terminal ends to find what is equivalent resistance there just pretend you have connected a voltage source there and  make other sources to zero.THIS IS NOT TRUE ONLY WHILE USING THEVENIN THEOREM, BUT ALSO TO CALCULATE OUTPUT IMPEDANCE/ RESISTANCE OF OTHER ACTIVE DEVICES LIKE MOSFET, BJT ETC.