Thevenin's Theorem is used to find a particular branch current in a circuit as the resistance of that branch is varied while all other resistances and voltage sources remain constant.
"Any two terminal network containing a number of e.m.f sources and resistances can be replaced by an equivalent series circuit having a voltage source Va in series with a resistnce Ra."
where Va=voltage between two terminals
Ra=Resistance between two terminals
"Any two terminal network containing a number of e.m.f sources and resistances can be replaced by an equivalent series circuit having a voltage source Va in series with a resistnce Ra."
where Va=voltage between two terminals
Ra=Resistance between two terminals
