The reciprocity theorem states that in a linear bilateral single source circuit, the ratio of excitation to response is constant when the positions of excitation and response are interchanged.
Example on Reciprocity Theorem :
By using current division rule, I = 1.5 A
Now we have to interchange E and I.
Since I is pointed downwards in the given problem.So the positive terminal placed downwards when we interchange.
Since E positive terminal points upwards in the given problem, the current I also points upwards in above diagram when we interchange
By using nodal/mesh analysis, I = 1.5 A
Since in both cases I are equal reciprocity theorem is verified.
