Source Transformation

By analyzing the materials about Thevenin's theorem and Norton's theorem, it can be easily concluded that they are equivalent - the current and voltage in branch AB must be the same in both cases

As can be seen, a series branch containing a voltage source E and impedance Z can be replaced by a parallel branch containing a current source I and impedance Z without changing the current in the external circuit. The value of impedance in both cases is the same, and the relationship between current and voltage is:

\begin{aligned} I=\frac{U}{Z} \longleftrightarrow U=Z\cdot I \end{aligned}

As can be easily noticed from the above, it is possible to both transform a current source into a voltage source and transform a voltage source into a current source.