Tellegen's theorem is a fundamental principle in electrical circuit theory that relates the power flows within a network or circuit. It states that for any linear, bilateral electrical network, the algebraic sum of the instantaneous powers entering a junction in the network is zero. In other words, the sum of power consumed and generated at any junction or node in the network is always zero.
Mathematically, Tellegen's theorem can be expressed as follows:
Σvi * ii = 0
Where:
Σ represents the sum over all branches connected to the node or junction.
vi is the voltage across the i-th branch.
ii is the current flowing through the i-th branch.
In the context of direct current (d.c.) circuits, Tellegen's theorem still holds true. However, it's important to note that Tellegen's theorem is a mathematical relationship that describes power flows. It doesn't provide insights into solving circuit analysis problems directly. Instead, it's a tool that can be used to verify the accuracy of circuit analysis results and to check if the conservation of power is being satisfied at every node.
When working with d.c. circuits, Tellegen's theorem can be applied by calculating the instantaneous power entering and leaving each junction or node and then ensuring that their algebraic sum is indeed zero. This helps to validate the correctness of your circuit analysis calculations and to catch any mistakes or inconsistencies in your analysis.
To summarize, Tellegen's theorem is a valuable principle in circuit theory that ensures the conservation of power in electrical networks, including d.c. circuits. It's not typically used as a direct solving method but rather as a way to validate the results of circuit analysis.