Solving a Simple Circuit of Three Elements

A simple circuit is solved and power absorbed or supplied by each element is determined. KCL as well as Ohm’s law are used in solving the circuit. positive sign convention is used in determining element powers. It is shown and discussed how a source, here current source, can be neither absorbing or supplying power. It is also mentioned that resistors are passive elements and always absorb power/energy.

Power and Energy Conservation

A circuit with two sources and three two port elements is studied. Some voltages and currents are given. Voltage of the voltage source is unknown. We need to analyze the circuit, find power of other elements and use the energy conservation to determine the power of the voltage source.

Circuit Containing Only Sources

We go through solving a circuit which only containes independent sources: two voltage sources and two current sources. KVL and KCL are used to determine voltages and currents.

Solve By Source Definitions, KCL and KVL

A DC resistive circuit consisting of one voltage source and one current source and three resistors is solved using source definition, KCL and KVL.

Find Voltage Using Voltage Division Rule

Determine voltage across and using voltage division rule. Assume that , , , and Solution: Please note that the voltage division rule cannot be directly applied. This is to say that:

Ideal Independent Sources

The ideal independent voltage and current sources are explained. Their symbols and voltage-current characteristics are presented. It is shown how their definitions can be used to solve problems. Some examples are also provided to clarify their characteristics.

Problem 1-15: Power of Independent Sources

Determining power of independent voltage and current sources. Passive sign and active sign conventions are used to find out which source is supplyingpower and which one is absorbing.

Problem 1-14: Current of A Voltage Source

Two simple circuits are used to demonstrate the characteristic of voltage and current sources. In both cases, the voltage sources are in series with current sources.

Problem 1-12: Using Voltage Sources to Determine Node Voltages

A three-node circuit is solved by using the voltage of voltage sources. The nodal analysis is not used since there are enough voltage sources to determine all node voltages.

Problem 1-2: Power and Conductance of Resistors

Finding power and conductance of resistors from the current and resistance