Electric Circuits I (EELE 2310)

Electric Power Engineering site.iugaza.edu.ps/ajasser Assad Abu-Jasser, PhD Electric Power Engineering site.iugaza.edu.ps/ajasser ajasser@iugaza.edu.ps

Chapter Two Circuit Elements

Electric Sources Voltage and Current Sources Electrical Source is a device that is capable of converting nonelectric energy to electric energy and vice versa An Ideal Voltage Source is a circuit element that maintains a prescribed voltage across its terminals regardless of the current flowing in those terminals An Ideal Current Source is a circuit element that maintains a prescribed current through its terminals regardless of the voltage across those terminals

Voltage and Current Sources Independent Sources An Independent Source establishes a voltage or current in a circuit without relying on voltages or currents elsewhere in the circuit

Voltage and Current Sources Dependent Sources A dependent Source (Controlled Source) establishes a voltage or current whose value depends on the value of a voltage or a current elsewhere in the circuit μ, ρ, α, and β are multiplying constants Active Elements capable of generating electric energy Passive Elements cannot generate electric energy

Example 2.1 Valid Invalid Valid Valid Invalid Using the definition of the ideal independent voltage and current sources, state which interconnections in the following figures are permissible and which violate the constraints imposed by the ideal sources Valid Invalid Valid Valid Invalid

Example 2.2 Invalid Valid Valid Invalid Using the definition of the ideal independent and dependent sources, state which interconnections in the following figures are valid and which violate the constraints imposed by the ideal sources Invalid Valid Valid Invalid

Electrical Resistance Ohm’s Law

Example 2.3 In each of the following circuits υ or i is not known. (a) Calculate the value of υ or i, (b) Determine the power dissipated in each resistor. 8 V -20 V 10 A -2 A

Example 2.4 Constructing A Circuit Model

Example 2.5 The voltage and the current are measured at the terminals of the device in the figure shown and the values are tabulated as given. Construct a circuit model of the device inside the box.

Kirchhoff’s Laws Kirchhoff’s Current Law 7 Unknowns The algebraic sum of all currents at any node in a circuit equals zero

Kirchhoff’s Laws Kirchhoff’s Voltage Law The algebraic sum of all voltages around any closed path in a circuit equals zero

Example 2.6 Sum the currents at each node in the circuit shown. Note that there is no connection dot (●) in the center of the diagram.

Example 2.7 Sum the voltages around each designated path in the circuit shown.

Example 2.8 Use Kirchhoff’s laws and Ohm’s law to find io in the circuit shown and test the solution for io by verifying that the total power generated equals the total power dissipated.

Example 2.9 The terminal voltage and the terminal current were measured on the device shown in the figure shown and the values are tabulated. (a) construct a circuit model of the device inside the box, (b) using the circuit model, predict the power this device will deliver to a 10 Ω resistor.

Analysis of Circuits Containing Dependent Sources

Example 2.10 Use Kirchhoff’s laws and Ohm’s law to find the voltage υo in the circuit shown and test the solution by verifying that the total power developed equals the total power dissipated.

Practical Perspective Electrical Safety

End of Chapter Two