Electrical Networks and Circuits

Summary

Electrical networks are interconnections of electrical components such as voltage sources, current sources, resistors, capacitors, inductors, switches, and transistors. An electrical circuit is a network with a closed loop that provides a return path for current, while a network without a closed loop is commonly called an open circuit. Networks may be resistive, containing only resistors and ideal sources, or may include reactive components such as capacitors and inductors. Networks containing active electronic components are generally nonlinear and require more advanced analysis methods. Electrical networks can be classified by passivity, linearity, and lumpiness. Active networks contain sources capable of supplying energy, whereas passive networks contain only passive elements. Linear networks obey superposition and can be analyzed using methods such as frequency-domain techniques, while nonlinear networks often require numerical simulation or approximation. Circuit behavior is determined using Ohm’s law, Kirchhoff’s current and voltage laws, Thévenin’s theorem, Norton’s theorem, and the superposition theorem. Complex circuits are commonly analyzed with software such as SPICE, using methods including steady-state analysis, linearization around an operating point, and piecewise-linear approximation.

Key Points

• 1

  An electrical circuit is a closed-loop electrical network, but not every electrical network contains a closed loop.

• 2

  Networks may be active or passive, linear or nonlinear, and lumped-element or distributed-element designs.

• 3

  Ohm’s law, Kirchhoff’s laws, Thévenin’s theorem, Norton’s theorem, and the superposition theorem are fundamental tools for circuit analysis.

• 4

  Complex circuits can be analyzed and simulated using software such as SPICE, including linearized and piecewise-linear models.