A system that evolves over time. Such systems are typically modelled by equations that describe how the states of parts of the system vary with time, according to rules that govern how the various parts affect each other. Often the state is composed of many components and particles, each having a location, speed, and other relevant properties (such as mass or charge), whose behaviour is governed by differential equations. Any electronic circuit can be characterized as a dynamic system, and there are a large number of analyses tailored for different types of circuit. See also Ampere’s law; Kirchhoff’s laws; Maxwell’s Equations.