Electric Circuits 1_Chapter 1: Basic Concepts

Electric Circuit

An interconnection of electrical elements.

Charge

An electrical property of the atomic particles of which matter consists, measured in coulombs (C).

Electric Current

The time rate of change of charge, measured in amperes (A).

Direct Current (dc)

A current that remains constant with time.

Alternating Current (ac)

A current that varies sinusoidally with time.

Power

The time rate of expending or absorbing energy, measured in watts (W).

Passive Sign Convention

Satisfied when the current enters through the positive terminal of an element and $p = +vi$. If current enters through the negative terminal, $p = -vi$.

Energy

The capacity to do work, measured in joules (J).

Active Element

An element capable of generating energy (e.g., generators, batteries, operational amplifiers).

Passive Element

An element not capable of generating energy (e.g., resistors, capacitors, inductors).

Ideal Independent Source

An active element that provides a specified voltage or current that is completely independent of other circuit elements.

Ideal Dependent (or Controlled) Source

An active element in which the source quantity is controlled by another voltage or current.