Theorems and laws

Common Terms used in Circuit Theory

• A circuit is a closed conducting path through which an electrical current either flows or is intended to flow. A circuit consists of active and passive elements.
• Parameters are the various elements of an electrical circuit (for example, resistance, capacitance, and inductance).
• Linear circuit – a circuit in which the parameters are constant with time, do not change with voltage or current, and obey Ohm’s law. In a non-linear circuit the parameters change with voltage and current.
• A passive network is a one which contains no source of EMF.
• An active network is a one which contains one or more sources of EMF.
• A bilateral circuit is one whose properties or characteristics are same in either direction of current. Example: the usual transmission line is bilateral.
• A unilateral circuit is that circuit in which properties or characteristics change with the direction of operation. Example: a diode rectifier can rectify only in one direction.
• A Node is a point in a circuit where two or more circuit elements are connected together.
• Branch is a part of a network which lies between two nodes.
• Loop is a closed path in a circuit in which no element or node is encountered more than once.
• Mesh is a loop that contains no other loop within it.