## Bilateral Network:

• A circuit whose characteristics, behaviour are the same independent of the direction of current through various elements of it, is called bilateral network.
• A network consisting only resistances is a good example of a bilateral network.
• The bilateral circuit allows the current flow in both directions. A transmission line is the main example of the bilateral circuit.

### Unilateral Network:

• A circuit whose operation, behaviour is dependent on the direction of the current through various elements is called unilateral network.
• Circuit consisting diodes, which allows the flow of current only in one direction is a good example of the unilateral circuit.
• Unilateral circuit allows the current flow only in one direction. Diode rectifier is the main example of the unilateral circuit.

### Classification of Networks

The behaviour of the total network depends upon the behaviour and characteristics of the elements.

#### Linear Network:

A circuit or network whose parameters i.e., elements like capacitances, resistances and inductances are always constant irrespective of the change in voltage, time and temperature, etc. are known as a linear network. The Ohm’s law can be applied to such a network.

#### Nonlinear network:

A circuit whose parameters changes their values with a change in time, voltage, temperature, etc. is known as a non-linear network. The Ohm’s law may not be applied to such network. Such network does not follow the law of superposition. The best example is a circuit consisting of a diode where the diode current does not vary linearly with the voltage applied to it.

### Classification of Components

#### Active Components:

Those devices or components which required an external source to their operation is called Active Components. For Example: Diode, Transistors, and SCR etc.

#### Passive Components:

Those devices or components which do not require external source to their operation is called Passive Components. For Example: Resistor, Capacitor, Inductor etc.

### Electric Circuit

The interconnection of different Electrical Circuit Elements is arranged in a manner to form a closed path is called an electric circuit.

#### Types of Electric Circuit

The electric circuit can be classified into three types
• Open circuit.
• Short circuit
• Closed circuit

#### Open Circuit

The open circuit means disconnection of any part of an electric circuit if there is no current flow in the circuit is said to be open circuited. Resistance of open circuit is infinity (ideally) or very high (practically).

#### Short Circuit

An electrical circuit in a device of lower resistance/zero resistance than that of a normal circuit. Resistance of short circuit is zero (ideally) or very low (practically).

#### Closed Circuit

The closed circuit means there is no break or discontinuity in the circuit and current flow from one part to another part of the circuit, then the circuit is called as a closed circuit.

### Series circuit and parallel circuit.

#### Series Circuit

When all elements of a circuit are connected one by one in tail to head fashion and due to which there will be only one path of flowing current in the circuit is called as series circuit. The circuit elements are said to be series connected. In series circuit same current flows through all elements connected in series.

#### Parallel Circuit

If components are connected in such a way that the voltage drop across each component is same is called as parallel circuit. In parallel circuit the voltage drop across each component is same but the current flow is different in each component. The total current is the sum of currents flowing through each element.

#### Basic Properties of Electric Circuits:

• A circuit is always a closed path.
• A circuit always contains an energy source which acts as a source of electrons.
• Direction of flow of conventional current is from positive to negative terminal.
• The electric elements include uncontrolled and controlled source of energy, resistors, capacitors, inductors, etc.
• Flow of current leads to potential drop across the various elements.
• In an electric circuit flow of electrons takes place from the negative terminal to the positive terminal.

### Types of sources:

#### Properties of current source:

•  Constant current flows through current source.
•  Current remains same in series.
• Internal resistance of ideal current source is infinity ohm.

#### Properties of Voltage source:

• Constant voltage is available across DC voltage source.
• Voltage remains same in parallel.
• Internal resistance of ideal voltage source is zero ohm