Classification of Electrical Network

Summary

In this video, the presenter explains the classification of electrical networks, dividing them into five categories based on circuit properties and network response to different excitations. The first three types—active vs. passive, unilateral vs. bilateral, and lumped vs. distributed networks—focus on the characteristics of the elements in the network. The last two types—linear vs. non-linear, and time-invariant vs. time-variant networks—are based on the network's behavior and response. This educational breakdown helps viewers understand how different networks function and their real-world applications in electronics.

Takeaways

• 😀 Electrical networks can be broadly classified into 5 categories based on properties of circuit elements and network response to excitations.
• 😀 Active elements, such as voltage and current sources, deliver energy to external devices, whereas passive elements, like resistors, capacitors, and inductors, receive or store energy.
• 😀 An active network contains elements like voltage or current sources, which can deliver energy indefinitely, unlike passive elements which can only deliver energy for a limited time.
• 😀 Bilateral elements allow current to flow in both directions, such as resistors, capacitors, and inductors, while unilateral elements like diodes and transistors allow current flow in only one direction.
• 😀 A unilateral network contains elements that restrict current flow to one direction, like rectifier circuits using diodes.
• 😀 Lumped networks feature discrete circuit elements that can be separated and measured, whereas distributed networks involve elements that act as a continuous entity along the length of the network, such as transmission lines.
• 😀 Linear networks exhibit a linear relationship between input and output, and follow the principle of superposition (i.e., the output is a direct sum of individual responses to inputs).
• 😀 The property of homogeneity in linear networks means that scaling the input by a factor will scale the output by the same factor.
• 😀 The property of additivity in linear networks means that the output response to combined inputs is the sum of individual responses.
• 😀 Time-invariant networks produce the same output response regardless of when the excitation is applied, while time-variant networks have responses that change depending on when the excitation is applied.

Q & A

What are the two main factors that classify electrical networks?

The classification of electrical networks is based on two factors: the properties of the circuit elements connected in the network and the response of the network to different excitations.

What distinguishes active and passive elements in electrical networks?

Active elements are capable of delivering energy to external devices (e.g., voltage and current sources), while passive elements receive energy or power, like resistors, capacitors, and inductors. Passive elements store energy temporarily, whereas active elements can deliver energy indefinitely.

How does an active network differ from a passive network?

An active network contains elements like voltage or current sources that can deliver energy indefinitely, while a passive network consists of elements like resistors, capacitors, and inductors, which can only store or dissipate energy temporarily.

What is the difference between unilateral and bilateral networks?

In bilateral networks, current can flow in both directions through elements like resistors, capacitors, and inductors. In unilateral networks, current flows in only one direction, as seen in elements like diodes and transistors.

What is an example of a unilateral network?

An example of a unilateral network is a rectifier circuit, where elements like diodes allow current to flow in one direction only.

What distinguishes lumped networks from distributed networks?

In lumped networks, elements like resistors, capacitors, and inductors are treated as discrete components that can be separated physically. In distributed networks, like transmission lines or coaxial cables, circuit elements are distributed along the length of the network and cannot be separated in the same way.

What is meant by a linear network?

A linear network is one in which the relationship between input and output is linear, meaning it satisfies the principles of superposition, homogeneity, and additivity.

What are the properties of homogeneity and additivity in linear networks?

Homogeneity means that if the input is scaled by a factor, the output will scale by the same factor. Additivity means that if two inputs are applied separately and their outputs are obtained, applying the sum of the inputs should yield the sum of the outputs.

What is the principle of superposition in the context of linear networks?

The principle of superposition states that in a linear network, the response to multiple inputs can be found by adding the individual responses to each input applied separately. This principle applies when the network is linear.

What is the difference between time-invariant and time-variant networks?

In time-invariant networks, the response remains the same regardless of when an excitation is applied. In time-variant networks, the response depends on the time at which the excitation is applied, meaning the response can change over time.