Electrical elements and circuits

Рет қаралды 46,170

Күн бұрын

Пікірлер: 9

@williamking595 6 жыл бұрын

You're a very good instructor. I'm just now getting into electric and mechanical engineering (I'm a programmer) and so far, your videos have been quite easy to follow. I plan on going through the entire series and learning as much as possible. Good job!

@sridharchitta7321 3 жыл бұрын

"The voltage across a capacitor cannot change instantaneously" is a statement one finds often in textbooks on circuit theory which discuss the application of a step voltage to an RC circuit. Most students memorise and apply this in circuits without understanding the physical processes involved. It is not possible in this post to discuss the charging of an uncharged capacitor. During the first few nanoseconds after switch ON, while the surface charges arrange themselves, there is no electric field E_cap and fringe field because there is no initial charge on its plates; it is as though the capacitor was not there - as though there were a continuous wire with no break in it. To understand this intuitively it is useful to know what is a fringe field of capacitors and what its effect is at different frequencies. It is not possible in this post to discuss the charging of an uncharged capacitor. During the first few nanoseconds after switch ON, while the surface charges arrange themselves, there is no electric field E_cap and fringe field because there is no initial charge on its plates; it is as though the capacitor was not there - as though there were a continuous wire with no break in it. While it is not possible to describe in detail the association of non-Conservative fields with time-varying magnetic fields as in inductors, this maybe the cause of confusion of stating "voltage in an inductor appears only across the terminals, not along the inductor". The non-Conservative electric field polarizes the inductor and results in surface charge production which produces a Coulomb electric field. It would be instructive to understand Current and the conduction process using a unified approach to electrostatics and circuits as in the two videos below before understanding voltage across inductors. 1. kzbin.info/www/bejne/ioXXpWVul5aXj9E 2. kzbin.info/www/bejne/bnO0fpKurJeFnNE How does phase shift occur in a single inductor? What happens if a resistor were to be included? Classical analysis does not provide answers to these questions in an intuitive way. To understand the reason for phase shift in inductive circuits Faraday's law should be applied. This can explain the co-occurrence of a non-Coulomb electric field with a changing current in the inductor. Also, a Coulomb electric field appears and this is hard to explain unless one takes a unified approach to electrostatics and circuits. Knowing this will help in understanding the operation of RL and RC circuits as filters. Attenuation, it should be understood, denotes a decrease of the amplitude, or magnitude of coherent or incoherent electromagnetic waves or electrical impulses without specifying what quantity should be used to measure the decrease, whether the decrease should be space-dependent, time-dependent or both, the cause of the decrease or, the conditions under which the decrease is to be measured. A resistor can produce attenuation but it need not be there always to produce attenuation. Lossless lines and T-section and m-derived section filters can attenuate signals as well. The textbooks 3 and 4 listed under References in the last frame of video #1 discuss the topics on inductors and voltages in them in more detail.