Lecture 3a -- Terms and Definitions

[@이완구-q7m]

Howdy! Very refreshing point of view over D and E. We introduces D only for free charges, which is manageable and can avoid the complex polarization. Gauss's Law can be described with only E as physicists do. In that case charges are in all forms, i.e. free or bound. We electrical engineers like to use D because we can use free charges over the capacitors.

[@이완구-q7m]

The slides are very compact and good and I enjoyed your presentation. Thank you.

[@empossible1577]

Thank you!

[@fuzzyelectrons]

According to my books, there seems to be a typo at 15:06, it should be B=\mu_0 H + \mu_0 M. Thank you for a very good refresher!

[@empossible1577]

Great question!! I should add some notes about this. M in the notes is called magnetic polarization and is correct as written without the u0 term. The M you are referring to is called magnetization and requires the u0 term to be included. It is an unfortunately reuse of the same variable and the two terms even have essentially the same definition. On wikipedia, they write the magnetic polarization as 'I'. Unfortunately, I use 'I' in the course for electric current. We have run out of letters to use! LOL

[@empossible1577]

I updated the notes and the lecture video. empossible.net/academics/emp3302/

[@fuzzyelectrons]

@@empossible1577 Ha! I didn't know there were two so similar definitions being used. Good to know. Also, quite impressive you have already updated the notes and the video, great work!

[@meghjitmajumder3468]

What is the difference between an insulator and a dielectric? As a result, what's the difference between the Convection Current(Frankly I don't understand it at all!!) & The Displacement Current?

[@empossible1577]

There really is no difference between a dielectric and an insulator. I will add that there exist dielectrics that are partly conductive and we would hesitate to call those insulators. A good dielectric is an insulator. Convection current is the movement of charge due to diffusion. Think of putting a drop of food dye in water and watching it spread out. Conduction current is the movement of charge due to an applied electric field. The field puts a force on the charges that causes them to move.

[@meghjitmajumder3468]

@@empossible1577 Ok, thanks very much for the response, sir!!

[@empossible1577]

@@meghjitmajumder3468 You are welcome!

[@이완구-q7m]

Insulator in conduction point of view, dielectric in capacitive material one.