Recent content by cosmonova

Hello, We all know Ohm's law U=RI, but I would like to know the physical explanation behind the apparition of the potential difference U of the resistance. thank you.

Hi, I would like to know what is the physical interpretation of magnetic reluctance. Also, I would like to know why should the magnetic flux in a magnetic circuit composed of different magnetic materials and subject to a magnetomotor force should be the same? Thank you.

Hi, I would like to know what is the physical interpretation of magnetic reluctance. Also I would like to know why the magnetic flux in a magnetic circuit composed of different magnetic materials should be the same? Thank you.

If I have well understood, in semiconductors under an electric field, the conduction results from conduction band electrons gaining a slight energy from the electric field and going to slightly different energy levels in the conduction band?

ZapperZ, I am sorry.I would like to know exactly how is current generated in a N doped material in the band theory perspective.

But can we say that the "weekly bound" electrons of the conduction band that are accelerated by the electric field are the origin of the current in the band theory? What is the difference in energy between the conduction band energy and the first ionisation energy?

So is the conduction in such material due to electrons (travelling between atoms?) thus changing between energetically close states in the conduction band, or should the electrons be totally unbound to the atoms in order to have an electric current? I am asking this because I want to know if...

How should I picture visually the orbital of an electron in this cristal? I also find it rather difficult to admit than the electron "feels" the potential energy of the far nucleus. What happens visually in terms of the electron orbital when we apply an electric field to the cristal ?

Hello, my question is the following: we know from books on semiconductor physics that the energy levels of the electrons in a pure semiconductor cristal form in fact bands of energy. I was wondering why these energy levels are in the form of bands an not simple distinct energy levels as...

I agree with altered-gravity. It is the best explanation I have been told so far. It should be very difficult to translate into quantum theory, and because of that I will stick for now with this explanation. Thanks again Zapper Z. Anyway, for those interested I have found a nice...

Hi ZapperZ, if the 90 degrees pulse made the Net Magnetization of the bulk equal to zero, I find it difficult to relate it with the classical view where the protons rotate 90 degrees and precess around the propagation axe of the RF wave(because classicly the RF wave is an electromagnetic wave...

Hi, When trying to compare my last visualization of the phenomenon to some explanations given by many textbooks or websites on this matter, I realize that something is not right. And this is confusing me a lot. I will resume these contradictions in the following points: 1- I think that...

Hello again, I think I got the whole picture. Correct me if I am wrong: When we consider a certain bulk of hydrogen atoms in a static magnetic field B, at the temperature T, there are two magnetic spin states for the proton. One along the main field axis and the other orthogonal to this...

Hello again, Okay, I think I understood what resonance is about. What is the physical interpretation of the T1 and T2 time constants usually invoked in texts about MRI? I have read somewhere that they corresponded respectively to “spin lattice” and “spin spin” relaxation times. Could...

thanks a lot for your replies. ZapperZ, what you have mentionned is exactly what my question meant. I am sorry for not taking my time to clarify it . But having mentionned it, I have more related questions: 1- what is the reality of the resonance phenomena, i.e why does the maximal...