physics of inductance and capacitance..discussion

[azaz104]

Hi everyone,

I would like to know how did they invent the capacitor, inductor...

what are the mIcroscopic theory of these element...not as all the books do the mAcroscopic analysis....

are there any articles, discussions or books explaining the atomic behaviour of the materials.....

hope i can open a discussion on this issue.

and by the way, do Feynman lectures contain anything about this?

 

[jakyshan1990]

i read some that capacitors by foils in ASIC
these part from RFID handbook

Modern systems employ coils etched between foils in the form of
stick-on labels. To ensure that the damping resistance does not become too high and
reduce the quality of the resonant circuit to an unacceptable level, the thickness of

the aluminium conduction tracks on the 25 μm thick polyethylene foil must be at least
50μm (J¨orn, 1994). Intermediate foils of 10μm thickness are used to manufacture the
capacitor plates.

 

[albbg]

Invention of the capacitor started with the so called "Leyden Jar", please refer to Leyden jar - Wikipedia, the free encyclopedia.
Doing a very simplified microscopic analysis, the molecules of the dielectric (made by non-conductor material) are subjected to the electric filed between the two plates. Since there are not full mobile charges (as instead in conductors) but only some charge displacement is allowed, these will be oriented according the charge of each plate. Removing the voltage applied to the plates, the orientation in the dielectric is still retained so you can remove (if you want to prove that the charges are stored in the dielectric) the dielectric from the plates. When you will put againg the dielectric between the plates the electric field is restored and you will measure at the plates the same voltage (ideally) you used to charge the capacitor.
I hope it can help, even if probably I was not very understandable

 

[BradtheRad]

In my youth a buddy of mine was into electronics. (I'd had a course in basic electricity.)

He once showed me two large squares of aluminum foil separated by a piece of glass.

He hooked up house current across them. Current was flowing.

However there was no direct connection to allow current to flow.

I didn't see how it was possible. I had been taught electricity needed a complete circuit in order to flow.

However he said it was a 'capacitor'.

He slid the foil squares apart so they didn't overlap as much. Current flow went down.

Then he slid them back to maximum overlap. Current flow went up.

It took me a long time to catch on to what he was showing me.