# 3DGURU's Class : Physics

Hi , i liked the concept of studying on the painting tablet , here goes a solved example , this way learns faster and longer than on notebooks , …

i’m certain that i will need help , can i ask you when there’s Questions :rolleyes: ? , we are studying
Physics for Scientists and Engingers with modern physics , 6th edition

Ah, there’s a reason I didn’t become an electrical engineer… :spin:

… lol dude you will be an awesome engineer since you already write like one!

Ooo physics!

I’d love to see your questions. Hopefully I’d be able to figure them out…

-Laurifer

is the Electric field zero in this case ?

Ha! I’m an electric engineer and I’m happy to say that I forgot everything 2 years after getting my diploma.
But to answer your question: The inside of any conductor has no electric field (cage of Faraday). So, electric current would only exist on the outside of a wire. For all we care, a wire could be perfectly hollow. So, why there is less resistance if the diameter of the wire is bigger? Well the diameter is directly related to the area of the wire.

But like I said, it’s a long time ago for me. I don’t even know the Bode formula for a P.I.D. regulation by heart, or what the Fermi level in semi conductors is…

does it make any difference if the cylinder was conducting or insulating ? copper or rubber ?
what does the cage of farady is releated to this? , never heared of it anyway .
thanks

That is complicated indeed! I think copper texture is reall cool in Blender.

A Faraday cage is a structure built out of conducting wire (a mesh, although I guess it could probably be solid, not sure, or even a wire itself) that basically “deflects” for a lack of better wording electric fields. That is, it isolates the field on the inside of the cage from the one on the outside.

For instance, if you put a cell phone or radio in a perfect Faraday cage it would cease to work since they rely on electric fields in the air to work. This explains why when your in older buildings (or buildings with lots of copper plumbing) your cell phone reception is lower than when its outside. Essentially the copper piping is insulating you from the electric fields (radio signals) needed by your cell phone to communicate with the base towers by causing the charges to accumulate on their surface.

The charges essentially realign on the Faraday cage so that they cancel the charges on the inside.