Recent content by FoxBox

You have a point there about not returning the current. I don't understand what you mean by radiation of energy... The current is steady (no acceleration of charges, so no EM waves?) My teacher gave us the following exercise: A non-magnetic (radius R) wire carries a current I, uniformly...

Strange, my integral diverges... I'll post my entire calculation within in a few days because I'm rather convinced the integral diverges... Quick "proof": within the conductor B is proportional to the distance to the conductor axis. B_in ~ r => B_in^2 ~ r^2 => u ~ r^2 outside the...

Hello all, I'd like to calculate the inductance of a straight current carrying wire per unit length of wire. The wire has radius R. Assume the current is uniformly distributed over the wire's cross section. My approach: The magnetic energy density at every point is given by u = B^2 / (2...

Maybe a late reaction but if you're really interested in maths it doesn't matter :) I don't see any errors in this proof. Indeed, he selects a certain epsilon on purpose to obtain epsilon/2 in the end to make the proof more elegant. Greetings, Foxbox

Hi guys, I took a introductory thermodynamics course (to prepare for university) when I wondered what happened when one performs a free expansion... (like I mentioned in the first post of this thread: with a piston and two chambers, one vacuum, one filled with gas) Would it be reasonable...

Hello, Thank you for your information. Much appreciated ;) -FoxBox

Yes, in fact, forces have to exert in pairs. Here, the piston CANNOT exert a force if it's frictionless... Even if it would have a mass, it wouldn't be able to exert a force, would it? Thanks in advance...

But what is making the piston move then? Only a force can do that? It's the particular situation with the piston that i don't understand...

(the piston is indeed massless) A is the area of the piston. So, the gas puts a force F of p*A to the piston. It moves the piston all the way(x) to the right wall. So it does work: W=p*A*s=p*delta(V) But Zumdahl says no work is done. (Page 418...

Hello, I have a small problem concerning the free expansion of a gas. https://www.physicsforums.com/attachment.php?attachmentid=20388&stc=1&d=1252066499 The two chambers are separated by a movable piston (without friction). Obviously the gas will expand because it puts pressure p on the...