# It is a physical problem ~

1. Nov 28, 2005

### fufufuha

It is a physical problem.. plz help~

In certain experiments it is desirable to have a region of constant magnetic
flux density. This can be created in an off-center cylindrical cavity that is
cut in a very long cylindrical conductor carrying a uniform current density.
The uniform axial current density is J=az j
Find the magnitude and direction of B in the cylindrical cavity whose axis
is dispalced that of the conducting part by a distance d

I am depressed because of this problem. I have know idea...... ㅜㅜ

so... I submit this forum. plz help~

2. Nov 28, 2005

### Staff: Mentor

Welcome to the Physics Forums, fufufuha. This sounds like a homework problem, and if it is, it should be posted in the PF Homework forums:

https://www.physicsforums.com/forumdisplay.php?f=158

What textbook is this problem in? It sounds like they want you to calculate the B field inside a hollow cylindrical conductor, where there is a uniform DC current flowing up the cylinder wall. It sounds like the answer should show that the B field is fairly uniform off-axis from the center axis of the cylinder. My guess is that you can use Ampere's Law for this, but my E&M books are all at work at the moment, and I'm home...

Edit -- after re-reading your post, I don't think that I understand the geometry of the conductor and the hollow cylinder portion after all. Is there a diagram associated with this problem?

Last edited: Nov 28, 2005
3. Nov 29, 2005

### fufufuha

I'm sorry that I'm not good at this forum.

Anyway~ Thanks berkeman