# Homework Help: Cylindrically symmetric current distribution: Magnetic field in all space

1. Mar 23, 2007

### JamesTheBond

1. The problem statement, all variables and given/known data

a. An infinite cyclindrically symmetric current distribution has the form
$$\vec J (r, \phi, z) = J_0 r^2/R^2 \ \ \ \vec\hat \phi$$ for $$R<r<2R$$. Outside the interval, the current is 0. What is the field everywhere in space?

b. An infinite cyclindrically symmetric current distribution has the form
$$\vec J (r, \phi, z) = J_0 r^2/R^2 \ \ \ \vec \hat z$$ for $$R<r<2R$$. Outside the interval, the current is 0. What is the field everywhere in space?

2. Relevant equations

Ampere's Law
Biot Savart?

3. The attempt at a solution

r<R B = 0

r>2R B= 0

???

I don't know where to start.

Last edited: Mar 23, 2007
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