Calculate the B field inside and outside a wire

[DODGEVIPER13]

Homework Statement

A long, straight wire of radius a has current density J = J0e−β(α−ρ)uz where β is a
constant and ρ < α. Determine B inside and outside the wire.

Homework Equations

J=I/((pi)a^2)
B=(μIρ)/(2(pi)(a)^2)

The Attempt at a Solution

Here is what I did B=(μρ/2)J0e^(-β(alpha-ρ))

 

[DODGEVIPER13]

Is the problem confusing?

 

[darkxponent]

Is the problem confusing?

Not at all. First find i by integrating J then find B. di = JdA

 

[DODGEVIPER13]

So ∫J0e^-β(α-ρ) from 0 to a but what should I integrate with respect too?

 

[DODGEVIPER13]

J=di/dA maybe?

 

[DODGEVIPER13]

well since beta is constant and alpha is greater than rho then e^(-beta(alpha-rho)) whould go to 0 if I took the limit from 0 to infinty

 

[DODGEVIPER13]

hmmm well I guess the problem does not consider time as it uses J0 which I assume stands for the intial value

 

[DODGEVIPER13]

So my limit I idea is flawed then

 

[DODGEVIPER13]

Anything else?