Determining the Optimal Thickness for a 30mH-Solenoid Inductor

[chemic_23]

Homework Statement

hi, i just have few questions on how to make a 30mH-inductor (solenoid). I have an enameled copper wire which i will wrapped into a 7-inch rebar having 12mm diameter. In order to determine the number of turns, i made some calculations:

Homework Equations

L=(uAN^2)/d

The Attempt at a Solution

My computations are as follows:
L=30e^-3 H
u=100*4*pi*10^-7 (permeability of the rebar=100 (just an assumption))
A=pi*(6e^-3) m^2 (r=12mm/2=6mm=6e^-3 m)
d=0.1778 m

N=613 turns

my question is:
-how will i know what is the thickness of the copper wire I'm going to use?
-and, is my permeability assumption correct? (i don't really know what is the exact permeability of the rebar)

some photos of rebar:
http://www.circlecityrebar.com/istock_rebar6.jpg"
http://rebar.materialsuppliers.com/Rebar-big.jpg"

please help thanks!

 

[supratim1]

thickness of wire doesn't matter, except the fact that it determines the resistance of the solenoid. check the permeability of the material the rebar is made of, on net, just search in google.

 

[chemic_23]

so, in order to have 30mH, i need to make 613 turns?

 

[supratim1]

if permeability is actually 100, and ur calculations are correct (i have not checked them), then your answer is 613 turns.

 

[chemic_23]

i've found out that its permeability is 2000.. thanks :)