physics EM
posted by Spencer on .
You have a 0.600mlong copper wire. You want to make an Nturn current loop that generates a 1.30 mT magnetic field at the center when the current is 0.600 A. You must use the entire wire.
What will be the diameter of your coil?
this doesnt seem that hard but I cant figure what I need to use.

The value of coil diameter D will depend upon the value of N. There will be only value of D possible with the length L that you have
B (at the center of the coil) = N*mu*I/D
"mu" = 4 pi*10^7 Weber*Amp/meter
N = L/(pi*D) determines how many turns you can have with the available wire length L
B = [L/(pi*D)]*mu*I/D
= L*mu*I/(pi*D^2)
Solve for D 
thanks i guess i need to read up on the turns in coils.