I've got this home work question :- A straight conductor is stretched in the air and carries a current of 50A. the return conductor is some considerable distance away. calculate the magnetizing force at a radius of 8 cm.
So here is how I thought about it :-
formulae =
H = NI/l
N = 1 turn---------am I correct to assume this number of turns?
I = 50 A
L = C=2πr = 2π(0.008)= 0.5002m -------- am I correct to assume this length?

 

http://www.formuladirectory.com/user/formula/107

 

That formula is for wires in a circular configuration.

Amperes law is all you need.

Current divided by 2 pi time radius. All times the permeability coefficient. Which is 1 for free space.

 

Hello,

If you know how to calculate the force from the B field you can use Biot Savart to calculate the B field at a point anywhere outside the wire no matter what the length of the wire is or how it is shaped. Usually you have to calculate the force on a given object though.