# Magnetic Force of a current carrying wire loop on a magnetic object

let's say we have a current carrying wire loop WITHOUT AN EXTERNAL MAGNETIC FIELD. It produces a magnetic field on its own. what would the magnetic field and force of this loop on a charge or a magnetic object(or whatever) outside the loop?

I always find the equation of F = IBL which is the force on the on loop from an external magnetic field but i can never find the force that the loop itself produces.

Like i am trying to calculate the force from the loop on an iron ball or find the magnetic field produced by just the loop but outside the loop. If i can get the magnetic field outside the loop then i can derive the force that i need using F = Del(m X B).

## 2 Answers

Magnetic force is experienced by moving electric charges. You need find out the magnetic field produced by that ring or that current carrying object at a point in space and then use the formula $\vec F=q\vec v\times \vec B$.

well its the same case as in electrostatics. a point charge kept isolated can never feel the force due to its own electric field. like same way ANY source of a field can never be influenced by its own field. also recall that a value of magnetostat ic field diverges at its own location.(appears singularity)

• I am asking about the force the magnetic object will feel from the loop. Not the force the loop feels from the field it is producing. Feb 6, 2017 at 4:41
• oh iam sorry. i misunderstood u, ok force on other current element like moving charge is given by Lorentz force F=q(v×B). for another current loop F= k (i.dl×B) is it helpful now?? Feb 6, 2017 at 4:49
• What if the other object doesn't have a magnetic field and there is no other source of the magnetic field other than the loop? Like i am trying to calculate the force from the loop on an iron ball or find the magnetic field produced by just the loop but outside the loop. I know the equations that you posted and i also found equations for the magnetic field inside the loop but i can't find an the force on a regular old iron ball/object or the magnetic field outside the loop. If i can find the magnetic field, i can derive the equation for force. Feb 6, 2017 at 5:26
• well if other object doesnot have any magnetic properties then no force felt. however the B of loop will try to magnetise , or induce magnetic properties in the sphere along B of loop. Feb 6, 2017 at 5:46