Force on Current conducting wire

[rayray17]

This maybe a stupid question but i have always ignored the field created by the wire as i believed that it does not affect the wire itself but only the current and length matter when a wire is in an external field and force needs to be found.

Looking at solutions to a trial exam apparently the field generated by the wire is important as well in the force created.
Could someone please explain to me what is actually happening when a current conducting wire is entered into a magnetic field and also a diagram of the two fields interacting if you know of one online.

Thanks

[sh00my]

I think I understand your problem.
If it is what im thinking I too had this problem.

Basically, the magnetic feild generated from a conducting wire will add vectorially with the external magnetic feild, which in turn, will produce a net magnetic feild down amd hence produce a force in that direction. Pretty sure this is beyond the scope of the course, it is adequate to mention that the force produced is a result from the "right hand slap rule".

[Phantom-II]

lol, is this from the insight exam?

im fairly certain the induced magnetic field does not effect the current carrier itself and that explanation is incorrect. Current carriers will have a circular field around it, and ONLY around it, not through it, so the vector through the conductor is only from the applied magnetic field.

As for the induced force, i think it is from cross multiplication of the I and B vectors ( as opposed to dot product in specialist math). But yeah, just say right hand slap rule!

[rayray17]

yeah, this question is in both insight 2009 and 2011.

I know it doesnt make sense as with the wire opposite ends have different directions of field, so a proper net field cant be created.

Insights answer is along the lines of 'The self-magnetic field of the current-carrying conductor interacts with the external magnetic
field. Vector addition of the two fields results in a net field and the conductor experiences a force to realign it in the direction of the net field.

However i dont think for the question 'Explain, referring to magnetic fields, the principle reason why the current-carrying conductor
experiences the magnetic force when placed in the magnetic field' which is two marks saying right hand slap rule is correct either.

any ideas of a proper answer?

[sh00my]

Insight is correct, It's beyond the scope of the course. The reason for the force is due to magnetic feilds adding vectorially (in other words right hand slap rule).