Direction of magnetic field problem (Right Hand Rule)

[Tomi Kolawole]

Homework Statement

Homework Equations

The Attempt at a Solution

I have already solved for the magnetic fields everywhere AND THE magnetic field at R>F = (U/2*PI*R)*(I2-I1)

My only problem is i know i use the right hand rule to determine the direction of the magnetic field B as clockwise or counter clockwise, however there are 2 currents i2 and i1 so which current do i put my thumb to determine the direction of B at R>F?

 

[kuruman]

I have already solved for the magnetic fields everywhere AND THE magnetic field at R>F = (U/2*PI*R)*(I2-I1)

This is incorrect. Your expression in the region R > F is missing a denominator. Anyway, since your expression has (i₂-i₁), put your thumb in the direction of i₁ and do the right hand rule thing. Ultimately, the direction the B-field will depend on which of the two currents is greater than the other. If your are given that i₂ > i₁, then the direction will be as you have chosen, else it will be the opposite direction.

 

[Tomi Kolawole]

They didnt say which is greater than the other in the question stated above, so how can i know?

 

[kuruman]

You can't possibly know unless you have numbers or at least someone tells you which current is greater than the other.