# Force on a Wire In Uniform Magnetic Field

1. Oct 11, 2012

### bmb2009

1. The problem statement, all variables and given/known data
A long wire lying along the x-axis carries a current of 2.60 A in the +x direction. There is a uniform magnetic field present, given by B=0.003i + 0.004j + 0.002k, where i, j, k are the unit vectors along the cartesian coordinate axes') in units of Tesla. Calculate the y-component of the magnetic force acting on a segment of wire of length L = 17.5 cm.

2. Relevant equations

3. The attempt at a solution

I tried using the formula F=ILBsin@
where F=force, I=Current, B=magnetic field in tesla, sin@=1 (b/c y axis is perpendicular to x so @=90 degrees).
but that didn't work...I don't really know how to make sense of the B field equation?

Help?

2. Oct 12, 2012

### tiny-tim

hi bmb2009!

(have a theta: θ … or pick it up from the Quick Symbols box to the right of the Reply box )
no, the θ in ILBsinθ is the angle between I and B

(the force F = LI x B is perpendicular to both I and B)

that gives you the magnitude of F, then find the component in the y direction

3. Oct 12, 2012

### bmb2009

Can you be more thorough? Like i have no idea where to start our teacher never went over anything close to something with a b field given as components... so I Don't know how to find an angle from it and even if I did I would know how to find the Y component afterwards..

4. Oct 12, 2012

### bmb2009

I tried:

since the B field and current are parallel in the x direction the f=0
so the magnitude of the force is the force from the y and z components which i plugged in to get a number but how would you calculate of Y component without any more information?

5. Oct 12, 2012

### tiny-tim

show us your cross product calculations for the total F