# Homework Help: Find the x-component of the magnetic force on the wire

1. Feb 21, 2010

### Charanjit

1. The problem statement, all variables and given/known data:
A wire with a length of 29.0 cm lies along the z-axis and carries a current of 9.00 A in the +z-direction. The magnetic field is uniform and has components Bx = -0.204T, By = -0.968T, and Bz = -0.328 T

2. Relevant equations
1. Find the x-component of the magnetic force on the wire. Ans: 2.5N
2. Find the y-component of the magnetic force on the wire Ans: -0.532N
3. Find the z-component of the magnetic force on the wire
4. What is the magnitude of the net magnetic force on the wire?

3. The attempt at a solution.
I solved question 1 and 2. But I don't fully understand why. For question 1 I used the force in the y direction and in 2 I used the force in the x direction. But why like that?
For #3, I used the z direction force, and its not correct. So kind of confused.

2. Feb 21, 2010

### Juan Pablo

The force on a wire in magnetic field B is given by

$$\vec{F_B} = I \vect L \times \vect B$$ where L is a vector that points in the direction of the current and magnitude the length of the wire.

So,

$$\vec{L} = 0.29k$$
$$\vec B = -2.04i-0.968j-0.328k$$

Compute the cross product using a determinant.

3. Feb 21, 2010

### Charanjit

Oh ok, kind of forgot myu calculus a bit. Read over my notes from Cal class, makes sense now. Thanks.