# Homework Help: I got the formula, what does the angle effect? Net Magnetic force

1. Nov 6, 2005

### mr_coffee

Hello everyone, I think im missing this problem because there is an angle invovled, but it doesn't seem to matter what angle it is from what my lecture notes say. but heres the question:
The bent wire shown in Fig. 28-39 lies in a uniform magnetic field. Each straight section is 2.1 long and makes an angle of = 62° with the x axis, and the wire carries a current of 2.0 A. What is the net magnetic force on the wire in unit-vector notation if the magnetic field is given by each of the following?
Here is the picture:
http://www.webassign.net/hrw/28-39.gif

Here is my work:
http://show.imagehosting.us/show/891660/0/nouser_891/T0_-1_891660.jpg
any ehelp would be great!

THe formula states: Fbtotal= F1 + F2 + F3 + ... + Fn then it says: F = I(L1 + L2 +....+Ln) x B

Last edited by a moderator: Apr 21, 2017
2. Nov 6, 2005

### whozum

Right, the angle comes in with the cross product at the end..

3. Nov 7, 2005

### mr_coffee

can you expland that explanation alittle more? How do you apply the cross product with the angle? I know the dot product has like AB = cos/|A||B| but i never heard of one for the cross product of A B.

4. Nov 7, 2005

### Staff: Mentor

The magnitude of $\vec A \times \vec B$ is $AB \sin {\theta}$.

5. Oct 28, 2008

### s7b

Wouldn't both the forces be equal and just opposite in direction therefor the net force is zero??

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