# Magnetic force question - should be easy

1. Nov 16, 2008

### bcjochim07

1. The problem statement, all variables and given/known data

1) An electron moves in a magnetic field B = .50 i with a speed of 1.0 x 10^7 m/s 45 degrees above the positive y axis. What is the magnetic force on the electron?

2. Relevant equations

3. The attempt at a solution
1)This should be an easy question, but I am getting my signs messed up.

F=qvBsin(theta) q = 1.60*10^-6 v= 1.0 * 10^7 m/s B = .50 T
F= (1.60*10^-6)(1.0*10^7)(.50) = 8.0 *10 ^ -13 +

Now, using the right hand rule I believe that if this were a proton, the components would be
(-5.66*10-13)i + (5.66*10-13)k and so then I just flipped the signs:

(5.66*10-13)i - (5.66*10-13)k , but my book says they are both negative.

2. Nov 16, 2008

### bcjochim07

any thoughts would be greatly appreciated

3. Nov 17, 2008

### bcjochim07

I have also tried doing the cross product between v and B and then multiplying by 1.60 * 10 -19 but then I come up with a positive z component and a negative j component