# Magnetic Force

1. Jun 27, 2007

### jesuslovesu

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

An electron has a velocity of 1.20 x 10^4 m/s in the +x direction. An acceleration of 2.00 x 10^12 m/s/s in the +z dir in a uniform electric and magnetic field. The electric field is 20.0 N/C in the +z direction. What can you determine about the magnetic field? What can you not determine?

2. Relevant equations

F = q(v x B)
e = -1.67 x 10^-19 C
3. The attempt at a solution

I can see why the mag. field would be Bz = 0 and By = something.
But I'm not sure how to find the value of By or why it will have a possible value to Bx.

I can find the electric force, but I don't know how I could relate that to magnetic force. F = Eq.

I also don't really know how to use the acceleration, it seems that the acceleration would only be useful if I needed to use the gravitational force... (I can't say the magnetic force is equal to mass*acceleration can I?)

2. Jun 27, 2007

### Staff: Mentor

The acceleration allows you to determine the net force on the electron.

3. Jun 27, 2007

### jesuslovesu

Is using Net force = Eq + qvxB on the right track?

4. Jun 27, 2007

### Staff: Mentor

Yes, something like that. (I presume you can ignore gravity.)