# Electricity and Magnetism

1. Apr 25, 2014

### Rsealey

1. The problem statement, all variables and given/known data
A charged particle moves in a straight line through a particular region of space. Could there be a nonzero magnetic field in this region? In either case, include a sketch as well as prose in your justification.

2. Relevant equations

3. The attempt at a solution
The force that a magnetic field exerts on a charged particle moving through it is given by F=qvB, sin theta = qvB where B is the component of the field perpendicular to the particle’s velocity. Since the particle moves in a straight line the magnetic force must be zero.

2. Apr 25, 2014

### Staff: Mentor

OK.

The magnetic force is zero. What about the field?

3. Apr 25, 2014

### BiGyElLoWhAt

Hmmm...
Another way to look at that relationship is $\vec{F}=q\vec{v}\times \vec{B}$
It's essentially the same relationship, but I think you're looking at it wrong by only looking at the perpendicular part of the magnetic field.