# Field problem

1. Oct 30, 2008

### tronter

If a particle moves in the +x direction with velocity $$v$$ in a box that has either a magnetic field or an electric field, and later it is moving in the +y direction with velocity $$v + 5$$, what field is in the box?

So it would be an electric field because magnetic fields can't change speed?

2. Oct 30, 2008

Re: Field

anyone?