1. The problem statement, all variables and given/known data Two charged particles (P & Q) are fired into a uniform magnetic field that is directed into the page. When a particle possessing charge q moved through a magnetic field B at a velocity v it experienced the lorentz force that has a magnitude of F=qvB. What is the sign of P and Q. The picture on the question looks similar to this just without the charges and P being the red line and Q being the blue,and the answer is the same as the picture. 2. Relevant equations F=qvB 3. The attempt at a solution I'm pretty sure you don't need to use the equation and I know the answer but I don't know how you come to the answer. I know you use the right hand rule and that the force on a negative and positive charge are in separate directions but I don't understand how you determine the charge of the particles.When I use the right hand palm rule, I have my palm facing up, my thumb to the right and the force pointing upwards. Is that right ? I don't think i'm applying the rules right because I think i've contradicted myself. When I use the right hand grip rule for the red line, I have my thumb pointing to the left. Does that mean I is towards the left so the current is following to the left ? I don't think ti's right ? But I don't understand how knowing the direction of current will help me determine the charge of the particle. Thanks!