Yesterday I asked a question regarding the right hand rule and Lorentz law. I now understand how the right hand rule is applied but the examples I have looked at all involve a positive charge. My question is what effect does a negative charge have on the right hand rule? If for example a positive charge is moving in a positive x direction when it enters a magnetic field and then starts to describe a circle in an anticlockwise direction (in the xy plane), by using the right hand rule I would say that the magnetic field would be in the positive z direction... Would you agree? Now if a negative charge were to enter the same field and describes the same anticlockwise circle, how do I apply the right hand rule in this situation? Would I simple say, ok for a positive charge the direction of the magnetic field was in the z direction, so for a negative charge, the direction must be in the -z direction?