Review -- how electric and magnetic fields are created Any charged particle creates an electric field at all points in space around it. A moving charged particle creates a magnetic field at certain points in space around it. (B=0 at points along the axis of the velocity of the particle.)
The force of a magnetic field on a charged particle The magnetic force is perpendicular to BOTH the velocity vector and the magnetic field vector and is given by the right hand rule (for a proton).
Right-hand Rule for Magnetic Force Point your fingers of your right hand in the direction of the velocity so that when you rotate your hand toward the magnetic field; then your thumb points in the direction of the magnetic force on a proton. (The force on an electron is in the opposite direction, or use your left hand.)
Uniform circular motionof a charged particle in a magnetic field Net force on an object in uniform circular motion has a magnitude
Crossed electric and magnetic fields