Force on a current-carrying conductor — Determine

How do you determine the direction of the force on a beam of charged particles moving through a magnetic field?

Use Fleming's left-hand rule, treating the direction of motion of a positive charge as the 'current' direction (for a beam of electrons, use the direction opposite to their motion, since conventional current is opposite to electron flow): First finger = direction of the Field, seCond finger = direction of (conventional) Current/motion of positive charge, thuMb = direction of the force on the particles.