Motion of a Charged Particle in a Magnetic Field

Electric and magnetic forces both affect the trajectory of charged particles, but in qualitatively different ways.

If a charged particle's velocity is parallel to the magnetic field, there is no net force and the particle moves in a straight line.

Since the magnetic force is always perpendicular to the velocity of a charged particle, the particle will undergo circular motion.

Helical motion results when the velocity vector is not perpendicular to the magnetic field vector.

Cyclotrons, magnetrons, and mass spectrometers represent practical technological applications of electromagnetic fields.