Charged particles, such as electrons or ions, experience a force when they move through a magnetic field. This behavior is described by the Lorentz force equation:
F = q(v × B)
Where:
F is the magnetic force on the particle.
q is the charge of the particle.
v is the velocity vector of the particle.
B is the magnetic field vector.
The Lorentz force acts perpendicular to both the velocity of the charged particle and the direction of the magnetic field. This force causes the charged particle to move in a circular or helical path around the magnetic field lines, rather than accelerating it directly along the magnetic field lines. The velocity of the particle remains unchanged in the direction of the magnetic field.
The radius of the circular path that the charged particle follows is given by:
r = (mv) / (qB)
Where:
r is the radius of the path.
m is the mass of the particle.
v is the velocity of the particle.
q is the charge of the particle.
B is the magnetic field strength.
Key points to note about charged particle behavior in a magnetic field:
Direction of Motion: The charged particle will move in a curved trajectory perpendicular to both its velocity and the magnetic field direction.
Centripetal Force: The magnetic force acts as the centripetal force that keeps the particle in its circular path. As long as the magnetic force balances the centrifugal force, the particle will continue to move in a circular path.
Speed and Radius: The particle's speed and radius of curvature depend on its charge, mass, velocity, and the strength of the magnetic field. A stronger magnetic field will result in a tighter radius of curvature.
Helical Motion: If the charged particle is not moving strictly perpendicular to the magnetic field lines, it will follow a helical path, combining circular motion in the plane perpendicular to the magnetic field with a straight-line motion along the field lines.
No Work Done: The magnetic force does not do any work on the charged particle because the force is always perpendicular to the particle's velocity. This means that the kinetic energy of the particle is conserved.
Charged particle behavior in a magnetic field is a fundamental principle in electromagnetism and has applications in various fields, including particle accelerators, magnetic confinement in fusion reactors, and the operation of electric motors and generators.