Charged Particles Moving in a Magnetic Field
In this demonstration particles are entering the region of the magnetic field with their velocoties being perpendicular to the magnetic field lines. In such a situation the magnetic force serves to move the particles in a circular path. According to the "right hand rule" the magnetic force acting on the particle always remains perpendicular to its velocity.
The magnitude of the magnetic force is F = q V B , where q is the magnitude of the charge of the particle, V its velocity, and B is the magnetic field.
This force can be also considered as the centripetal force Fc = m V2 / R , where m is the particle's mass and R is the radius of the circular tragectory.
Making two above expressions equal to each other and solving the resulting equation for R we can easily find that the radius R of the circular path is proportional to the velocity of the particle. R = m V / q B .
© Copyright 1997, Sergey Kiselev and Tanya Yanovsky-Kiselev