Formula Circular Motion in a Magnetic Field Cyclotron radius Velocity Charge Mass Magnetic field
$$r ~=~ \frac{ \class{brown}{m} \, \class{blue}{v} }{ |q| \, \class{violet}{B} }$$ $$r ~=~ \frac{ \class{brown}{m} \, \class{blue}{v} }{ |q| \, \class{violet}{B} }$$
Cyclotron radius
$$ r $$ Unit $$ \mathrm{m} $$ Cyclotron radius (also called Larmor radius) is the radius of the circular path along which a moving charge moves due to the Lorentz force.
Velocity
$$ \class{blue}{v} $$ Unit $$ \frac{\mathrm m}{\mathrm s} $$ Velocity component of the orbiting charge perpendicular to the magnetic field.
Charge
$$ |q| $$ Unit $$ \mathrm{C} $$ Amount of electric charge of the orbiting particle.
Mass
$$ \class{brown}{m} $$ Unit $$ \mathrm{kg} $$ Mass of the orbiting charged particle.
Magnetic field
$$ \class{violet}{B} $$ Unit $$ \mathrm{T} = \frac{\mathrm{kg}}{\mathrm{A} \, \mathrm{s}^2} $$ Magnetic field through which the charge moves.