Simplify the following text for a Grade 9 native English-speaking person.
Original: In physics , cyclotron frequency is the frequency of a charged particle moving perpendicularly to the direction of a uniform magnetic field , i.e. a magnetic field of constant magnitude and direction . Since that motion is always circular , the cyclotron frequency is well defined .
Simplified: A moving charge in a cyclotron will move in a circular path under the influence of a constant magnetic field .