Practical Electron Microscopy and Database

Assuming a charged particle or an electron moving in a plane perpendicular to a magnetic field, they will move in a circular orbit with the magnetic force playing the role of centripetal force. The direction of the centripetal force obeys the right-hand rule.

The centripetal and the magnetic forces can be given by,

      F = mv²/R = q v B ------------------------------ [4295a]

The radius of the circular path R can be given by,

      R = m v/q B ------------------------------ [4295b]

where,

      m -- Mass of the charged particle or electron
      v -- Speed of the charged particle or electron
      q -- Charge of the charged particle or electron
      B -- Magnetic flux density

Figure 4295. Schematic illustration of orbit of a charged particle (a) and an electron (b) in a magnetic field. R is the radius of the path of the charged particle and the electron in a magnetic field.