ABSTRACT
A charged particle (Section 6.1) placed in an electric field, experiences an acceleration (Section 6.2) that increases as the electric charge increases and the mass decreases. In the presence of a magnetic field (Sections 6.3 and 6.4), the charged particle rotates around it, with an angular velocity that increases with increasing charge and decreasing mass. The superposition of these two motions (Sections 6.6 and 6.7) specifies the trajectory of the charged particle in an external electromagnetic field, uniform or not. Electromagnetic fields may be used to “focus” a beam of charged particles (Section 6.8), distinguish between positive and negative charges, and separate particles or atoms with different charges and/or masses (Section 6.9). The motion of charged particles in electromagnetic fields can be observed in laboratory experiments and occurs in astrophysics, for example, in the ionosphere of the earth and interplanetary space; some electrical devices, like cathode ray tubes and television screens, are based on deflection of the trajectories of charged particles.
