Electric charge moving in an electric (electrostatic) field (velocity being perpendicular to its field lines)
Electric charge moving in a magnetic field (velocity being perpendicular to its field lines)
Lorentz force F acts as centripital force and the charge will do a circular motion:
F=Fc <=> qvB=mv2/R <=> R=mv/qB
The radius of the circular motion, termed gyroradius, Larmor radius, or cyclotron radius is given by the above equation.
Applications : Cyclotron, Mass Spectrometer
Electric charge moving in an electric and a magnetic field experiences the Lorentz force