(i) A charged particle travels undeviated through a magnetic field \(\vec{B}\) if its velocity \(\vec{v}\) is parallel or antiparallel to . In this case, the magnetic force on the charge is zero.
(ii) A charged particle travels in a circular path within a magnetic field \(\vec{B}\) if its velocity \(\vec{v}\) is perpendicular to \(\vec{B}\).
(iii) A charged particle travels in a helical path through a magnetic field \(\vec{B}\) if its velocity \(\vec{v}\) is inclined at an angle θ to \(\vec{B}\) , 0 < θ < 90°. In this case, the component of \(\vec{v}\) parallel to \(\vec{B}\) is unaffected by the magnetic field. The radius and pitch of the helix are determined respectively by the perpendicular and parallel components of \(\vec{v}\)
