Answer:
K remains constant
Explanation:
The magnetic force does not do any work on the ion.
In fact, the magnetic force due to a magnetic field is always perpendicular to the motion of the charge itself. Keep in mind that the work done by a force is given by
[tex]W=Fdcos \theta[/tex]
where F is the magnitude of the force, d is the displacement of the particle, and [tex]\theta[/tex] is the angle between the direction of the force and the displacement. Since the magnetic force is perpendicular to the displacement of the ion, then [tex]\theta=90^{\circ}[/tex] and [tex]W=0[/tex], so the work done is zero.
For the work-energy theorem, the work done on the ion is equal to the variation of its kinetic energy:
[tex]\Delta K=W[/tex]
However, since W=0, then [tex]\Delta K=0[/tex], which means that the kinetic energy of the ion does not change.
