Describe the features of the magnetic force acting on a charged particle moving inside a magnetic field.

(N/A) The magnetic force $\overrightarrow{F_{m}}$ acting on a charge $q$ moving with velocity $\vec{v}$ in a magnetic field $\overrightarrow{B}$ is given by:
$\overrightarrow{F_{m}} = q(\vec{v} \times \overrightarrow{B})$
$\therefore F_{m} = q v B \sin \theta$,where $\theta$ is the angle between $\vec{v}$ and $\overrightarrow{B}$.
Features:
$(i)$ The force depends on the charge $q$,velocity $\vec{v}$,and magnetic field $\overrightarrow{B}$. The force on a negative charge is opposite to that on a positive charge.
$(ii)$ The force is a vector product of velocity and magnetic field. If $\theta = 0^{\circ}$ or $\theta = 180^{\circ}$,then $F_{m} = q v B \sin(0^{\circ}) = 0$ or $F_{m} = q v B \sin(180^{\circ}) = 0$. The force acts in a direction perpendicular to both the velocity and the magnetic field,determined by the right-hand rule.
$(iii)$ The magnetic force is zero if the charge is stationary $(v = 0)$. Thus,only a moving charge experiences a magnetic force.