Thread: question about magnetic force

the formula for magnetic force is F = q(charge) x v(velocity) x B(magnetic field). the magnetic field only affects the perpendicular vector of the velocity, and exerts a centripetal force (inwards circular) on the charge. if this is true, then how does the hall's effect and velocity selectors work? (these imply that magnetic field exerts a non centripetal force with a direction on the charge)

also, could someone explain helical motion to me? im not sure which way the charge would spin, i know it occurs when the charge is traveling at a velocity neither parallel nor perpendicular with the magnetic field vector