To determine the direction Lorentz force , was founded rule of thumb of the left hand.It is easy to remember because direction is determined with the help of the fingers.Open palm of his left hand and straighten all the fingers.Thumb bend at an angle of 90 degrees with respect to all other fingers on the same plane with the palm.
Imagine that four fingers of his hands, you hold together, indicate the direction velocity of the charge, if it is positive, or the opposite direction of speed , if the charge is negative.
magnetic induction, which is always directed perpendicular to the velocity, will thus enter into his palm.Now look, is pointing his thumb - this is the direction Lorentz force .
Strength Lorentz may be zero and not have a vector component.It occurs when the trajectory of a charged particle is parallel to the magnetic field lines.In this case, the particle has a rectilinear path of movement and a constant speed.Lorentz Force does not affect the movement of particles, because in this case it is absent.
In the simplest case, the charged particle has a motion path perpendicular to the magnetic field lines.Then the Lorentz force creates a centripetal acceleration, causing a charged particle moving in a circle.