How to define the direction of Lorentz force

How to define the direction of Lorentz force

Lorentz force defines intensity of impact of electric field on a dot charge. In some cases it is meant as force with which the charge of q which moves with a speed of V is affected by magnetic field, in others total influence electric means and magnetic water.


1. To define the direction of Lorentz force, the mnemonic rule of the left hand was created. It is easy to remember it thanks to the fact that the direction decides on the help of fingers. Open a palm of the left hand and straighten all fingers. Unbend a thumb at an angle in 90 degrees in relation to all other fingers, in one plane with a palm.

2. Present that four fingers of a palm which you hold together specify the direction of speed of the movement of a charge if it positive, or the direction opposite to speed if a charge negative.

3. The vector of magnetic induction which is always directed perpendicular to speed, thus, will enter a palm. Now look where specifies a thumb - it is and there is a direction of Lorentz force.

4. Lorentz force can be equal to zero and not have a vector component. It occurs when the trajectory of charged particle is located parallel to power lines of magnetic field. In that case the particle has a rectilinear trajectory of the movement and constant speed. Lorentz force does not influence in any way the movement of a particle because in this case it in general is absent.

5. In the simplest case charged particle has the trajectory of the movement perpendicular to power lines of magnetic field. Then Lorentz force creates centripetal acceleration, forcing charged particle to move on a circle.

Author: «MirrorInfo» Dream Team