# Lorentz force

1. Dec 10, 2011

### Gavroy

hi

i was wondering whether the lorentz force is just caused by the fact, that moving charges produce a magnetic field, just like every current does, and this magnetic field interacts with the magnetic field in the environment, that causes the force or whether the lorentz force has nothing to do with this and is a new effect in electromagnetism?

2. Dec 11, 2011

### Staff: Mentor

I don't think that the Lorentz force can be derived from Maxwell's equations, but must be added as an extra postulated equation. Generally, I think of the Lorentz force equation as the definition of the fields.

3. Dec 12, 2011

### vanhees71

The Lorentz force can be derived from rather weak principles about forces on relativistic particles. Among other possibilities, this leads to a Lagrangian, where the force is mediated by a (massless) vector field, and when you derive the equations of motion for the point particles and neglect the backreaction of the partilcles' radiation field on the particles, you arrive at the Lorentz force.

4. Dec 12, 2011

### Bill_K

The Lorentz force, of course, is just the Coulomb force viewed in a moving frame.