[[Electrodynamics MOC]]
# Lorentz force law
**Lorentz's force law** describes how the [[electric field]] and [[magnetic field]] affect a moving charge
$$
\begin{align*}
\vab F = q(\vab v \times \vab B + \vab E)
\end{align*}
$$
where $\vab B: \pu{ N.s.C-1.m-1 = T }$ is the **magnetic field strength**.
Along with [[Maxwell's equations]], it is one of the fundamental rules describing [[Electrodynamics MOC|Electrodynamics]].
It is also the principle that enables the [[Velocity selector for charged particles]].

## Remarks 

- Notice that by nature of the forces perpendicularity,
  any moving charged particle experiences **centripetal acceleration** in a magnetic field
  and thus if the particle is otherwise free it undergoes circular motion.
  If there is a component of the particle's velocity that is parallel to the magnetic field,
  the overall effect is a helical path.
  The magnetic force **does no work**, 
  rather it changes the direction of a charged particle's existing kinetic energy.

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#state/tidy  | #SemBr | #lang/en