The magnetic field B is defined from the Lorentz Force Law, and specifically from the magnetic force on a moving charge: The implications of this expression include: 1. * The force is perpendicular to both the velocity v of the charge q and the magnetic field B. 2. * The magnitude of the force is , where θ is the angle < 180 degrees between the velocity and the magnetic field. This implies that the magnetic force on a stationary charge or a charge moving parallel to the magnetic field is zero. 3. * The direction of the force is given by the right hand rule. The force relationship above is in the form of a vector product.