Draft:Magnetic force

In electromagnetism, Magnetic force arises from moving electric charges and is one aspect of the unified electromagnetic interaction. In classical physics, a magnetic field B is defined by the force it exerts on a moving charge. Specifically, a charge q moving with velocity v in a magnetic field experiences a Lorentz force $F=q.v\times B$, always perpendicular to v and B. Richard Feynman emphasized that “one part of the force between moving charges we call the magnetic force." It is really one aspect of an electrical effect. In other words, magnetism naturally emerges when charges move, and via special relativity the electric and magnetic fields are interrelated. Faraday introduced the modern field concept (1831), showing that changing currents produce magnetic fields that in turn induce electric effects.

Definition

Magnetic field definition: A magnetic field B at a point in space is operationally defined by the force on a test charge: $F=q.v\times B$. The direction of B is given by the right-hand rule (from North to South outside a magnet). The magnitude of the force is $F=q.v\times B$, where θ is the angle between v and B. The SI unit of B is the tesla (T).