Magnetic fields are created by particles in , never by particles at .
The of a particle in a magnetic field does not increase because its speed remains constant.
A straight current creates a magnetic which is directly proportional to its and to the distance to the point under consideration.
We call a current induced by the variation of the an induced current. This variation can be due to changes in the magnetic i, changes in the surface of the or changes in the formed by the magnetic induction vector and the surface vector.