Magnetic field by that loop. Ampère's law is always valid for steady currents and can be used to calculate the -field for certain highly symmetric situations such as an infinite wire or an infinite solenoid. In a modified form that accounts for time varying electric fields, Ampère's law is one of four Maxwell's equations that describe electricity and magnetism. A charged particle moving in a -field experiences a "sideways" force that is proportional to the strength of the magnetic field, the component of the velocity that is perpendicular to the magnetic field and the charge of the particle. This force is known
Induction coil current must be repeatedly connected and disconnected to create the magnetic field changes needed for induction. To do that, induction coils use a magnetically activated vibrating arm called an "interrupter" or "break" ("A") to rapidly connect and break the current flowing into the primary coil. The interrupter is mounted on the end of the coil next to the iron core. When the power is turned on, the increasing current in the primary coil produces an increasing magnetic field, the magnetic field attracts the interrupter's iron armature ("A"). After a time, the magnetic attraction overcomes the armature's spring force, and the