Magnet , around for ferrite and SmCo, about for NIB and lower for flexible ceramics, but the exact numbers depend on the grade of material. An electromagnet, in its simplest form, is a wire that has been coiled into one or more loops, known as a solenoid. When electric current flows through the wire, a magnetic field is generated. It is concentrated near (and especially inside) the coil, and its field lines are very similar to those of a magnet. The orientation of this effective magnet is determined by the right hand rule. The magnetic moment and the magnetic field of
Induction coil radio transmitters, arc lighting and quack medical electrotherapy devices from the 1880s to the 1920s. Today its only common use is as the ignition coils in internal combustion engines and in physics education to demonstrate induction. An induction coil consists of two coils of insulated wire wound around a common iron core "(M)". One coil, called the "primary winding" "(P)", is made from relatively few (tens or hundreds) turns of coarse wire. The other coil, the "secondary winding," "(S)" typically consists of many (thousands) turns of fine wire. An electric current is passed through the primary, creating a magnetic field.