Sending an electrical signal to a coil

It is amazing if one thinks about it, what it does. A coil of insulated wire.


We can take an electrical signal from a coil. For example from the coil of a microphone.


But we can do the reverse too.


Sending a music electrical signal to the coil of a magnetic recorder head and we record magnetism on magnetic tape music.


Or sending a music signal to a cutter head coil and engrave vibrations to disc and we therefore can make a record. An LP or 7in single or maxi single.


Or to a coil at the last stage of a transmitter and then feed an antenna and send music on air!
Radio.


All this due to the work of so many brilliant scientists and engineers such as Ampère, Oersted, Faraday, Tesla, Maxwell, Hertz,...