The radio was discovered in 1894 but was more known by public in 1896.
The radio was invented by Gugliegmo Marconi an italian inventor. But later was proven that Nikola Tesla invented the fundamentals for the radio transmission before Marconi even thought of it.
The radio works like this "the sound waves of a program go into a microphone that has electrical current running through it. These sound waves create vibrations in the current as they travel through wires to a control room"
In more detail:
frequency is produced, microphone converts the sound wave into a electrical signal, the electrical wave traveling through the microphone is the original sound wave, the signal is transmitted by a radio broadcast tower, then the signal is received by another radios antenna
The difference between am and fm radio am is amplitude modulation and fm is frequency modulation. Modulation is modifying the frequency depending on the information sent.
AM ranges from 535 to 1705kbz
FM goes from 88 to 108MBz
