EM Research (RF):
FM modulation :
High Frequency at + amplitude of sign wave
low Frequency at - amplitude of sine wave
Increased Amplitude increase current
Increased Voltage is Increase difference in potential.
FM carrier is rotated 90 degrees fro axis placing the Amplitude within the magnetic/Inductance field
Therefore the carrier of the FM modulation actually the induction amplitude (of the magnetic field.
Basically FM modulation is spinning the axis of the amplitude in the Imaginary axis and as it does so the Amplitude in that spin causes the amplitude to change in 'relativity perspective' and reduce the frequency of the perceived signals -
Basically FM is just AM spun in the magnetic or you can say imaginary field and create a relativistic perception of the change of Amplitude.
Think of FM modulation as the Inductance modulation and the Amplidude is in the magnetic field - Same as AM just rotated 90 degrees
As you twist the angle from 0 to 90 the amplidude of the wave decreases and the Frequency in FM flattens. As you rotate if toward you the Amplitude increases and the perceived frequency increases.