Low frequencies travel farther mostly because they propagate along the surface of the earth. High frequency FM signals are basically line of sight. Under the right conditions, AM signals will bounce off of the ionosphere and can travel around the globe. This is not possible with high frequency signals.
In this way, how do FM radio waves travel?
Artwork: How radio waves travel from a transmitter to a receiver. 1) Electrons rush up and down the transmitter, shooting out radio waves. 2) The radio waves travel through the air at the speed of light. 3) When the radio waves hit a receiver, they make electrons vibrate inside it, recreating the original signal.
Why is there AM and FM radio?
FM radio works the same way that AM radio works. The difference is in how the carrier wave is modulated, or altered. With an FM broadcast, slight changes in amplitude don't matter -- since the audio signal is conveyed through changes in frequency, the FM receiver can just ignore changes in amplitude.