Final answer:
AM signals are better at diffracting around obstacles like buildings and hills due to their longer wavelengths, which means they can be received without a direct line of sight.
Step-by-step explanation:
AM signals, which stand for amplitude modulation, are known for having longer wavelengths that allow them to diffract, or bend, around obstacles such as buildings and hills. This is similar to how ocean waves move around large rocks. This diffraction ability lends to their capability to be detected more readily without a direct line of sight. On the other hand, FM signals (frequency modulation) and TV signals require a line of sight between the broadcast antenna and the receiver for best reception.
This is why FM, TV, and mobile phone antennas are placed on tall structures; it's to maintain an unobstructed path. Furthermore, FM signals are less susceptible to noise because noise generally affects the amplitude of waves, and FM radio is more dependent on frequency variations than amplitude.
The inherent difference between AM and FM signals lies in the way information is carried; AM is modulated in amplitude while FM is modulated in frequency. Each type of modulation has its benefits, but in terms of overcoming physical barriers, AM signals have an advantage due to their longer wavelengths and superior diffraction capabilities.