Question

Problem 27

Answer 1

Given information

Given:

Explain why AM radio signals can usually be heard behind a hill, but FM often cannot.

Radio signals, as we shall see, are carried by electromagnetic waves whose wavelength for AM is typically  to  m and for FM about  m.

Step-by-step explanation

Step 1.

The wavelength of the transmissions is the reason behind this.

 

Because AM modulation consists of adjusting the amplitude of the carrier wave according to the modulating signal, which is precisely the information that will be conveyed, AM signals may travel vast distances due to their larger wavelength.

 

Because these waves are big, they bounce off the ionosphere and may travel enormous distances, we can hear signals from the opposite side of the Earth if we have a decent AM signals receiver (on the order of hundreds of meters).

 

Even though AM signals may travel great distances, they are not the most often used. The AM transmissions, on the other hand, need a lot of power from the transmitters, and the audio quality is poor, with no stereo.

 

The wavelength of FM broadcasts is short (about three meters long). Their transmitters are compact, need little power, and offer excellent audio quality due to frequency modulation.