Question

use the text to compare and contrast. am and fm are methods of broadcasting radio signals with electromagnetic waves. am stands for amplitude modulation. developed in the 1870s, it works by varying the amplitude of a radio signal, while the frequency remains the same. fm stands for frequency modulation. instead of varying the amplitude, fm varies the frequency of the signal, while the amplitude stays the same. fm was first used in the 1930s. each method has distinct advantages. am radio can be transmitted over long distances, yet fm cant; fm signals are easily disrupted by obstacles such as tall buildings and mountains. am signals can be detected by simple equipment, but fm requires complex transmitters and receivers. one advantage of fm over am is sound quality, because fm is less susceptible to interference and noise. for this reason, most music stations prefer fm, while news stations still use am. was developed in the 1870s amplitude is varied can be transmitted over long distances requires complex equipment is preferred by music stations

Explanation:

AM (Amplitude Modulation) was developed in the 1870s, varies amplitude while frequency stays the same, can be transmitted long - distances, detected by simple equipment, and is used by news stations. FM (Frequency Modulation) was first used in the 1930s, varies frequency while amplitude stays the same, requires complex transmitters and receivers, is less susceptible to interference and noise, and is preferred by music stations.

Answer:

Was developed in the 1870s: AM, FM (empty)
Amplitude is varied: AM, FM (empty)
Can be transmitted over long distances: AM, FM (empty)
Requires complex equipment: AM (empty), FM
Is preferred by music stations: AM (empty), FM