Question

use the text to compare and contrast fm and am.
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.

Explanation:

• For "Was developed in the 1870s": The text states "AM... Developed in the 1870s", so AM should be checked.
• For "Amplitude is varied": The text says "AM... works by varying the amplitude of a radio signal", so AM should be checked.
• For "Can be transmitted over long distances": The text mentions "AM radio can be transmitted over long distances", so AM should be checked.
• For "Requires complex equipment": The text says "FM requires complex transmitters and receivers", so FM should be checked.
• For "Is preferred by music stations": The text states "most music stations prefer FM", so FM should be checked.

Answer:

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