MCQ Detailed View

Television (TV) signals are transmitted using electromagnetic waves, which carry both video and audio information. While the video signals are usually amplitude modulated (AM) to carry picture information, the audio signals of TV are frequency modulated (FM).

Frequency modulation (FM) works by varying the frequency of the carrier wave according to the instantaneous amplitude of the audio signal. This method offers several advantages for sound transmission:

1. 
   

   High noise immunity: FM is less affected by electrical noise and interference compared to AM. This ensures clearer audio quality for TV viewers.

   
   


2. 
   

   Better sound quality: FM provides a wider bandwidth, which allows for higher fidelity sound reproduction, making TV audio sound crisp and natural.

   
   


3. 
   

   Consistency over distance: FM audio signals maintain their quality better over moderate distances, which is important for broadcast systems.

   
   

Other options are incorrect:

• 
  

  Amplitude modulation (AM, Option 1) is used for TV video signals, not audio, because AM is more sensitive to noise for sound signals.

  
  


• 
  

  Fixed modulation (Option 3) is not a standard type of modulation.

  
  


• 
  

  Velocity modulation (Option 4) is used in certain electron tube applications, like klystrons, not for TV audio.

  
  

In a typical TV broadcast, the audio signal is first processed and amplified, then frequency-modulated onto a carrier wave before transmission. At the receiving end, the TV’s tuner separates the audio FM signal from the composite signal, and the demodulator extracts the audio, which is sent to speakers.Understanding that TV audio uses FM helps students link physics concepts of wave modulation to practical technology, such as television and radio broadcasting.

In conclusion, the audio signals of a TV are frequency modulated (Option 2) to provide clear, high-quality sound for viewers.