In amplitude modulation, the sinusoidal carrier frequency used is denoted by ${\omega }_c$ and the signal frequency is denoted by ${\omega }_m$ . The bandwidth $\left(\mathrm{\Delta }{\omega }_m\right)$ of the signal is such that $\mathrm{\Delta }{\omega }_m\ll {\omega }_c$. Which of the following frequencies is not contained in the modulated wave?

• A

  ${\omega }_c-{\omega }_m$
• Correct answer
  B

  ${\omega }_m$
   
• C

  ${\omega }_c$
• D

  ${\omega }_m+{\omega }_c$

Solution

$\because$ $\mathrm{\Delta }{\omega }_m\ll {\omega }_c$

${\omega }_m$ will not be there in the frequencies.

In modulated wave

Hence, the correct answer is option: 'B'.