A carrier wave of frequency $f_c=10\text{ MHz}$ is modulated by a signal of frequency $f_m=5\text{ kHz}$. What are the frequencies of the sidebands produced?

Solution

1. Identify the given frequencies: carrier frequency $f_c=10\text{ MHz}$ and modulating frequency $$\begin{array}{rl}{f}_m& =5\text{ kHz}\\ & =0.005\text{ MHz}\end{array}$$.
2. The sideband frequencies are given by the formula $f_{sidebands}=f_c\pm f_m$.
3. Calculate the upper sideband: $10\text{ MHz}+0.005\text{ MHz}=10.005\text{ MHz}$.
4. Calculate the lower sideband: $10\text{ MHz}-0.005\text{ MHz}=9.995\text{ MHz}$.
5. Hence the answer is (A).