Amplitude modulated wave is represented by V _ AM = 10[1 + 0 . 4...

Expression for modulation is given by,

$s\left(t\right) = {A}_{c}\left[1 + \mu cos\left(2\pi{f}_{m}t\right)\right]\cos \left(2\pi{f}_{c}t\right)$, where ${f}_{m}$ and ${f}_{c}$ are the frequency of the modulating signal and the carrier signal respectively.

Comparing it with the given expression in question, we get,

${f}_{m} = {10}^{4}Hz$

Now, Bandwidth $= 2{f}_{m} = 20kHz$