Question

The correct figure that shows, schematically, the wave pattern produced by superposition of two waves of frequencies $9 \,Hz$ and $11\, Hz$ is :

• A.
• B.
• C.
• D.

Answer 1

Answer: (D)

Answer 2

$f_{beat} = 11 - 9 = 2 \; Hz$
$\therefore$ Time period of oscillation of amplitude
$= \frac{1}{f_{beat}} = \frac{1}{2} Hz$
Although the graph of oscillation is not given, the equation of envelope is given by option