Question

Beats are heard due to interference of two sound waves. The intensity of sound changes from maximum to minimum in $100ms$. Therefore, the difference in frequencies of the two waves is

• A. $10Hz$
• B. $5Hz$
• C. $2.5Hz$
• D. $20Hz$

Answer 1

The correct option is B $5Hz$

Time interval in which the intensity changes from maximum to maximum again, $t=2\times 100=200$ ms

Thus, beat frequency, $b=|{\nu }_1-{\nu }_2|=\frac{1}{t}$

$⟹$ $b=\frac{1}{200\times {10}^{-3}}=5$ $Hz$