Question

Standing waves are produced in a 10 m long stretched string. If the string vibrates in 5 segments and the wave velocity is 20 m/s, the frequency is :

• A. 10 Hz
• B. 5 Hz
• C. 4 Hz
• D. 2 Hz

Answer 1

Answer: (B)

In the case of standing wave, the length of one segment is $\frac{\lambda }{2}$ . There are 5 segments and total length of string is 10 m. $\therefore$ $5\frac{\lambda }{2}=10$ $\Rightarrow$ $\lambda =4m$ Frequency, $n=\frac{v}{\lambda }=\frac{20m/s}{4m}=5Hz$ NOTE: Standing wave is an example of interference. Destructive interference means node and constructive interference means antinode.