Question

In a resonance tube experiment at one end, resonance is obtained at two consecutive lengths \(l_1 = 100\ cm\) and \(l_2 = 140 \ cm\). If the frequency of the sound is 400 Hz, the velocity of sound is 

(1) 320 m/s 

(2) 340 m/s 

(3) 380 m/s 

(4) 300 m/s 

Answer 1

Correct option is: (1) 320 m/s 

\(\Delta l = \frac{\lambda}{2}\)

\(\lambda = 2 \times 40 = 80 \ cm\)

\(v= f\lambda= \frac{400 \times 80}{100} = 320 \ m/s\)