Question

A tuning fork of frequency 250 Hz is vibrating at one end of a tube as shown in fig.If maximum sound is heard at the other end, the velocity of wave will be.....,​

Answer 1

A tuning fork of frequency 250 Hz is vibrating at one end of a tube as shown in fig.If maximum sound is heard at the other end, the velocity of wave will be

• Given,
• f = 250 Hz
• we use formula,
• $f = \dfrac{nv}{4l}$
• where, n = odd positive number
• Now,
• $f = \dfrac{nv}{4l_1}$
• $f = \dfrac{(n+2)v}{4l_2}$
• $f=\dfrac{(n+4)v}{4l_3}$
• $l_2 - l_1 = \dfrac{(n+2)v}{4f} - \dfrac{nv}{4f}$
• $=\dfrac{v}{2f}$
• $l_2-l_1 = l_3-l_2 = \dfrac{v}{2f}\\\\l_1 = 9.75\\\\l_2 = 31.25\\\\l_2-l_1 = 21.5\\\\l_3-l_2 = 21.5$
• $21.5 = \dfrac{v}{2*800}\\\\v = 344 m/s$