Question

A tuning fork of frequency 440 Hz resonates with a tube closed at one end of length 1.8 cm and diameter 5 cm in fundamental mode. The velocity of sound in air is

• A. 336 m s–1
• B. 343 m s–1
• C. 300 m s–1
• D. 350 m s–1

Answer 1

Answer: (B)

343 m s–1

Answer 2

In the fundamental mode of vibrations.

$(l + 0.3D) = \frac{\lambda}{4} = \frac{v}{4\upsilon}$

$\therefore v = 4\upsilon(l + 0.3D)$

$= 4 \times 440(0.18 + 0.3 \times 0.05)$

V = 343m $s^{- 1}$