Question

A turning fork with frequency 800 Hz produces resonance in a resonance column tube with upper end open and lower end closed by water surface. Successive resonances are observed at length 9.75 cm, 31.25 cm and 52.75 cm. The speed of sound in air is

(a) 500 m/s

(b) 156 m/s

(c) 344 m/s

(d) 172 m/s

Answer 1

Correct option is : (c) 344 m/s

v = 800 Hz

v = 2v (l₂ - l₁)

l₁ = 9.75 cm, l₂ = 31.25 cm

∴ v = 2 x 800 (31.25 - 9.75)

= 344 m/s