When the wavelength of sound changes from 1 m to 1.01 m,

When the wavelength of sound changes from 1 m to 1.01 m, the number of beats heard are 4. The velocity of sound is

(a) 400 m/s
(b) 300 m/s
(c) 404 m/s
(d) 100 m/s

404 m/s

v = ʋλ ⇒ Now, v = ʋ × 1

v = 1.01 × ʋ’ Also ʋ’ = (ʋ – 4)

So, ʋ × 1 = 1.01 × (ʋ – 4)

⇒ 1.01ʋ – ʋ = 1.01 × 4

0.01ʋ = 1.01 × 4

⇒ ʋ = 404 Hz

v = ʋλ

= 404 × 1 = 404 m/s

OA2007

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