Question

In a Quincke's experiment, the sound detected is changed from a maximum to minimum when the sliding tube is moved through a distance of 2.50 cm. Find the frequency of sound if the speed of sound in air is 340 m/s.

Answer 1

Answer ⇒ 3.4 kHz.

Explanation ⇒ Given, that the displacement in the tube is 2.50 cm.

Thus, when the tube is moved by 2.50 cm the path length changes to 2 × 2.50 cm

= 5.0 cm.  

Since sound detected changes from maximum to minimum the waves interfere is destructive.

Now, for the consecutive maximum and minimum the phase difference is the least odd multiple of π i.e. π. (3π, 5π are higher thus will not be taken.)

So,

ΔΦ = 2πΔx/

π  = 2π  × 5/

= 10 cm

∴ = 0.10 m

Hence the frequency of the sound  

ν = V/

∴ fre. = 340/0.10 Hz

∴ frequency = 3.4 kHz

Hope it helps.

Answer 2

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