A tuning fork vibrates with frequency $256\, Hz$ and gives one beat per second with the third normal mode of vibration of an open pipe. What is the length of the pipe ? (Speed of sound in air is $340\, ms^{-1}$)
- 220 cm
- 190 cm
- 180 cm
- 200 cm
The Correct Option is D
Solution and Explanation
It gives one beat per second with the third normal mode of vibration of an open pipe.
Therefore, frequency of open pipe $=(256+1) Hz$
Speed of sound in air is $340 m / s$.
Now we know, frequency of third normal mode of vibration of an open pipe is given as
$f=\frac{3 v_{\text {sound }}}{2 l}$
$\Rightarrow \frac{3 \times 340}{2 l}=255$
$\Rightarrow l=\frac{3 \times 340}{2 \times 255}=2\, m =200\, cm$
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Concepts Used:
Waves
Waves are a disturbance through which the energy travels from one point to another. Most acquainted are surface waves that tour on the water, but sound, mild, and the movement of subatomic particles all exhibit wavelike properties. inside the most effective waves, the disturbance oscillates periodically (see periodic movement) with a set frequency and wavelength.
Types of Waves:
Transverse Waves -
Waves in which the medium moves at right angles to the direction of the wave.
Examples of transverse waves:
- Water waves (ripples of gravity waves, not sound through water)
- Light waves
- S-wave earthquake waves
- Stringed instruments
- Torsion wave
The high point of a transverse wave is a crest. The low part is a trough.
Longitudinal Wave -
A longitudinal wave has the movement of the particles in the medium in the same dimension as the direction of movement of the wave.
Examples of longitudinal waves:
- Sound waves
- P-type earthquake waves
- Compression wave