Kundt’s Tube Apparatus
Holmarc's Kundt's tube apparatus (Model No: HO-ED-A-02) is a device for measuring the speed of sound. Any waves traveling along the medium will reflect back when they reach the end creating a standing wave allowing harmonics to be identified. Nodes occur at fixed ends and antinodes at open ends. Furthermore, it provides an insight into the interesting phenomenon of standing sound waves.
In this experiment the amplitude of the sound wave can be observed at different locations in the tube, allowing a half wave length to be measured between an adjacent maximum and minimum.
Here, one-side closed cylindrical transparent pipe filled with air is used as a resonator. One end of the tube is attached with a loudspeaker where as the other end is fixed with a movable piston with reflector and a microphone. An AC voltage applied to the loudspeaker, tunes the membrane to vibrations that are transferred to the gas or air column. Frequency can be changed by enlargement or diminishment of the glass cylinder as well as by changing the frequency of the generator.
Experiment:
To find the velocity of sound in air with the help of head phone
The velocity of the wave is,
V = ʋ λ
Where υ is the frequency and λ is the wavelength in the case of longitudinal waves, the wavelength is the difference between two consecutive compressions or rarefactions.
To find the velocity of sound in air using Lissajous Figures
A sine wave from an audio oscillator and the signal picked up by a movable microphone to produce Lissajous figures and determine the speed of sound.
Specifications:
| Transparent solid tube, 59 mm dia x 1000 mm long |
| End housing fixed with 2” speaker for creating the sound waves |
| Piston on a long rod to create variable length closed tubes |
| Driver unit to interface the microphone to an amplifier or oscilloscope |
Features:
| The scale can be rotated and positioned (for measuring the microphone position) |
| The parts can be easily removed from the tube and re-packed for storage in the classroom |
| The microphone is sensitive and strong |
| The piston fits in the tube with close tolerance. The piston supporting rod is made of brass |
Schematic:
Video:
Click HERE for Video
Related Topics:
| Longitudinal waves |
| Sound velocity |
| Frequency |
| Wave length |
| Stationary waves |
| Natural vibrations |