Using this instrument several Ph.D. Thesis are awarded and innumerable Research papers are published in National & International Journals. Velocity measurement combining with other physical quantities provides information of more than 30 Parameters. For ready reference few Equations are listed here. Few Experiments are also suggested for laboratory purpose.
The principle used in the measurement of velocity (ν) is based on the accurate determination of the wavelength (λ) in the medium. Ultrasonic waves of known frequency (f) are produced by a quartz crystal fixed at the bottom of the cell. These waves are reflected by a movable metallic plate kept parallel to the quartz crystal. If the separation between these two plates is exactly a whole multiple of the sound wavelength, standing waves are formed in the medium. This acoustic resonance gives rise to an electrical reaction on the generator driving the quartz crystal and the anode current of the generator becomes a maximum.
If the distance is now increased or decreased, and the variation is exactly one-half wavelength (λ /2), or multiple of it, anode current becomes maximum. From the knowledge of wavelength ( λ ) the velocity (v) can be obtained by the relation: Velocity = Wavelength x Frequency
v = λ x f
The Ultrasonic Interferometer consists of the following parts:
HIGH FREQUENCY GENERATOR
Single and Multi-frequency
Max. displacement of the reflector : 20 mm Required Quantity of liquid: 10 c.c. Least Count of micrometer: 0.01mm/0.001 mm
Impedance : 50 O
Optional: If the variation in the velocity with temperature is to be studied, water at various desired constant temperatures is made to circulate through the double walled jacket of the cell with external circulating water bath.
A number of parameters related to ultrasonic velocity are:
Effective Debye Temperature
Intermolecular Free Length
Solvation Number/ Hydration Number
Vander Wall's Constant
Proton Relaxation Rate
Relaxation Time and Relaxation Strength
Space Filling Factor
Cohesive Energy Barrier
Latent Heat Of Vaporization
Specific Heat Ratio
Miscibility and Compatibility of Blends and many more