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Ultrasonic Interferometer For Liquids
The principle used in the measurement of velocity (Î½) is based on the accurate determination of the wavelength (Î») 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 ( Î» /2), or multiple of it, anode current becomes maximum. From the knowledge of wavelength ( Î» ) the velocity (v) can be obtained by the relation: Velocity = Wavelength x Frequency
v = Î» x f
The Ultrasonic Interferometer consists of the following parts:
HIGH FREQUENCY GENERATOR Single and Multi-frequency
MEASURING CELL Max. displacement of the reflector : 20 mm Required Quantity of liquid: 10 c.c.
Least Count of micrometer: 0.01mm/0.001 mm
SHIELDED CABLE Impedance : 50 O