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Introduction | Ultrasonic

 Ultrasonic waves

Definition

The sound waves of frequency greater than 20kHz are called ultrasonics waves. These sound waves are inaudible to human ear. The ultrasonic waves due to their shorter wavelength have a greater penetrating power.

Ultrasonic waves are widely used in medical diagnostics, marine applications, NDT, etc.


Properties of Ultrasonic waves

  1. The frequency of ultrasonic waves is greater than 20 kHz.
  2. Their wavelength are small. As a result, their penetrating power is high.
  3. They can travel over long distances as a high directional beam.
  4. They have high energy content.
  5. Their speed of propagation increases with increase in frequency.

Production of Ultrasonic waves 

Based on frequency range and power output, the ultrasonic waves generators divided into two groups:
  1. Mechanical generator
  2. Electrical generator

The electrical generator are subdivided into two categories:
  1. Megnetostriction generator or oscillator
  2. Piezoelectric generator or oscillator

Above two electrical generation methods are widely used nowadays for producing ultrasonic waves.

Presense of ultrasonic waves can be detected by using one of the following methods:
  1. Quartz crystal method
  2. Thermal detection method
  3. Sensitive flame method
  4. Mindy's tube method

Applications of Ultrasonic waves

It is based on the principle of echo sounding.
  1. Determination of depth of sea
  2. Cavitation
  3. Ultrasonic cleaning
  4. Ultrasonic drilling and cutting
  5. Ultrasonic welding (cold welding)
  6. Ultrasonic soldering
  7. Medicine
  8. Science and technology




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