Ultrasound and its Applications

Ultrasound refers to sound waves with frequencies higher than 20,000 Hz, which is above the upper limit of human hearing.

Properties of Ultrasound:

• • They are longitudinal waves like ordinary sound.
  • They can travel through solids, liquids, and gases but need a medium (cannot travel in vacuum).
  • They have very high frequency and short wavelength.
  • They can be reflected, refracted, and focused just like light.

Applications of Ultrasound

1. Medical Imaging (Ultrasound Scanning):

• • Used to view internal organs and tissues of the body (e.g., liver, kidneys, heart).
  • Commonly used in prenatal scanning to observe the fetus safely, since ultrasound is non-ionizing (unlike X-rays).
  • Works by sending pulses of ultrasound into the body → echoes are reflectFed back from tissue boundaries → computer forms an image.

2. Industrial Applications:FF

• • Non-destructive testing (NDT): Detects cracks or faults in metal structures (e.g., aircraft wings, bridges, machinery parts).
  • Cleaning: Used to clean delicate objects like jewelry, watches, and electronic components. High-frequency vibrations shake off dirt particles.

3. Navigation and Ranging (SONAR):

• • SONAR = Sound Navigation and Ranging.
  • Ships and submarines send ultrasound pulses into water → measure the time taken for echo to return → calculate depth or detect obstacles.

Depth = \( \dfrac{v \times t}{2} \)

• • Where \(v\) = speed of sound in water, \(t\) = time for pulse to return.