6. Sound Waves Flashcards
Sound
What it is + How it is produced
Sound is a longitudinal wave (direction of vibration is parallel to the direction of wave propagation) produced by a vibrating source:
- Cannot travel through a vacuum
- Needs a medium to propagate (fastest in solid, slowest in gas)
- Medium particles are not transported away from the source
How is sound propagated?
The forward and backward vibration of a source is passed on to the air/water particles. This causes alternate regions of the air particles to be compressed and extended, resulting in a series of compressions and rarefactions.
- Compressed regions are called compressions (higher pressure)
- Extended regions are called rarefactions (lower pressure)
Wavelength of Longitudinal Wave
Definition
The wavelength of a longitudinal wave is the distance between the centres of two successive compressions or rarefactions
Pitch of sound is affected by
Frequency of the sound wave
Loudness of sound is affected by
Amplitude of the sound wave
Ultrasound is used in
- Sonar (Sound Navigation And Ranging)
- Strength of reflected pulse depends on distance and characteristics of reflecting objects
- Imaging Internal organs
- Strength, direction, timing of reflected pulse are measured to allow the reflecting surface to be mapped
- Pre-natal scanning
- Breaking up kidney stones
- Cancer treatment