초음파 SPI 기초물리 및 기초원리4

1. Acoustic Waves
1) Traveling variation (oscillation) in acoustic variables
- Molecules oscillate back and forth to propagate sound waves
- Do not move from one end of the medium to another
- Acoustic variables
: Temperature
: Pressure - Concentration of force in an area
: Density - Concentration of mass in a volume
: Distance - Measure of particle moon
2) Mechanical longitudinal wave
3) Vacuum: a space void of matter
- Sound cannot travel in a vacuum
- Electromagnetic radiation, light/x-ray can travel through a vacuum
2. Mechanical Waves
1) require a medium for propagation (gas, liquid, or solid)
- cause motion of the particles they are moving through
- molecules do not travel from one end to the other (it is not a flow of particles).
: Molecules vibrate back and forth
- can be either Transverse or longitudinal.
2) Longitudinal Waves
- particles of medium vibrating in the same direction as the wave propagation direction
- sound: mechanical longitudinal wave
3) Transverse Waves/Shear Waves/Stress Waves
- propagates by particles of the medium moving perpendicular to the wave propagation direction.
- Bone: The only biological tissue that can cause the production of transverse waves