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Physics Test #1

PHYSICS TEST #1

QuestionAnswer
SPECULAR REFLECTIONS MIRROR LIKE REFLECTIONS, REFLECTED BACK IN THE SAME ANGLE AS THE INCIDENT ANGLE, OR ORIGINAL ANGLE.OCCUR WHEN: 1. WL IS SMALLER THAN BOUNDARY. 2. THE BOUNDARY IS SMOOTH.
NON-SPECULAR (DIFFUSE)REFLECTIONS SOUND REFLECTED BACK IN MANY ANGLES RATHER THAN JUST ORIGINAL ANGLE LIKE WITH SPECULAR REFLECTION.OCCURS WHEN WL IS LARGER THAN BOUNDARY 2. THE BOUNDARY IS NOT SMOOTH.
REFRACTION CHANGE IN DIRECTION OF THE SOUND WAVE DUE TO A CHANGE IN ITS PROPAGATION SPEED. DUE TO CHANGE IN MEDIUM.
ATTENUATION WEAKENING OF A SOUND BEAM AS IT PROPAGATES 1. ABSORPTION (GREATEST) 2.REFLECTION 3. SCATTERING
ATTENUATION COEFFICIENT AMT OF ATTENUATION PER CM OR PATH LENGTH. 3dB = .5 or 50%-10dB = .1 or 10%-20db = .01 or 1%
WAVELENGTH THE LENGTH OF SPACE 1 CYCLE TAKES UP.
DUTY FACTOR AMOUNT OF TIME PW IS ACTUALLY ON. UNIT LESS. EXPRESSED IN # OR %
PROPAGATION SPEED SPEED AT WHICH A SOUND WAVES TRAVELS THRU A MEDIUM. ONLY DEPENDENT ON THE MEDIUM.
SHEAR WAVES PARTICLE MOTION RUNS PERPENDICULAR TO NORMAL VALUE.
LONGITUDINAL WAVE PARTICLE MOTION RUNS PARALLEL TO NORMAL VALUE
RANGE OF FREQUENCIES 2-15 MHZ BELOW OR ABOVE RESOLUTION IS TOO POOR
PERIOD TIME FOR ONE CYCLE TO OCCUR
FREQUENCY # OF COMPLETE CYCLES PER SEC
DECIBEL ATTENUATION UNIT UNIT OF COMPARISON
INTENSITIES SATA (LOWEST) SPTP (HIGHEST) SPTA (MACHINE) THE BIGGER THE SOUND WAVE, THE STRONGER IT IS.
RANGE EQUATION DISTANCE THE MEDIUM IS FROM THE TRANSDUCER. NEED: DISTANCE AND DIRECTION
RAYLEIGH SCATTERING OCCURS WHEN PARTICLES ARE SMALLER THAN THE WAVELENGTH HITTING THE BOUNDARY.THE INTENSITY OF THE SCATTERED SOUND DEPENDS ON THE FREQ TO THE 4TH POWER. IF THERE IS AN INCREASE IN FREQ, THEN THERE IS AN INCREaSE IN SCATTER.
CW VS. PW PW IS PULSES OF SOUND WAVES VERSES ONE CONTINUOUS SOUND WAVE.
ACOUSTIC VARIABLES DENSITY (KG/M3), PARTICLE MOTION (MM), PRESSURE (Pa), & TEMP (DEGREES)
NORMAL INCIDENCE SOUND HITS BOUNDARY AT A 90 DEGREE ANGLE
OBLIQUE INCIDENCE SOUND HITS BOUNDARY AT ANY OTHER ANGLE THAN 90 DEGREES.
DENSITY Kg/m3 THE CONCENTRATION OF MATTER
SNELL'S LAW (LAW OF REFRACTION) WHEN WAVE HITS A DIFFERENT MEDIUM THAT HAS A DIFFERENT PS MAKES THE SOUND WAVE CHANGE SHAPE.
SCATTERING THE REDIRECTION OF SOUND IN MAY DIRECTIONS BY: ROUGH SURFACES, HETEROGENEOUS MEDIA (EX. BLOOD)
BACKSCATTER SCATTERED SOUND THAT GETS BACK TO THE TRANSDUCER.
IMPORTANCE OF SCATTERING IT ALLOWS THE TISSUE PARENCHYMA AND TISSUE INTERFACE TO BE SEEN. HELPS TO MAKE IMAGING LESS DEPENDENT ON SCANNING ANGLE.
MEGA MILLION
MILLI THOUSANDS
PROPAGATION SPEEDS SOFT TISSUE 1540M/S OR 1.54MM/US AIR 331 M/S BONE 3-4,000 M/S
TYPICAL DUTY FACTORS 0.1% OR 1.0%
ACOUSTIC IMPEDANCE THE EFFECT THE SOUND HAS ON THE MEDIUM. Z=DENSITY (KG/M3) X PS(M/S)
UNITS PRESSURE (Pa) DENSITY (Kg/m3) TEMP (DEGREES) PARTICLE MOTION (MM)
POWER THE RATE AT WHICH ENERGY IS TRANSFERRED.
PRF (KHz) pulsed rep freq. # of pulses occuring in 1 sec.
PRP (MILLISECONDS) PULSE REP PERIOD THE TIME FROM BEGIN OF ONE PULSE TO BEGIN OF NEXT PULSE.
DF (UNIT-LESS) DUTY FACTOR FRACTION OF TIME PW IS ACTUALLY ON.
PD (MICROSECONDS) PULSED DURATION TIME IT TAKES FOR ONE PULSE TO OCCUR
SPL SPATIAL PULSE LENGTH THE SPACE ONE COMPLETE PULSE TAKES UP.
IMPEDANCE FORMULA
PERIOD FORMULA
WAVELENGTH FORMULA
PRP FORMULA
ACOUSTIC IMPEDANCE FORMULA
4 STEP FORMULA
INTENSITY FORMULAS
DECIBELS
Created by: holly9610