Ultrasound Physics Exam 1

What is stiffness

resistance to deformation

What is the unit of power

Watt

What are the units for intensity

power per area (W/m^2)

What are the bigness parameters

Amplitude, power and intensity

What happens when a decibel is positive

it increases the amplitude

What is the sound propagation speed

how long it takes a wave to travel a distance during a time (m/s)

What factors determine the frequency of a sound wave

wavelength propagation speed and the thickness of the material

What is wave superposition

When 2 waves run together

What is acoustic impedance

acoustic resistance to sound traveling in a medium

What unit measures acoustic impedance

rayls (Z)

What determines the frequency?

The source

How many dimensions does a longitudinal wave move in?

Two

How many dimensions does a transverse wave move in?

Three

How do the particles in a longitudinal wave move?

parallel to the wave

How do particles in a transverse wave move?

perpendicular to the wave

What type of wave is used in an ultrasound

longitudinal

What is wavelength

Length of the wave (distance)

What is frequency

How many cycles per second

What is the period

Length of the wave (time)

How are wavelength and frequency related

inversely

How are frequency and period related?

Inversely

Does sound carry better in stiff or dense medium

stiff

what is the unit for density

mass per volume (g/cm^3)

What variable represents density

Rho

What variable represents stiffness

B

What variable represents period

T

What variable represents wavelength

Lambda

What is power

rate of energy transfer

What is intensity

concentration of energy in a sound beam

What determines intensity

source

What variable represents amplitude

A

What variable represents intensity

I

What variable represents power

P

What is the unit for amplitude

Pascals (Pa)

What is a decibel

logarithmic method of finding a ratio between 2 amplitudes

What is the opposite of Mega

micro

What prefix is the power of 6

Mega

What is the prefix for the power of 3

kilo

What is the prefix for the power of -3

milli

What is the prefix for the power of 2

hecto

What is the formula for volume of a prolate ellipse object

lwh*0.523

What kind of pressure and density is compression

high

What is the period if the frequency is 3MHz

0.33 microseconds

What does wavelength depend on

frequency

What are the acoustic variables

pressure

What happens to the pulse duration when the frequency increases

It becomes shorter

What is the speed of sound in soft tissue

1540 m/s

What is the range for diagnostic ultrasound

2MHz - 20MHz

What is the amplitude

height of a wave from the mid-line

What is the pulse average (PA)

average intensity during the pulse

What is the speed of sound in air

330m/s

what is another word for average

mean

How are wavelength and period related

directly

What is another name for stiffness

Bulk

What does high bulk mean for its compressibility

low compressibility

What does low bulk mean for its compressibility

high compressibility

how are density and speed of sound related

inversely

how are stiffness and speed of sound related

directly

What variable represents frequency

f

what determines power

source

What is the relationship between intensity and area

inversely

What is the relationship between intensity and power

directly

What variable represents area

a

When is amplitude proportional to intensity and power

when it is squared

What happens when a decibel is negative

It decreases the amplitude

What is the relationship between amplification and gain

amplitude control=gain control

What's the opposite of Giga

nano

What prefix is the power of 9

Giga

What prefix is the power of -9

nano

What prefix is the power of -6

micro

What is the opposite of kilo

milli

What is the opposite of hecto

centi

What is the prefix for the power of -2

centi

What is the opposite of deca

deci

What is the prefix for the power of 1

deca

What is the prefix for the power of -1

deci

What is the distance

How far

What is the formula for volume

(4/3)pi*r^3

What kind of pressure and density is rarefaction

low

What determines the period

source

What happens to sound propagation in different media

The speed changes

What is wavelength*frequency

speed of sound

What is the range for infrasound

less than 20Hz

What is the range for audible sound

20Hz - 20

What is the range for ultrasound?

greater than 20kHz

What determines the amplitude

source

What is the pulse duration

the time the transducer generates sound

What is constructive interference?

2 waves are "in-phase" and are added together to create a more powerful wave

What is destructive interference?

2 waves are "out of phase" and are added together to create a less powerful wave

What part of the wave is an antinode

the crests and troughs

What part of the wave is a node

the intersections of the mid-line

What is the 3 dB rule?

Every 3 dB change is a multiplication or division by 2

What is the temporal average (TA)

average intensity of the ultrasound beam

What is the temporal peak intensity (TP)

the maximum intensity of the ultrasound wave

What is the intensity maximum (IM)

average intensity during the most intense half cycle

What is the spatial peak intensity (SP)

intensity at the location where the wave is at it's maximum

What temporal and spatial combination has the highest value?

SPTP

What is a Hertz (HZ)

1/s

What is the speed of sound in bone?

3500m/s or 4080m/s

What is the speed of sound in fat

1450m/s