Physics Quiz 1

Distance and circumfrence is measured in?

feet, meters, inches

Area is measured in?

square feet

Volume is measured in?

cubes (^3)

What the tissue is doing to the sound wave?

acoustic propagation properties

Must have one of these three things to be a sound wave.

acoustical variables (pressure, density, distance)

Acoustical variables must be happening?

rhythmically

The three acoustical variables?

Pressure (Pretty)

Density (Dang)

Distance (Dumb)

Concentration of force within an area?

pressure

Pressure is measured in?

pascals (Pa)

Concentration of mass within a volume (^3)?

density

Unit of desity?

kg/cm^3

Measure of particle motion?

distance

Sound is ____________ energy.

mechanical (longitudinal)

Sound is comprised of?

compressions & rarefractions

Areas of increased pressure and density?

compressions

Areas that have decreased pressure and density?

rarefractions

Sound only travels?

in a straight line

Particles moving perpendicular to the direction of the wave?

transverse wave

Particles moving parallel to the direction of the wave?

longitudinal wave

The time it takes to complete a single cycle?

period

Unit of a period?

microseconds

Typical values of a period?

0\.06-0.5 microseconds

A period is determined by the?

sound source (p)

Can a sonographer change the period?

No (p)

The number of cycles of an acoustic variable that occur in one second?

frequency

Unit of frequency?

per second (hertz)

Typical values of frequency?

2-15 MHz

Frequency is determined by the?

sound source (f)

Can a sonographer change the frequency?

No (f)

Smaller frequency =

more penetration

How are frequency and period related?

inversely

Period and frequency are?

reciprocals

Period = 1/frequency

Frequency = 1/period

High frequency =

low period

High period =

low frequency

Anything greater than 20,000 Hz is classified as?

ultrasound

Anything between 20-20,000 Hz is classified as?

audible sound

Anything below 20 Hz is classified as?

infrasound

Define amplitude

the difference between the average value and the maximum or minimum value of an acoustic variable

Unit of amplitude?

decibels (dB)

Amplitude is determined by?

sound source (initially) (a)

Can amplitude be changed by the sonographer?

yes (a)

Peak-to-Peak amplitude

the difference between the maximum & minimum values in an acoustic variable

The rate at which work is performed or the rate of energy transfer

power

Unit of power?

watts (W)

Power is determined by the?

sound source (initially) (pr)

Can power be changed by the sonographer?

yes (pr)

Power is __________ to amplitude squared.

proportional

P= (A)^2

Concentration of energy in a sound beam?

intensity

Unit of intensity?

W/cm^2 (power/beam area)

Intensity and power are?

proportional

Typical values of intensity?

0\.001-100 W/cm^2

Intensity is determined by the?

sound source (initally) (i)

Can intensity be changed by the sonographer?

Yes (i)

Intensity is proportional to

amplitude squared

I= (A)^2

As amplitude goes up by 4, intensity ______

goes up by 16

Audible sound range

20-20,000 Hz

Audible sound = _________ kHz

0\.02-20 kHz

Below ______ Hz is infrasound.

20 Hz

Intensity = ______ /______

power/beam area