US Physics Wk 2 Exam

units for period

seconds (any form of time)

units for frequency

hertz (Hz)

units for amplitude

Pa, cm, dB, g/cm^3

*any of the 3 variables*

units for power

Watts (W)

units for intensity

W/cm²

units for wavelength

meters (m)

*any form of distance*

units for speed

meters per second (m/s)

units for pulse duration

microseconds

*units of time*

units for PRP

msec

*any unit of time*

units for PRF

hertz (Hz)

units for spatial pulse length

mm

*any unit of distance*

units for duty factor

%

_______ waves cannot create anatomic images

continuous

a collection of cycles that travels together

a pulse

2 components that make up pulsed US

transmit time and receive time

transmit time, AKA

talking

receive time, AKA

listening

- pulse duration

- pulse repetition period

- pulse repetition frequency

- duty factor

- spatial pulse length

parameters for pulsed US

the actual time from the start of a pulse to the end of that pulse

pulse duration

the "on" time or "talking" time of a single pulse

pulse duration

units for pulse duration

microseconds

typical values for pulse duration

0.3 - 2 microseconds

pulse duration is determined by _________ only

sound source

pulse duration ________ be changed by sonographer

cannot

pulse duration _______ change with depth

does not

pulse duration =

# cycles x period

pulse duration is _________ proportional to the number of cycles in the pulse

directly

pulse duration is _______ proportional to period

directly

pulse duration is _________ proportional to frequency

inversely

pulses with ______ duration are more desirable for imaging because they produce better images

shorter

the distance that a pulse occupies in space from the start to the end of a pulse

spatial pulse length

spatial pulse length is the same as which continuous wave parameter?

wavelength

units for spatial pulse length

mm (units of distance)

typical values for spatial pulse length

0.1 - 1 mm

spatial pulse length is determined by

both the sound source and the medium

spatial pulse length _______ be changed by sonographer

cannot

spatial pulse length =

# of cycles x wavelength

spatial pulse length is ______ proportional to frequency

inversely

spatial pulse length is the _______, while pulse duration is the ______

distance

time

if a pulse is short in time, it will be _____ in distance

short

- many cycles in the pulse

- cycles with longer wavelengths

create long pulses

- fewer cycles in the pulse

- cycles with shorter wavelengths

create short pulses

the time from the start of one pulse to the start of the next pulse, including one pulse duration and one listening time

pulse repetition period

units for PRP

milliseconds (units of time)

typical values for PRP

100 microseconds to 1 millisecond

PRP is generally about 100-1000 times longer than

pulse duration

PRP is determined by _________only

sound source

PRP ______ be changed by sonographer

can

how can you adjust PRP?

change image depth

describes the maximum distance into the body that an ultrasound system is imaging

depth

PRP and depth are ______ related

directly

when US is imaging more deeply, PRP

increases

(bc time from one pulse to next is longer)

when US imaging is at shallow depths, the PRP

decreases

two components of PRP

1. transmit time

2. receive time

the "on" time =

transmit time

transmit time represents

pulse duration

the "off" time =

receive time

the number of pulses than an US system transmits into the body each second

pulse repetition frequency

units for PRF

Hz

typical values for PRF

1,000 - 10,000 Hz

(1-10 kHz)

PRF is determined by _______ only

sound source

PRF ______ be changed by sonographer

can

PRF is _______ to frequency

unrelated!!

PRF is only related to

depth

PRF and depth are _______ related

inversely

shallow imaging = ______ PRF

higher

deeper imaging = ______ PRF

lower

PRP and PRF are ______ related

inversely

a longer PRP results in a ______ PRF

lower

PRP x PRF =

1

(bc they are reciprocals)

the percentage or fraction of time that the system transmits a pulse

duty factor

typical values for duty factor

0.2 - 0.5%

duty factor is determined by _________ only

sound source

duty factor _______ be changed by sonographer

can

duty factor is _______ related to depth

inversely

duty factor =

pulse duration/PRP x 100

maximum value for duty factor

1 or 100%

maximum value of duty factor is only achieved with ________ wave sound

continuous

minimum value for duty factor

0%

two terms that are not associated

unrelated

two items that are associated

*relationship does not have to be specified*

related or proportional

two items that are directly associated, such that when one item increases the other one will increase

directly relational/proportional

two items that are associated such that when one increases, the other decreases

inversely related/proportional

when two numbers of a reciprocal relationship are multiplied together, the result is

one

this is a special form of an inverse relationship

reciprocal

increase by a factor means to

multiply by that number

decrease by a factor means to

divide by that number

a number alone without a unit is called

ambiguous

- meter

- centimeter

- feet

units of length

- cm^2

- squared

units of area

- cm^3

- cubed

units of volume

a number written in scientific notation with a positive exponent has a value greater than

10

a number written in scientific notation with a negative exponent has a value less than

1

a number written in scientific notation with an exponent of zero has a value between

1-10

a traveling variation in one or more quantities

wave

2 types of waves:

longitudinal and transverse

wave where particles move in a direction that is perpendicular to the direction that the wave propagates

transverse wave

light is a _______ wave

transverse

wave where particles move in the same direction that the wave propagates

longitudinal wave