Ch. 3 Physics: Describing sound waves Flashcards by iliana rushlow

What is the source of a sound wave?

The ultrasound system and the transducer

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What is considered the medium which sound travels through?

Body Tissue, Gel, or the organs

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What is the time from the start of one cycle to the start of the next?

Period

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What is the units of mesurement for period?

Millisecond
seconds

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What is the typical value for period?

.06 to .5 microseconds

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What is the period determined by?

The sound source

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Is the period adjustable or not adjustable by the sonographer?

Not adjustable

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What is the number of complete cycles in one second?

Frequency

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What is the unit of measurements for Frequency?

Hertz (Hz)

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What is the clinical value range for frequency?

2 to 15 MHz

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What is frequency determined by?

the Sound source

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Is the frequency adjustable or not adjustable by the sonographer?

Not adjustable

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What is the sound frequency for audible sound?

20Hz to 20kHz

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What is the sound frequency for infrasound?

below 20Hz

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What is the sound frequency for ultrasound?

Greater than 20kHz

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True or False:
Frequency of sound is clinically important since it affects penetration and image quality.

True

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What produces better image quality?

Higher frequency, less penetration

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What produces lesser image quality?

Lower frequency, More penetration

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What is the relationship between period and frequency?

Inversely

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As frequency increases, what will happen to the period?

Will decrease

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As frequency decreases, what will happen to the period?

will increase

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What is the period of wave that has a frequency of 8Hz?

1/8 of a second

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What is the 3 bigness parameters?

Intensity
Power
Amplitude

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What can Amplitude also be expressed as?

Decibels (db)

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The "bigness" of a given wave either above the baseline or below the baseline.

Amplitude

Clinically, pressure amplitude ranges from what?

1 million pascals (1MPa) to 3 million pascals (3 MPa)

Amplitude is determined by what?

the sound source

True or False: Amplitude increases as it propagates through the body

False it decreases

How is amplitude measured?

from the baseline out to the peak.

Is amplitude adjustable or not adjustable by the sonographer?

Adjustable

The ratee of energy transfer, or the rate at which work is done is called what?

Power

What is the unit of measure for power?

watts

Clinically, what is the imaging values range for power?

0.004 to 0.090 watts

What is power determined by?

the sound source

Does power decrease or increase as it propagates through the body?

Decrease

Is power adjustable or not adjustable by the sonographer?

Adjustable

True or False: Power is affected by the density of the medium

True

What is the relationship of power and amplitude?

Directly related or directly proportional

When power increases, what happens to the amplitude?

it increases

When power decreases, what happens to the amplitude?

it decreases

What is the concentration of energy in a sound beam called?

Intensity

What are the units for intensity?

Watts/square centimeter (W/cm^2)

True or false: Intensity depends on the power of the beam and the area over which the power is applied.

True

What is the value range for intensity?

0.01 to 300 W/cm^2

What is instensity determined by?

the sound source

Intensity sound propagation chages depending on the characteristics of what?

Both the sound wave and the medium

Is intensity adjustable or not adjustable by the sonographer?

Adjustable

What is the relationship between intensity and power?

It is proportional

What is the relationship between intensity and amplitude?

it is proportional

If the power of a wave doubles, the intensity...

also doubles

If the power of a wave is cut in half, the intensity is....

also cut in half

Always remember that squared follows...

amplitude

The distance or length of one complete cycle is called

wavelength

What is the units of measure for wavelength?

mm, meters

Clinically, the wavelength in soft tissue ranges from...

0.15 to 0.8mm

what is the wavelength determined by?

Both source and medium

Is the wavelength adjustable or not adjustable by the sonographer?

Not adjustable

What is the relationship between wavelength and frequency?

inversely

In soft tissue, sound with a frequency of 1MHz has a wavelength of...

1.54mm

If the wavelength goes up, the frequency..

goes down

If frequnecy goes up, the wavelength..

goes down

How do you determine the wavelength in soft tissue?

Divide 1.54mm by the frequncy in MHz

What is the wavelength using a 1MHz transducer?

1.54mm

What is the wavelength using a 2MHz transducer?

.77mm

Higher frequency = _______ wavelengths

shorter

Lower frequency =________ wavelengths

longer

Which frequency will have better image quality?

High frequency

Which frequency will penetrate deeper?

Low frequency

What is the rate at which a sound wave travels through a medium called?

Propagation Speed

What is propagation speed measured in?

mm/s or distance/time

What is propagation speed dependent on?

Tissue

What is the speed range for propagation speed?

500 m/s to 4000 m/s

Propagation speed is determined only by what?

the medium

Is propagation speed adjustable or not adjustable by the sonographer?

Not adjustable

True or false: All sound travels at different speed

False travels at the same speed

What is the speed of sound in soft tissue?

1540 m/s or 1.54km/s or 1.54mm/µs

Does sound travel slow or fast in solids?

Fastest

Does sound travel slow or fast in liquids?

Slower

Does sound travel slow or fast in gasses?

Slowest

What are the 7 acoustic parameters?

Period Frequency Amplitude Power Intensity Wavelength Speed

What determines the speed of period and frequency?

Sound source

What determines the speed of amplitude, power and intensity?

Sound source

What determines the speed of wavelength?

sound source and medium

What determines speed?

Medium

What is the ability of an object to resist compression called?

Stiffness

What is directly related to speed?

Stiffness

What is another term for stiffness?

Bulk Modulus

What is the opposite of stiffness?

Elasticity and compressibility

What describes the relative weight of a material?

Density

True or false: Dense material wighs more than non-dense.

True

What is related to density?

Weight

What relationship do density and speed have?

inversely related