Chap 3 (edelman)- Describing Sound Waves

What is the period of earths rotation around the sun?

1 yr

A top is spinning on a table. What is the period of the spinning top?

0.05 seconds

Which of the following waves is infrasonic ?

2 Hz

Identify the wave that is ultrasonic?

4 MHz

Which of these waves is ultrasonic and most useful in diagnostic sonography?

4M MHz

identify all of the waves that are inaudible (more than 1 answer is correct)

a. 4 MHz

b. 400 kHz

c. 28 Hz

d. 2 Hz

a, b, d

Which of the following waves has the longest period?

6 Hz

Of the four waves whose periods are listed below, which has the highest frequency?

80 microseconds

Of the four waves whose periods are listed blow, which has the highest frequency?

12 kHz

Of the four waves whose periods are listed below, which has the lowest frequency?

8 Ms

Units for wavelength

millimeters

Units for frequency

hertz

Units for intensity

watts/cm²

Units for propagation speed

meters/second

Units for period

second

Units for power

watts

does the medium or the sound source determine wavelength?

does the medium or the sound source determine intensity (initial)

sound source only

does the medium or the sound source determine propagation speed

does the medium or the sound source determine period

sound source only

does the medium or the sound source determine power (initial)

sound source only

does the medium or the sound source determine amplitude (initial)

sound source only

Using a particular US system and transducer, which of the following cannot be changed by the operator?

• wavelength

• frequency

• intensity

• propagation speed

• period

• power

• amplitude (initial)

wavelength, frequency, propagation speed, and period

Know how to label a wave

know how to label a wave

True or False. If the power of a wave is halved, the intensity is reduced to one0fourth its original value.

False

True or False. Propagation speed increases as frequency increases.

False

Medium 1 has a density of 9 and a stiffness of 6. Medium 2 has a density of 8 and a stiffness of 6. In which medius will sound travel slower?

Medium 1 (same stiffness, so greater density will have lower propagation speed)

Which of the following characteristics will create the fastest speed of sound?

a. high density, high stiffness

b. low density, high stiffness

c. high density, low stiffness

d. low density, low stiffness

B (speed inversely proportional to density and directly proportional to stiffness)

Which of the following characteristics will create the slowest speed of sound?

a. high density, high stiffness

b. low density, high stiffness

c. high density, low stiffness

d. low density, low stiffness

C (stiffness is inversely proportional to density and directly proportional to stiffness)

If the power in a beam is 1 watt and the area is 5cm², what is the beams intensity?

0.2 W/cm²

If intensity remains the same while the power is doubled what happens to the beam area?

doubled

a sound beam travels a total of 10cm in 2 seconds. What is the speed of the sound?

5cm/sec

True or False. Propagation speed increases as frequency increases.

False.

True or False. Propagation speed increases as frequency decreases.

False.

True or False. Propagation speed does not change as frequency increases.

True.

What is the wavelnegth of 3 MHz of sound in s

What is the wavelength of a wave with an unknown frequency traveling in soft tissue?

0.51mm (due to units)

The effects of sound waves on tissue in the body are called _____

bioeffects

Which of the following are considered acoustic variablels?

a. frq

The effects of tissue on sound waves are called _____

acoustic propagation properties

How are power and intensity related?

How are wavelength and intensity related?

unrelated

How are wavelength and frequency realted?

How are elasticity and speed of sound related?

inversely

How is acoustic velocity and compressibility related?

inversely

How is stiffness and sound speed related?

directly

How is frequency and sound speed related?

unrelated

How is frequency and intensity related?

Unrelated

How is power and frequency related?

unrelated