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DSM PHY > Physics 1 Test Ch 6, 7 > Flashcards

Physics 1 Test Ch 6, 7 Flashcards

1
Q

How is intensity calculated?

A

Power/area

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2
Q

What are the units for intensity?

A

W/cm^2

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3
Q

What are the names for normal incidence?

A 
Perpendicular
Orthogonal
Right angle
Normal
Ninety degrees
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4
Q

Any angle other than 90 degrees

A

Oblique

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5
Q

An acute angle is..

A

Less than 90 degrees

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6
Q

An obtuse angle is..

A

Greater than 90 degrees

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7
Q

intensity of sound wave at the instant prior to striking a boundary is called…

A

Incident intensity

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8
Q

the portion of incident intensity and reflected completly

A

Reflected intensity

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9
Q

normal incidence is what degree?

A

90 degrees

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10
Q

portion of incident intensity after striking boundary that continues?

A

Transmitted intensity

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11
Q

% of ultrasound intensity when sound strikes a boundary?

A

Intensity Reflection Coefficient (IRC)

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12
Q

% of ultrasound that is allowed to pass through?

A

Intensity Transmission Coefficient (ITC)

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13
Q

Intensity reflection coefficient and intensity transmission coefficient have what units?

A

No units

They are percentages

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14
Q

with normal incidence,reflection depends upon different what?

A

Different impedance

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15
Q

a large reflection will occur in normal incidence if impedance are what?

A

Substantially different

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16
Q

with greater impedance differences the IRC increases and the amount of reflection?

A

I found this information online I think…

reflection increases

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17
Q

specular reflections arise when the interface is…

A

Smooth

18
Q

The 2 physical principles always apply to oblique incidence

A

1) Conservation of energy

2) Reflection angle=incident angle

19
Q

What do we know about oblique incidence?

A

NOTHING

20
Q

what is transmission with a bend?

A

Refraction

21
Q

With oblique incidence and different propagation speeds what can occur?

A

Refraction

22
Q

Snells law describes what in physics?

A

Refraction

23
Q

A sound wave strikes a boundary with normal incidence, if impedances are identical, what % of sound is refracted?

A

0%

Because if impedance is the same there is no reflection

24
Q

What best describes reflection arising from a rough boundary?

A

Diffuse reflection/ Backscatter

25
Q

What processes occur when ultrasound passes through all media?

A

Attenuation ( scattering, absorption, reflection )

26
Q

What is the % of time that a system is transmitting a pulse?

A

Duty factor

*i thought this question was hard to find because it’s from chapter 4

27
Q

What is the dominant contributor to attenuation?

A

Absorption

28
Q

As path length increases attenuation…

A

Increases

29
Q

Impedance is a characteristic of …

A

The medium only

30
Q

Reflection occurs only if the 2 media have…

A

Different impedances

31
Q

As path length increase the attenuation coefficient …

A

stays the same

32
Q

IRC

A

% of intensity that bounces back when sound beam strikes boundary between two media

33
Q

ITC

A

% of intensity that passed in the forward direction when the beam strikes an interface between two media

34
Q

What is the best estimate for attenuation coefficient of sound traveling in soft tissue?

A

the attenuation coefficient is one half the frequency used in soft tissue. atten. coef.=.5 dB/cm/MHz

35
Q

2 factors for attenuation…

A

Path length

Frequency of sound

36
Q

How is attenuation affected by distance?

A

Distance and attenuation are directly related-

The farther the sound travels, the greater the attenuation (and the weaker the beam becomes)

37
Q

How is attenuation related to frequency?

A

Directly related

38
Q

What contributes to attenuation?

A

Reflection, scattering, absorption

39
Q

What term(s) describes the redirection of sound in many directions?

A

Scattering

40
Q

impedance is equal to…

A

Density (kg/m^3) • Propagation Speed (m/s)

41
Q

How is Rayleigh scattering related to frequency?

A

Proportional to frequency ^4

When frequency doubles- Rayleigh scattering is 16 times greater

DSM PHY (14 decks)

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