Physics 1 Test Ch 6, 7

Question 1

How is intensity calculated?

Answer 1

Power/area

Question 2

What are the units for intensity?

Answer 2

W/cm^2

Question 3

What are the names for normal incidence?

Answer 3

Perpendicular
Orthogonal
Right angle
Normal
Ninety degrees

Question 4

Any angle other than 90 degrees

Answer 4

Oblique

Question 5

An acute angle is..

Answer 5

Less than 90 degrees

Question 6

An obtuse angle is..

Answer 6

Greater than 90 degrees

Question 7

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

Answer 7

Incident intensity

Question 8

the portion of incident intensity and reflected completly

Answer 8

Reflected intensity

Question 9

normal incidence is what degree?

Answer 9

90 degrees

Question 10

portion of incident intensity after striking boundary that continues?

Answer 10

Transmitted intensity

Question 11

% of ultrasound intensity when sound strikes a boundary?

Answer 11

Intensity Reflection Coefficient (IRC)

Question 12

% of ultrasound that is allowed to pass through?

Answer 12

Intensity Transmission Coefficient (ITC)

Question 13

Intensity reflection coefficient and intensity transmission coefficient have what units?

Answer 13

No units

They are percentages

Question 14

with normal incidence,reflection depends upon different what?

Answer 14

Different impedance

Question 15

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

Answer 15

Substantially different

Question 16

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

Answer 16

I found this information online I think…

reflection increases

Question 17

specular reflections arise when the interface is…

Answer 17

Smooth

Question 18

The 2 physical principles always apply to oblique incidence

Answer 18

1) Conservation of energy

2) Reflection angle=incident angle

Question 19

What do we know about oblique incidence?

Answer 19

NOTHING

Question 20

what is transmission with a bend?

Answer 20

Refraction

Question 21

With oblique incidence and different propagation speeds what can occur?

Answer 21

Refraction

Question 22

Snells law describes what in physics?

Answer 22

Refraction

Question 23

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

Answer 23

0%

Because if impedance is the same there is no reflection

Question 24

What best describes reflection arising from a rough boundary?

Answer 24

Diffuse reflection/ Backscatter

Question 25

What processes occur when ultrasound passes through all media?

Answer 25

Attenuation ( scattering, absorption, reflection )

Question 26

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

Answer 26

Duty factor *i thought this question was hard to find because it's from chapter 4

Question 27

What is the dominant contributor to attenuation?

Answer 27

Absorption

Question 28

As path length increases attenuation...

Answer 28

Increases

Question 29

Impedance is a characteristic of ...

Answer 29

The medium only

Question 30

Reflection occurs only if the 2 media have...

Answer 30

Different impedances

Question 31

As path length increase the attenuation coefficient ...

Answer 31

stays the same

Question 32

IRC

Answer 32

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

Question 33

ITC

Answer 33

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

Question 34

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

Answer 34

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

Question 35

2 factors for attenuation...

Answer 35

Path length | Frequency of sound

Question 36

How is attenuation affected by distance?

Answer 36

Distance and attenuation are directly related- | The farther the sound travels, the greater the attenuation (and the weaker the beam becomes)

Question 37

How is attenuation related to frequency?

Answer 37

Directly related

Question 38

What contributes to attenuation?

Answer 38

Reflection, scattering, absorption

Question 39

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

Answer 39

Scattering

Question 40

impedance is equal to...

Answer 40

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

Question 41

How is Rayleigh scattering related to frequency?

Answer 41

Proportional to frequency ^4 | When frequency doubles- Rayleigh scattering is 16 times greater