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Physics II > test 1 > Flashcards

test 1 Flashcards

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1
Q

What are the two types of waves?

A
  1. Mechanical (physical medium)
  2. Electromagnetic (vaccum)
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2
Q

What is a transverse wave?

A

Particle motionis transverse to wave direction.

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3
Q

What is a longitudinal wave?

A

The direction of the wave is parallel to the direction.

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4
Q

What does “trans” mean?

A

Across

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5
Q

What does “ducere” mean?

A

To lead.

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6
Q

What does a transducer do?

A

It converts one form of energy to another.

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7
Q

What are some examples of “transducers” (Ea→Eb)

A
  • Microphone
  • Spekers
  • Light Bulbs
  • Eyes
  • Ears
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8
Q

T/F:

Is an ultrasound transducer bidirectional.

A

True.

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9
Q

What is the peizoelectric effect?

A

It converts voltage energy into pressure.

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10
Q

What does “piezo” mean?

A

Pressure.

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11
Q

What does “electrum” mean/consist of?

A

Amber, which is Au/Ag conductive mixture.

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12
Q

What are some materials that are peizoelectric?

A
  • Quartz
  • PZT
    • Pb=Lead
    • Zinconate
    • Titanate
  • Ceramics
  • Ceramic admixtures
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13
Q

What is polarization?

A

It is the separation of (+) and (-) changes.

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14
Q

What are the 5 steps to polarization?

A
  1. Apply heat
  2. Apply magnetic field
  3. Remove heat
  4. Remove magnetic field
  5. Crystalline sets.
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15
Q

How do you find the curie temperature?

A

(300xCx9/5)

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16
Q

What is the impedance of a transducer?

A

30 MR

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17
Q

What are the components of a transducer from top to bottom (chord)?

A
  1. 1/2 λ matching layer
  2. PZT
  3. Backing material
  4. Tuning coil
  5. Coaxial cable
  6. Metal shield
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18
Q
A
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19
Q
A
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20
Q
A
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21
Q

What does the backing material do?

A

It shortens the ring of the transducer.

(muffles sound tone and duration)

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22
Q

What is used to avoid reflection at the PZT?

A

Backing material interface.

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23
Q

Why is the backing material used to avoid relfection at the PZT: backing material interface?

A

Because it has a similar impedance as PZT.

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24
Q

What is the unit for impedance?

A

Rayls= kg/m2xsec

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25
Q

What is the formula for impedance?

A

Z=density x speed

Z=p x c

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26
Q

What is the unit for density?

A

kg/m3

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27
Q

What is the unit for speed?

A

m/sec

28
Q

What is the formula for % reflected?

A

100-% transmission

or

[(Z2-Z1)/(Z2+Z1)]2X100

29
Q

What does the “¼ λ matching layer” do?

A

It elminates reflecting waves by constructive and destructive interference.

30
Q

Waves offset by ½ λ results in what?

A

Total destructive interference.

¼ λ (out to surface)+¼ λ(back from surface)=½ λ

31
Q

What is the impedance of soft tissue?

A

1.7MR

32
Q

What is the equation for ¼ λ matching layer?

A

ZML=√ZPZTxZST

33
Q

What does a big difference in impedances lead to?

A

Reflection.

34
Q

What is destructive interference?

A

When 2 waves come together and cancel eachotherout.

35
Q

What does into creating a sound wave?

A
  • Start with a piezoelectric transducer
  • Apply alternating electric voltage across PZT
  • Expand and contract PZT
  • Exerts pressure wave (sound) from PZT surface
  • Transmitted into tissues→reflected from tissue
  • Reflected pressure wave deforms PZT→Voltage
36
Q

What is the lateral resolution affected by?

A

Beam width.

37
Q

What are the 3 parts of the beam width?

A

Converge→Focus→Diverge

38
Q

What does a smaller BW signify?

A

Better lateral resolution

39
Q

What are the effects of the transducer frequency on beam?

A
  • The higher the frequency, the smaller divergence in the far field.

BUT…THE HIGHER THE FREQUENCY, THE GREATER THE ATTENUATION.

40
Q

What is the near field also known as?

A

Near zone length or fresnel zone.

41
Q

What is the end of the near zone length known as?

A

Focus

42
Q

What is the equation for the NZL?

A

NZL=D2/4 λ

43
Q

What is the equation for λ?

A

λ=c/f

44
Q

What is the farfield also known as?

A

Fraunhoffer Zone

45
Q

What is the equation for the Fraunhoffer Zone?

A

SINØ=1.2c/Df

46
Q

What happens to frequency if SINØ increases?

A

Frequency decreases.

47
Q

What are the 3 resolution planes?

A
  1. Lateral resolution
  2. Axial resolution
  3. Elevation resolution
48
Q

What is resolution?

A

It os the bility to see two objects as seperate.

49
Q

What is lateral resolution?

A

It is the ability to distinguish 2 structures that are perpendicular to the direction of the beam.

50
Q

What does lateral resolution consist of?

A

L-A-T-A

LATERAL

ANGULAR

TRANSVERSE

AZIMUTHAL

51
Q

What is lateral resolution associated with?

A

Beam width.

52
Q

What does determines beam width?

A

It varies with depth.

53
Q

Where can you find the best lateral resolution?

A

At the focus (narrowest=D/2)

54
Q

What does axial resolution consist of?

A

L-A-R-R-D

  • Longitudinal
  • Axial
  • Range/radial
  • Depth
55
Q

Describe axial resolution:

A

Pulse duration

56
Q
A
57
Q

In axial resolution, what creates a better resolution?

A

Shorter pulse durations.

58
Q

What is the formula for axial resolution

A

PD=Nc*T

T=1/f

59
Q

If the pulse duration goes up, what happens to the brandwidth?

A

BDW goes down

60
Q

The bigger the BDW, the _____ the quality.

A

Worst.

61
Q

Which plane is known as the “forgotten” plane?

A

Elevation plane.

62
Q

Elevation resolution is similar to what?

A

Lateral resolution.

63
Q

Where is the best resolution seen in an elevation plane?

A

At the focus.

64
Q

What is a huygen?

A

It is a basic assembly.

  • It is a row of single element transducers
  • Individual electrical signals to each transducer
  • Grouped together to form an image.
65
Q

What is huygen’s principle?

A

It has phase delays to transducer and it allows for beam steering and focusing.

Physics II (4 decks)

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