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Physics > Lecture 12 > Flashcards

Lecture 12 Flashcards

1
Q

Sound can ____/______

A

Converge/diverge

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2
Q

Sound is _______ and is not ______ 0r _______

A

A mechanical wave

Is not ionizing radiation

Is not electromagnetic

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3
Q

Transducer assembly aka _____ or______

A

Probe

Scan head

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4
Q

Probe made of (4)

A

Element, damping material, matching layers, and case

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5
Q

What does transduce mean

A

Convert one form of energy into another

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6
Q

Converse piezoelectric effect

A

Turning pulse/echo into voltage

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7
Q

Reverse piezoelectric effect

A

Turning voltage into pulse/echo

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8
Q

Piezo-electric element aka

A

Crystale

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9
Q

Adding a voltage causes thickness of ____ to change. This creates a ____

A

Element

Mechanical wave

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10
Q

1 cycle of alternating voltage —>

A

2/3 cycles of pulse

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11
Q

Longer alternating voltage ==

A

Longer pulse (doppler )

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12
Q

Returning echo affects the _____ and this creates a ______

A

Element

Voltage

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13
Q

What is one of the first natural piezoelectric crystals

A

Quartz

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14
Q

We now make synthetic crystals with which types of ceramics

A

Lead
Zirconate
Titanate
Barium

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15
Q

Electric elements are usually made of _____

A

Lead zirconate titanate

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16
Q

Lead zirconate titanate is aka

17
Q

We make PZT piezo electric my

A

Placing it in a strong magnetic feild at a high temp (350) which realigns its molecular dipoles

18
Q

When piezo electric elements are heated, what happens

A

The molecules spread out

19
Q

When piezo electric elements are polarized, what happens

A

The dipoles align

20
Q

piezo electric elements are cooled while in

A

Magnetic field

21
Q

What is the curie point

A

The temp in which the magnetic properties of a solid can be changed

22
Q

The curies point of PZT is

A

350 degrees

23
Q

piezo electric element has a ________ frequency

A

Natural vibrational frequency

24
Q

The natural frequency of piezo electric element can also be called (3)

A

Fundamental freq
Operational freq
Resonance freq

25
Q

Operating frequency depends on ____

26
Q

Propogation speed of PZT element

27
Q

Thickness of element

A

Th

0.2-1 mm

28
Q

2 x th = ______

A

Wavelength

29
Q

To get different frequencies we would have to

A

Change crystals/transducers

30
Q

In present day systems, they are bit more complex and can uses the _________ to adjust the transducer frequency

A

Voltage frequency

31
Q

With pulsed wave we are dealing wiht a ______

32
Q

2 or 3 freq on the same element =

A

Multihertz operation

33
Q

PRF of voltage also affects PRF of

34
Q

Piezo-electric element is inversely proportional to

35
Q

If you need to go farther down you must _______ PRF

36
Q

If PRF is not decrease when trying to go deeper you get

A

Range ambiguity / echo misplacement

37
Q

For 2d ultrasound ______ automatically accomodates

Physics (32 decks)

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