Lesson 12

Question 1

What kind of wave is sound?

Answer 1

Mechanical

• not ionizing radiation
• not electromagnetic

Question 2

What movement can sound do? (2)

Answer 2

1. Converge

2. Diverge

Question 3

What are 2 other names for transducer assembly?

Answer 3

1. Probe

2. Scan head

Question 4

What is the order of transducer assembly? (4)

Answer 4

1. Case
2. Damping material
3. Element
4. Matching layer

Question 5

Transduce

Answer 5

Convert one form of energy into another

Question 6

What happens if you change the shape of the transducer?

Answer 6

It creates sound through pressure

- happens so fast it creates ultrasound

Question 7

AV

Answer 7

Alternating voltage

Question 8

What does alternating voltage allow?

Answer 8

The thickness and thinness of an element to change

- creates a mechanical wave

Question 9

When is AV used?

Answer 9

In doppler

Question 10

What is the break down of piezoelectricity? (2)

Answer 10

1. Piezo
   - press
2. Elektron
   - amber

Question 11

What is being converted in piezoelectric effect?

Answer 11

Pulse of sound to voltage (echo)

Question 12

What is being converted in reverse piezoelectric effect?

Answer 12

Voltage (echo) to a pulse for sound

Question 13

What is a piezoelectric element also known as?

Answer 13

A crystal

Question 14

What is 1 cycle of alternating voltage equivalent to?

Answer 14

2/3 cycles of a pulse

Question 15

What does a longer alternating voltage mean?

Answer 15

A longer pulse

- doppler

Question 16

What does returning echoes that affect the element create?

Answer 16

Voltage

Question 17

Quartz

Answer 17

One of the first natural piezoelectric crystals

Question 18

What are synthetic crystals made from? (4)

Answer 18

1. Lead
2. Zirconate
3. Titanate
4. Barium

Question 19

What are piezo-electric elements usually made of?

Answer 19

Lead zirconate titanate

- PZT

Question 20

How is PZT created?

Answer 20

It is placed in a strong magnetic field at a hight temp and it realigns its molecular dipoles and then cooled

Question 21

What would happen if you brought the crystal back to the curie point but without the magnetic field?

Answer 21

It loses its electric properties and the dipoles will scatter
- not electric anymore

Question 22

What happens during polarization of the piezo-electric elements?

Answer 22

The dipoles align

Question 23

Curie point

Answer 23

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

Question 24

What is the curie point of PZT?

Answer 24

350 deg C

Question 25

When might you lose the electric properties of the probe?

Answer 25

If you put it in sterilizing solution

Question 26

What do piezo-electric elements have?

Answer 26

Natural vibrational frequency

Question 27

What does operating frequency depend on? (2)

Answer 27

1. Propagation speed of the element

2. Thickness of the element

Question 28

What kind of noise does a little bell make? (2)

Answer 28

1. Higher pitch

2. Higher frequency

Question 29

What kind of noise does a big bell make? (2)

Answer 29

1. Lower pitch

2. Lower frequency

Question 30

What can we use to adjust the transducer frequency?

Answer 30

Voltage frequency

Question 31

What are we dealing with when we are using a pulsed wave?

Answer 31

Bandwidth

Question 32

Multi-Hertz operation

Answer 32

2 or 3 frequencies on the same element

Question 33

What does PRF of voltage also affect?

Answer 33

PRF of pulse

Question 34

What is the relationship between PRF and depth?

Answer 34

Inversely proportionate

Question 35

What happens to depth when PRF increases?

Answer 35

It decreases

Question 36

Range ambiguity

Answer 36

Is a technique used with medium PRF radar to obtain range information for distances that exceed the distance between transmit pulses
- needed for doppler