Lesson 8 (Part 1) Flashcards Preview

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Flashcards in Lesson 8 (Part 1) Deck (30)
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1

What is the opposite of reflection?

Transmission

2

Reflection

The throwing back by a body or surface of light, heat or sound without absorbing it

3

What happens at each point boundary with perpendicular incidence? (2)

1. Some of the sound is reflected
2. Some of the sound beam goes through

4

What is another word for perpendicular incidence?

90 degree incidence

5

IRC

Intensity reflection coefficient

6

Intensity reflection coefficient

Is the ratio of the intensity of the reflected wave relative to the incident (transmitted) wave

7

Incident pulse

Is a pulse where the incident moves towards (i.e., approaching) the boundary with the pole

8

Reflected pulse

A pulse with an upward displacement will reflect off the end and return with a downward displacement
- an echo

9

Transmitted pulse

The amplitude is representative of the energy carried by a wave

10

What is the equation for IRC?

IRC = echo intensity/incident sound intensity x 100%

11

ITC

Intensity transmission coefficient

12

Intensity transmission coefficient

Is a measure of how much of an electromagnetic wave (light) passes through a surface or an optical element
- can be measured for amplitude or intensity

13

What is the formula for ITC?

ITC = transmitted intensity/ incident sound intensity x 100%

14

What is the relationship between impedance and density / propagation speed?

Directly proportional

15

Where is impedance the highest?

In solid structures
- eg. bone

16

Where is impedance the lowest?

In air

17

What does impedance depend on?

Densities

18

What does it mean when you have a higher difference in impedance?

A brighter echo

19

What does IRC + ITC equal?

100%

20

What is the % of transmitted pulses?

80%

21

What is the % of reflected pulses?

20%

22

How much goes through and how much is reflected depends on what?

Impedance

23

What is the formula for impedance?

z = p x c
z = impedance
p = density
c = propagation speed

24

What is the unit for impedance?

Rayls
- kg x m / m^3 x s

25

Does each tissue have its own impedance?

Yes

26

What is the formula for acoustic impedance mismatch?

delta z = z2 - z1

27

What does the amount of reflection depend on?

delta z

28

What is the formula for IRC? (involving impedance)

IRC = (z2-z1 / z2+z1)^2

29

What does delta z decide?

If the echo will appear bright or dark

30

What does increase in delta z mean?

Brighter echo