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Flashcards in Lesson 6 Deck (24)
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1

What allows attenuation to occur? (3)

1. Absorption
2. Reflecting
3. Scattering

2

What is absorption?

The transfer of sound to heat

3

What makes up an image? (2)

1. Reflecting
2. Scattering

4

What does 0dB mean?

You cant hear anything

5

What happens as decibels get higher?

It gets louder

6

What does 3dB mean?

2x

7

What does 10dB mean?

10x

8

What is the unit for attenuation?

Decibels
- dB

9

What do decibels describe?

The relationship between various measured sound levels

10

What is the formula for attenuation?

a = ac x L
a = attenuation
ac = attenuation coefficient
L = length traveled

11

Attenuation coefficient

Attenuation that occurs with each cm the sound travels

12

What is the unit for attenuation coefficient?

dB/cm

13

What is attenuation depend on? (3)

1. Type of tissue
2. Length/distance of travel
3. Frequency

14

What does it mean when your image is more fuzzy?

Less sound is traveling through

15

How much sound goes through bone?

None

16

What structures have high attenuation? (4)

1. Bone
2. Stomach
3. Lungs
4. Fatty liver

17

What structures have low attenuation? (2)

1. Normal liver
2. Bladder

18

What is ac in soft tissues?

Half of the frequency
- 0.5 x freq. x length

19

What happens to attenuation if frequency increases?

It increases

20

What happens to attenuation if distance increases?

It increases

21

What are 5 forms of energy?

1. Heat
2. Light
3. X-rays
4. Microwaves
5. Mechanical motion

22

What happens to attenuation if the coefficient increases?

It increases

23

What happens to penetration if frequency increases?

It decreases

24

Attenuation

Weakening of sound