Waves and Sounds lll

Question 1

What are the different behaviors that may occur with incident waves depending on the context? (5) ex; By interacting with a boundary, a sound may be ___________

Answer 1

Transmitted
Refracted
Reflected
Diffracted
Phase shifted

Question 2

True or False: there may be a loss of energy during the transition of a waves against a boundary?

Answer 2

True

Question 3

Which of these pairs are out of phase?

Answer 3

2 and 3

Question 4

Which are these pairs are TOTALLY out of phase?

Answer 4

3

Question 5

Waves are out of phase when there is a difference of a ____________ cycle.

Answer 5

a full half cycle
(180 degrees or pi radians)

Question 6

What is reflection?

Answer 6

The bouncing back of a wave as it encounters boundary.

Question 7

What is Refraction?

Answer 7

• The bending/redirection of the path of a wave as it encounters a boundary.
• It is a transmission process THROUGH a boundary

Question 8

What is Diffraction?

Answer 8

The redirection of the path of a wave AROUND a boundary that is opaque to the wave
- No Transmission through the boundary

Question 9

What is the relation between a fixed boundary and the reflection of a wave? (3)

Answer 9

The wave will

Question 10

What is the relation between a fixed boundary and the reflection of a wave?

Answer 10

• Reflected and Inverted
• Newton’s third law
• Phase shift
  (When the pulse reaches the fixed end, it stretches the string more than normally, which causes a larger elastic pull than normal, so the pulse will be reflected upside-down back to the right)

Question 11

What is the relation between a moveable boundary and the reflection of a wave? (2)

Answer 11

• Reflected and upright
• No phase shift
  (When the pulse reaches the lose end, it simply flops upward, so the pulse is reflected right-side-up back to the right)

Question 12

What is thin-to-Thick transition?

Answer 12

Low density to high density material boundary

Question 13

What is Thick-to-thin transition?

Answer 13

high density to low density material boundary

Question 14

What happens to the wave in thin-to-Thick transition? (2)

Answer 14

• Some reflection and inversion (some phase shift)
  -Some transmission

Question 15

What happens to the wave in Thick-to-Thin transition? (2)

Answer 15

• Some reflection
• Some transmission
  No phase shift

Question 16

What is impedance?

Answer 16

Physical characteristic quantifying how much a wave is absorbed/reflected vs. how much is transmitted through the material

Question 17

What occurs if there is absence of measurable impedance? (2)

Answer 17

• Waves will travel indefinitely
• Will not lose or dissipate energy

Question 18

What are the two primary parts of impedance?

Answer 18

Reactance (X)
Resistance (R)

Question 19

What is reactance ?

Answer 19

Energy stored, inertia force

Question 20

What is resistance?

Answer 20

Energy dissipated

Question 21

Impedance depends on 3 characteristics, what are they?

Answer 21

Elasticity
Density
Internal friction

Question 22

When there is an impedance mismatch between two materials, it affects how much of an incident wave is ____________ compared to how much is _____________ or ____________.

Answer 22

transmitted
Reflected or absorbed

Question 23

What is the formula of impedance mismatch ratio?

Answer 23

Question 24

What would occur in the extreme case where two materials have very comparable (almost equal) impedance? (2)

Answer 24

• About 100% of the energy will be transmitted
  (very little loss of wave’s intensity)
• Anechoic system/material

Question 25

What would occur in the extreme where the second material has a much more greater impedance than the first material? (3)

Answer 25

• 0 transmission
• Echo
• Reverberant surface

Question 26

What occurs in constructive interference?

Answer 26

Reinforcement effect

Question 27

What occurs in destructive interference?

Answer 27

Cancellation effect