# Reflections and Rarefactions Flashcards

1
Q

reflection

A

the wave bounces off the new medium

2
Q

transmission

A

the wave starts moving through the new medium

3
Q

absorption

A

the wave’s energy is absorbed by the new medium as heat

4
Q

what are wave fronts

A

lines that correspond to the crests of the wave
waves are represented using wavefronts

5
Q

what are rays

A

they represent waves in the form of arrows.
the are drawn perpendicular to the wavefronts in the direction the wave is moving.

6
Q

what is the reflected ray

A

represents the wave after it is reflected by the surface. leaves the surface from the same point

7
Q

what is the incident ray

A

represent the wave that approaches the surface.
meets the surface at the base of the normal

8
Q

what is the angle of incidence

A

angle between normal and incident ray

9
Q

what is the angle of reflection

A

is the angle between the reflected ray and the normal

10
Q

law of reflection

A

angle of incidence = angle of reflection

11
Q

what is reverberation

A

when this time interval is shorter than 0.1 seconds, your brain interprets the waves as a single sound.

excessive reverberation make it hard to comprehend

12
Q

what is an echo

A

when a reflected wave reaches your ears more than 0.1 seconds after you hear the original, you can hear the reflected sound as an echo.

13
Q

what does the speed of the sound waves depend on

A

if there is a smaller distance between the particles in the medium sound waves travel faster

at higher temperatures, particles move faster and can transfer energy quicker.

14
Q

what happens when a wave moves from one medium to another and its velocity changes

A
• its frequency remains constant
• wavelength changes
• if the wave enters the new medium at an angle, it refracts
15
Q

why do wavefronts refract

A

the part of the wavefront that reaches the boundary first slows down or speeds up, while the remainder of the wavefront still in the original medium continues at original speed.

16
Q

refraction of sound waves entering a denser or hotter medium

A

velocity and wavelength increase and the wave bends away from the normal (angle of refraction is bigger than angle of incidence)

17
Q

refraction of sounds waves entering a less dense and cooler medium

A

velocity and wavelength decreases
- wave bends towards the normal (angle of incidence is greater than angle of refraction)

18
Q

what is the critical angle

A

eventually the angle of refraction reaches 90 degrees from the noral and the wave travels along the boundary between the two mediums. this is the angle of incidence is called the critical angle

19
Q

what is total internal reflection

A

when angle of incidence is bigger than critical angle, refraction doesnt occur anymore and the wave is entirely reflected and does not enter the other medium.

20
Q

how is refraction of sound used in real life

A

sound waves reflect back and forth along the inner walls of a tube in a stethoscope and carries sound

total internal reflection protects marine life from most sound produced by wind turbines

21
Q

snells law

A

sin (angle of reflection)/sin (angle of incidence)

velocity of reflection/velocity of incidence
=
wavelength of reflection/wavelength of incidence