Reflections and Rarefactions

Question 1

reflection

Answer 1

the wave bounces off the new medium

Question 2

transmission

Answer 2

the wave starts moving through the new medium

Question 3

absorption

Answer 3

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

Question 4

what are wave fronts

Answer 4

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

Question 5

what are rays

Answer 5

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

Question 6

what is the reflected ray

Answer 6

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

Question 7

what is the incident ray

Answer 7

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

Question 8

what is the angle of incidence

Answer 8

angle between normal and incident ray

Question 9

what is the angle of reflection

Answer 9

is the angle between the reflected ray and the normal

Question 10

law of reflection

Answer 10

angle of incidence = angle of reflection

Question 11

what is reverberation

Answer 11

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

Question 12

what is an echo

Answer 12

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.

Question 13

what does the speed of the sound waves depend on

Answer 13

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.

Question 14

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

Answer 14

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

Question 15

why do wavefronts refract

Answer 15

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.

Question 16

refraction of sound waves entering a denser or hotter medium

Answer 16

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

Question 17

refraction of sounds waves entering a less dense and cooler medium

Answer 17

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

Question 18

what is the critical angle

Answer 18

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

Question 19

what is total internal reflection

Answer 19

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.

Question 20

how is refraction of sound used in real life

Answer 20

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

Question 21

snells law

Answer 21

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

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