Unit 3 Waves

Question 1

What do waves do?

Answer 1

transfer energy from 1 place to another by oscillating, and we can interpret that energy into meaningful information. however they cannot transfer matter.

Question 2

What is a distance/displacement graph?

Answer 2

a graph that shows how far the wave has travelled from the starting point compared to how far from the equilibrium the wave has oscillated

Question 3

What is amplitude?

Answer 3

the maximum displacement

Question 4

What is wavelength?

Answer 4

the distance of one entire oscillation

Question 5

What are some ways to measure wavelenth?

Answer 5

crest to crest, trough to trough, equilibrium to equilibrium

Question 6

What is a displacement/time graph?

Answer 6

a graph that shows how far from the equilibrium point the wave has oscillated in a certain amount of time

Answer 7

the wavelength is the time period of one full oscillation

Question 8

What is frequency?

Answer 8

number of complete oscillations per second

Question 9

What is the unit for frequency?

Answer 9

Hz, hertz

Question 10

What is the formula for frequency?

Answer 10

frequency (hz) = 1/time (s)

Question 11

What is the wavespeed?

Answer 11

total distance travelled by the wave in a given amount of time

Question 12

What is the formula for wavespeed?

Answer 12

wavespeed (m/s) = frequency (Hz) x wavelength (m)

Question 13

What are transverse waves?

Answer 13

waves that oscillate perpendicular to the direction of energy transfer

most waves are transverse

Question 14

What direction to transverse waves follow?

Answer 14

travel left to right, up and down oscillations

Question 15

What are some examples of transverse waves?

Answer 15

electromagnetic waves, light waves, radio waves, ripples

Question 16

What are longitudinal waves?

Answer 16

waves that oscillated parallel to the direction of energy transfer

some regions are more spread out and some are compressed because the waves vibrate back and forth and different speeds

Question 17

What are some examples of longitudinal waves?

Answer 17

sound waves, seismic p waves

Question 18

What are electromagnetic waves?

Answer 18

transverse waves that transfer energy from the source of the waves to the absorber

Question 19

What speed are electromagnetic waves at in a vaccum?

Answer 19

the all travel at the same speed (3x10^8)

Question 20

Describe the motion of electromagnetic waves through different mediums

Answer 20

when they go through different mediums they travel at different speeds which leads to refraction. the wavelengths and frequencies differentiate the waves

Question 21

What is the relation between wavelength and frequency?

Answer 21

inversely related

Question 22

What happens when an electromagnetic comes into contact with something?

Answer 22

reflected, absorbed or transmitted (or a combination of all)

Question 23

What are sound waves?

Answer 23

longitudinal waves that can be reflected, refracted and absorbed. they are vibrations that pass through the molecules of a medium and cause collisions that transmit the sound to the other side. the frequency will never change but speeds can.

Question 24

What happens when a wave comes into contact with a boundary?

Answer 24

a boundary is a surface
it can be absorbed, transmitted (refraction), and reflected
depends based on wavelength and properties of two materials

Question 25

What is the main rule for ray diagrams?

Answer 25

angle of incidence = angle of reflection

Question 26

What is the normal?

Answer 26

in a ray diagram the normal is a line that is perpendicular to the boundary

Question 27

What are the types of reflection?

Answer 27

specular reflection, diffuse/scattered reflection

Question 28

What is specular reflection?

Answer 28

when the boundary is flat so the all incoming light rays will be reflected in the same direction. it gives a clear image.

Question 29

What is diffuse/scattered reflection?

Answer 29

when the boundary is bumpy so the normal is all in different directions making the light reflect in different directions.

Question 30

What is refraction?

Answer 30

when waves change direction as they pass from one medium to another

Question 31

Why do waves travel at different speeds in different mediums?

Answer 31

because they have different densities. high density makes a slower wave and vice versa

Question 32

When will a wave be refracted?

Answer 32

when it hits the boundary at an angle it will be reflected and it's direction will change. if it hit it perpendicular it will move straight.

Question 33

Which way towards the normal will the wave move depending on the density of the medium they're passing through?

Answer 33

if its passing into a more dense medium it will bend towards normal if its passing into a less dense medium it will bend away from normal

Question 34

Does the frequency ever change?

Answer 34

no it remains constant

Question 35

What is the relationship between wavespeed and wavelength?

Answer 35

directly proportional

Question 36

Does wavelength vary refraction amount?

Answer 36

yes, different wavelengths are refracted by different amounts

Question 37

What happens in the white light triangular experiment?

Answer 37

when white light enters a triangular prism all the colours will bend to different degrees and spread out

Question 38

What is the refractive index?

Answer 38

a measure of the speed of light as it passes through that material compared to the speed of light as it passes through a vacuum

Question 39

How does the refractive index of a material affect the wavespeed?

Answer 39

light travels through materials with a higher refractive index slower light travels through materials with lower refractive index faster

Question 40

What is a vaccum?

Answer 40

the medium with the lowest refractive index (refractive=1) light travels faster in this medium

Question 41

How to find refractive index of a material?

Answer 41

speed of light in vaccum/speed of light in material n=c/v

Question 42

What is Snell's Law?

Answer 42

n = sin i/sin r i = angle of incidence r = angle of refraction n = refractive index

Question 43

What is total internal reflection?

Answer 43

if angle of incidence is greater than critical angle no refraction occurs and all light is reflected back into denser medium

Question 44

What happens when light travels from a more dense to less dense medium?

Answer 44

it speeds up and is refracted away from normal

Question 45

What is the criteria for total internal reflection?

Answer 45

the rays of light must travel from more dense to less dense medium and angle of incidence must be greater than the critical angle

Question 46

What happens when the angle of incidence is less than the critical angle?

Answer 46

light ray refracted away from normal

Question 47

What happens when the angle of incidence is equal to the critical angle?

Answer 47

the light ray is refracted 90° to the normal and the ray travels along the surface of the denser medium

Question 48

What is the equation for the critical angle?

Answer 48

sin(c) = 1/n c = critical angle n = refractive index

Question 49

What does the exact value of the critical angle depend on?

Answer 49

the refractive index of that specific material