[AS] Waves

Question 1

What is a wave

Answer 1

A wave is the oscillation of particles or fields

Question 2

What is a progressive wave

Answer 2

A moving wave which carries energy from one place to another without transferring any material

Question 3

A wave is caused by …

Answer 3

Something making particles or fields oscillate(vibrate) at a source

Question 4

What is the displacement of a wave?

Answer 4

How far a point on the wave has moved from its undisturbed position

Question 5

What is the amplitude of a wave?

Answer 5

Maximum magnitude of displacement

Question 6

What is the frequency of a wave? What’s the equation?

Answer 6

The number of cycles that pass a given point per second

F= 1/T

Question 7

What is meant by phase difference?

Answer 7

The amount one waves lags behind another

Question 8

What is refraction?

Answer 8

The wave changes direction as it enters a different medium

Question 9

What is a transverse wave?

Answer 9

Vibrate at right angles to the direction of energy transfer

E.g. all electromagnetic waves

Question 10

What is a longitudinal wave?

Answer 10

Vibrate along the direction of energy transfer

E.g. sound

Question 11

What is polarisation?

Examples?

Answer 11

The filtering of transverse waves into just one plane of motion

Tv and radio signals

Question 12

Polarisation is evidence that …..

Answer 12

Electromagnetic waves are transverse

Question 13

What is superposition?

Answer 13

2 or more waves pass through each other

Question 14

What happens during constructive interference?

Answer 14

Crest meets crest
Or
Trough meets trough

Question 15

What happens during destructive interference?

Answer 15

Crest and trough cancel out

Question 16

How do 2 points in phase on a wave interfere?

Answer 16

Constructively

Question 17

What is meant by in phase?

Answer 17

They are both at the same point in the wave cycle

Phase difference of zero or 360 etc

Question 18

What is meant by 2 point exactly out of phase?

Answer 18

2 points with a phase difference of 180 degrees

Question 19

To get interference patterns the two sources must be coherent.
What does this mean?

Answer 19

Same wave length and frequency

Question 20

What is a stationary wave?

Answer 20

(Progressive wave reflected at a boundary)

The superposition of two progressive waves with the same frequency moving in opposite directors.

Question 21

Is energy transmitted by a stationary wave?

Answer 21

Will Mike ever dunk?😂

Question 22

How can you demonstrate a stationary wave?

Answer 22

Setting up a driving oscillator at one end of a stretched string with the other end fixed

Question 23

What is meant by resonant frequent?

Answer 23

The frequency needed to create a stationary wave

Question 24

Do stationary on strings form oscillating loops?

Answer 24

Can Marcus dunk?🤗 (yes)

Question 25

what is diffraction?

Answer 25

waves spread out as they go round cornors or through a narrow gap

Question 26

when the gap is a lot bigger than the wavelength, diffraction is......

Answer 26

unnoticeable

Question 27

when do you get the most diffraction?

Answer 27

when the gap is the same size as the wave length

Question 28

what happens if the wavelength is much bigger the the gap?

Answer 28

mostly reflection

Question 29

what do you see when demonstrating diffraction patterns with a monochromatic, coherent light source?

Answer 29

a central fringe, with dark and bright fringes alternating on either side

Question 30

what do you see when demonstrating diffraction patterns with white light?

Answer 30

multicoloured fringes

Question 31

what does light intensity mean

Answer 31

the number of photons

Question 32

describe young double slit experiment in 3 points

Answer 32

shine a laser between 2 slits slits need to be about the same size as the wavelength of the light you get a pattern of light and dark fringes depending of whether there is constructive or destructive interference

Question 33

what was youngs double slit experiment evidence for?

Answer 33

the wave nature of EM radiation

Question 34

what happens the the interference patterns of waves when you increase the number of slits? why?

Answer 34

they get sharper there are more beams reinforcing the pattern

Question 35

dsinX = n(wavelength) | what does n, X and d mean?

Answer 35

``` n = which order X = angle between zero order and n d = space between slits ```

Question 36

What is refractive index a measure of?

Answer 36

The ratio of the speed of light in two materials

Question 37

n = C/Cs | what does each letter mean?

Answer 37

``` n= refractive index C= speed of light in a vacuum Cs= speed of light in material ```

Question 38

Where do you measure the angle of incidence between?

Answer 38

The incoming ray of light and the normal

Question 39

How does the angle of refraction change when light enters an optically denser medium?

Answer 39

Refracted towards the normal

Question 40

How does the angle of refraction change when light enters an optically less dense medium?

Answer 40

Refracted away from the normal

Question 41

At what angle is light refracted along the boundary when light enters an optically less medium?

Answer 41

Critical angle

Question 42

What happens when the angle of incidence is greater than the critical angle when entering an optically DENSER medium?

Answer 42

Nothing

Question 43

What happens when the angle of incidence is greater than the critical angle when entering an optically LESS DENSE medium?

Answer 43

Total internal reflection

Question 44

What must be true about the density of the materials for total internal reflection to happen?

Answer 44

The light enters an optically less dense medium

Question 45

What is the refractive index of optical fibres?

Answer 45

HIGH

Question 46

What is the refractive index of optical fibre cladding?

Answer 46

LOW

Question 47

How does light move through a optical fibre?

Answer 47

Total internal reflection

Question 48

How can signal degradation happen in an optical fibre?

Answer 48

Absorption, Dispersion

Question 49

What is signal degradation by absorption?

Answer 49

Some of the signal's energy is lost through absorption by the material, reducing its amplitude

Question 50

What is signal degradation by dispersion?

Answer 50

Signals disperse as they travel down the wire. | Broadened pulses overlap and interfere with each-other

Question 51

What are the two types of dispersion?

Answer 51

Modal, Material

Question 52

Describe modal dispersion

Answer 52

Light enters the wire at different angles, so they take different paths.

Question 53

Describe material dispersion

Answer 53

Light of different wavelengths travels at different speeds through the wire

Question 54

How can you prevent modal dispersion?

Answer 54

Using a "single-mode fibre"

Question 55

How can you prevent material dispersion?

Answer 55

Using monochromatic light

Question 56

How can you reduce signal degradation along an optical fibre?

Answer 56

An optical fibre repeater | boosts and regenerates the signal