Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

a-level physics > Waves and optics > Flashcards

Waves and optics Flashcards

1
Q

what is a progressive wave

A

a wave that transfers energy from one point to another without transferring the medium itself

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are mechanical waves

A

types of waves transmitted through a material by particle vibration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are electromagnetic waves

A

waves transmitted by the oscillations of electric and magnetic fields

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the frequency of a wave

A

the number of complete oscillations per unit time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what happens to the wavelength of a wave when frequency decreases

A

the wavelength increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what happen tit the wavelength of a wave when frequency increases

A

wavelength decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is phase difference

A

a measure of how much a point on a wave is in front or behind another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what does it mean when waves are in phase

A

both their crests and troughs are aligned

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what does it mean when a wave is in anti-phase

A

when the crest of one wave aligns with the trough of another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what are transverse waves

A

waves which oscillate perpendicular to the direction of energy transfer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are longitudinal waves

A

waves which oscillate parallel to the direction of energy transfer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

examples of transverse waves

A

-all electromagnetic waves
-vibrations on a guitar string

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are the electromagnetic waves

A

radio waves
microwaves
infrared
visible light
ultraviolet
x-rays
gamma rays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

can transverse waves be polarised

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

examples of longitudinal waves

A

sound waves
ultrasound waves
waves through a slinky coil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

can longitudinal waves be polarised

A

no

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is polarisation

A

when particle oscillations occur only in one of the directions perpendicular to the direction of wave propagation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

why does polarisation only occur in transverse waves

A

because transverse waves oscillate in any plane perpendicular to the propagation direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

when will two waves superpose to form a stationary wave

A

when 2 progressive waves meet eachother on a string/object with finite distance, and are traveling in opposite directions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is the principle of superposition

A

when two or more waves with the same frequency arrive at a point, the resultant displacement is the sum of the displacements of each wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is a stationary wave

A

a wave of a fixed pattern of vibrations and no energy is transferred

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what are nodes and antinodes

A

nodes- regions where there is no vibration
antinodes- regions where the vibrations are at their maximum amplitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is constructive interference

A

when the peaks and troughs line up on both waves and the resultant wave has double the amplitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is destructive interference

A

the peaks on one wave line up with the troughs of the other. the resultant wave has no amplitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what are resonant frequencies
specific frequencies where a whole number of half wavelengths will fit on the length of the string
26
how can you demonstrate sound waves are stationary waves
by placing a fine powder inside an air column and a load speaker at the open end. at certain frequencies the powder forms evenly spaced heaps along the tube, showing where there is zero disturbance as a result of the nodes of the stationary wave
27
what are harmonics
different patterns of stationary waves which depend on the frequency of the vibration and the situation in which they are created
28
what happens to harmonics when frequency is increased
more harmonics appear
29
what is the wavelength and frequency of the first harmonic
λ= 2L f= V/2L
30
what is the wavelength and frequency of the second harmonic
λ= L f= V//
31
what is the wavelength and frequency of the third harmonic
λ= 2L/3 f= 3V/2L
32
what is the frequency for the nth harmonic
nth Frequency= n x frequency of first harmonic
33
what is refraction
the change in direction of a wave when it passes through a boundary between mediums of different density
34
what causes the change of direction of a wave when it passes a boundary between two mediums
a change in speed of different parts of the wavefront as they hit the boundary
35
what happens to a wave when a medium is more optically dense
the wave travels slower and the angle of refraction is smaller. light bends towards the normal
36
what happens when a wave enters a more optically dense medium
the wave travels faster and angle of refraction is larger. light bends away from the normal
37
what determines the amount of refraction that takes place
the difference between the angles of incidence and refraction of the waves at the boundary
38
what happens when a light ray is incident on the boundary at 90 degrees
the wave passes straight through without direction because the whole wavefront enters the boundary at the same time
39
what is refractive index
a measure of how easy it is for light to travel through a material. it tells us how optically dense it is
40
what is the refractive index of a medium more optically dense than air
n > 1
41
what is the refractive index of a medium less optically dense than air
n<1
42
how do you calculate refractive index
n = c / cs
43
how to calculate the relative refractive index between two mediums which are not air
1n2 = c1/ c2 = n2/n1 = sin θ1/ sin θ2
44
what is snells law
it relates the angle of incidence to the angle of refraction at a boundary between two media and is given by n1 sin θ1= n2 sin θ2
45
what is total internal reflection
a special case of refraction that occurs when the angle of incidence within a denser medium is greater than the critical angle ( n1>n2)
46
what is the law of reflection
angle of incidence = angle of reflection
47
what type of medium has a higher refractive index
a denser medium
48
what happens to the angle of refraction as the angle of incidence is increased
it increases
49
what happens to a light ray when angle of incidence < critical angle
the light ray is refracted and exits the material
50
what happens to a light ray when angle of incidence = critical angle
-angle of refraction would be 90 degrees -the refracted ray is refracted along the boundary between the two materials
51
what happens to a light ray when angle of incidence > critical angle
-refraction does not occur -the ray undergoes total internal reflection
52
what is the formula for the critical angle
Sinθc = N2/ N1 = Sinθ1/ Sinθ2
53
what is an optical fibre
a thin piece of flexible glass surrounded by a layer of cladding
54
what is monochromatic light
light which consists of one wavelength
55
how does fibre optics work/ how does light reflect along optical fibres
-light, normally monochromatic, refracts when it enters the optical fibre at one end -it undergoes repeated total internal reflection against the sides of the fibre until it reaches the other end -at the other end it is refracted back out
56
what are important used of optical fibres
- communications (telephone, broadband internet) - medical imaging (colonoscopy, endoscope)
57
why are optical fibres good in communications
they are able to carry more information at a faster rate than electricity through copper cables
58
what are the components of an optical fibre
- optically dense core tube made of plastic or glass - lower optically dense cladding surrounding the core - an outer sheath
59
what is a step-index fibre
as type of optical fibre where the refractive index of each component increases moving from the outside to the center of the fibre
60
what is the purpose of the cladding in an optical fibre
- to increase the critical angle of the glass/cladding boundary -protect the thin core from damage and scratching - prevent signal degradation - keeps the signals secure - keeps the core separate from other fibres
61
what is pulse broadening
when the pulses emerging from an optical fibre are longer than those entering
62
what is material dispersion
when white light is used in an optical fibre causing it to separate into all the colours of the spectrum, causing the light to be dispersed so the beam gets wider and it travels down the optical fibre
63
why does material dispersion occur
- refractive index varies with wavelength - the different wavelengths of light slow down by different amounts
64
what is modal dispersion
when white light enters the optical fibre and the different wavelengths refract by different amounts. therefore different paths are taken to the other end
65
what are monomode fibres and why are they used in communications
- they are fibres where the core is narrow so wavelengths of light are confined to one path
66
how does the absorption of a signal in optical fibres occur
when the fibre absorbs part of the signals energy reducing the amplitude of the signal
67
how does pulse broadening occur in optical fibres
by modal and material dispersion, resulting in the merging if pulses
68
how do you reduce absorption in optical fibres
- use an extremely transparent core -use optical fibre repeaters
69
how do you reduce pulse broadening
- use a core that is as narrow as possible - use a monochromatic source - use optical fibre repeaters - use a single-mode fibre

a-level physics (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions