Waves Flashcards
(106 cards)
1
Q
2 types of waves
A
Transverse
Longitudinal
2
Q
All waves transfer
A
Energy from one place to another
3
Q
The particles that make up a wave
A
Oscillate(vibrate) about a fixed point
Pass the energy onto the next particles they pass the energy which also oscillate and so on
4
Q
Energy moves along but
A
Matter remains
5
Q
Transverse wave are
A
Oscillations are perpendicular to the direction of energy transfer
Slinky spring up and down
Water waves
6
Q
Longitudinal waves are
A
Oscillations are parallel to the direction of energy transfer
Slinky pulses
Eg sound wave
7
Q
Frequency
A
The number of waves passing a fixed point per second
8
Q
Amplitude
A
The maximum displacement that any particle achieves from its undisturbed positon in metres
9
Q
Wavelength
A
The distance from one point on a wave to the equivalent point on the next wave in m
10
Q
Period
A
The time taken for one complete oscillation in seconds
11
Q
When observing waves
A
Amplitude is seen as the wave height
The period is the time taken for one complete wave to pass a fixed point
12
Q
Period =
A
1/ frequency
13
Q
Amplitude indicates
A
The amount of energy a wave is carrying
14
Q
The speed of a wave is a
A
The speed at which high energy is transferred
15
Q
Wave speed is a measure of
A
How far the wave moves in one second
16
Q
Wave equation
A
Wave speed=
Frequency x wavelength
17
Q
RP
A
31
18
Q
As waves are transmitted from one medium to another
A
The speed and wavelength changes
Frequency doesn’t change
19
Q
Speed and wavelength are
A
Directly proportional
20
Q
When waves reach a boundary between one medium and another they are
A
Reflected
Refracted
Absorbed
Transmitted
Ray diagrams show this
21
Q
When construction a ray diagram
A
Ruler
Arrow on each ray
Normal needs to be drawn
Relevant angles should be labelled
22
Q
When waves are reflected at a surface
A
The angle of incidence is equal to the angle of refraction
23
Q
When a wave passes from one medium to another it can be r
A
Refracted
So changes direction
24
Q
The angle of refraction depends on
A
The angle at which the wave hits the boundary
The material
25
For light rays the way in which a material effects refraction is
It’s refractive index
26
When light travels from a material with a low refractive index to one with a higher refractive index
It bends towards the normal
27
When light travels form and area of high refractive index to an area of low
It bends away from the normal
28
Refraction is due to
The difference in the wave speed in the different media
29
When a light wave enters at an angle a medium in which it travels slower
The first part of the light wave to enter slows down
The rest of the wave stays at the high speed
This causes it to change direction towards the normal
30
Wave front diagram
Pg 32
31
Required practical
Pg 33
32
The amplitude of a sound wave relates to the
Loudness
33
The frequency and wavelength of a sound wave relate to
The pitch
| Higher frequency=higher pitch
34
Range of human hearing is
20hz—20000hz
35
Sound cns travel through
Liquid solid and air
36
Sound Is due to
Vibrations of the particles in the medium
| In a solid, these oscillations can cause the entire object to vibrate with the same frequency as the sound wave
37
The conversion of sound waves to vibrations only occurs over a limited range of frequencies
Dependent on
The structure of the objedt
38
Within the ear sound waves cause
The ear drum and other structures to vibrate and this is heard as sound
The limited range of conversion is what limits human hearing
39
Ultrasonic waves have a frequency higher than
20khz
| So can’t be heard by humans
40
When a ultrasonic wave meets a boundary between two medium
It is partially refracted
41
You can measure how far away a boundary is by
Measuring the time taken for reflective ultrasonic waves to return to a detector
42
Uses in industry
| Ultrasound
Detect defects in material without cutting into them
Eg crack air bubble or
Corrosion
43
Uses In medicine
Pre natal scanning
Detecting kidney stone and tumours
Producing images of damaged ligaments and muscles
44
Echo sounding is
The use of ultrasonic waves for detecting objects in deep water and measuring the depth of the wager
45
Echo sounding involves
Sending an ultrasound pulse into water which is then reflected back when it hits a surface
The time between the pulse being sent and the reflection being detected is used to calculate the distance travelled by the wave
46
The speed of sound in water is
1500m/s
47
To find the total distance travelled by the pulse
D=s x t
To find the depth of the water
Divide by 2
48
Two types of seismic waves produced in an earthquake
P waves— primary
S waves— secondary
49
P waves are
Longitudinal
Travel at the speed of sound
Twice as fast as S waves
Travel at different speeds through solids and liquids
50
S waves are
Transverse
| Can’t travel through liquids
51
When seismic waves are produced, the difference in time between the arrival of p waves and a waves at different detectors can provide
Evidence about the location of the earthquake and the material they have traveled through
52
During an earthquake
Seismic waves travel outwards from the earthquake and are capable of travelling all the way through the earth
Seismic waves travel in a curved path due to the different density of the earth( increase with depth)
Detectors around the earth measure when and where the different waves arrive
53
S-wave shadow zone
S waves can’t travel through the liquid outer core
This results in a large shadow zone on the opposite side of the earth to where the earthquake originated
This shadow zone provided evidence of the size of the Earths core
54
P wave shadow zones
P waves can travel through the liquid outer core
However are refracted at the boundary between the semi-solid mantle and the liquid outer core
They are refracted again at the boundary between the liquid outer core and solid inner core
These réfractions result in p wave shadow zones
This can determine the size and composition of the inner and outer core
55
Electromagnetic waves are
Transverse waves
56
All electromagnetic waves travel at
The same velocity(speed of light) in air or a vacuum
57
The electromagnetic spectrum
Low frequency, low energy waves to high frequency, high energy waves
58
Human eyes are only capable of
Detecting visible light
| A very limited range of electromagnetic waves
59
The wavelength of an electromagnetic wave effects
How it is absorbed,transmitted, reflected or refracted bu different substances
This affects its uses
60
Radio waves
Television, radio, Bluetooth
Low energy, not harmful, ideal for radio transmission
61
Microwaves
Satellite communications , cooking food
Travel in straight lines through the atmosphere
Ideal for transmitting signals to satellites in orbit and transmitting them back down to receivers
62
Infrared waves
Electric heaters, cooking foods, infrared cameras
Heaters, grills toaster etc glow red hot as electricity flows through them
This transmits infrared energy that is absorbed by the food and converted back into heat
63
Visible light
Fibre optic communication
Travels down optical fibres from one end to the other without being lost through the sides
64
Ultraviolet waves
Energy efficiency bulbs, security marking, sunbeds
In bulbs: Uv waves are produced by the gas when it is excited by the electric current
These uv waves are absorbed by the coating on the bulb which fluoresces
65
X rays
Medical imaging and treatment
Can penetrate soft tissue but not bone
A photographic plate will show shadows where bones are
66
Gamma rays
Sterilising food , treatment of tumours
Most energetic and can destroy bacteria and tumours
67
Required practical
Pg 37
68
Radio waves can be caused by
Oscillations in electrical circuits
69
The frequency of the radio wave produced matches
The frequency of the electrical oscillation
| This is how a radio signal is produced
70
When radio waves are absorbed by a conductor
They may create and alternating Current with the smae frequency as the radio wave this is how the signal is received
When this oscillation is induced In an electrical circuit it creates an electrical signal that matches the wave
71
Changes in atoms and the nuclei of atoms can result in EM waves being generated or absorbed:
Electrons moving between energy levels as a result of heat or electrical excitation can generate waves eg infrared, visible light, uv, x rays
Change in the nucleus can generate waves, an unstable nucleus can give out excess energy as gamma rays
72
Waves which have enough energy to cause hazardous effects to human body
Uv
X-rays
Gamma rays
73
UV rays can cause
Skin to age prematurely and increase risk of skin cancer
74
X rays and gamma rays are
Ionisingcan damage cells
| If absorbed by nucleus can cause gene mutation and cancer
75
A lens forms an image by
Refracting light
76
Two main types of lens
Concave
| Convex
77
Convex lens
Wider at the middle than the edges
When parallel rays of light enter they are brought to focus at the focal point
Because the light comes together it is sometimes called a converging lens
78
Focal length is
The distance from lens to the principal focus l( focal point)
79
Concave lens
Wider at the edges than the middle
Parallel rays of light enter and then spread out
Something called diverging lens
80
Convex lenses can produce
Real or virtual images
81
Concave lenses produce
Only virtual images
82
A real image is
On the opposite side of the lens to the object and can be projected onto a screen
83
A virtual image is
On the same side as the object and can only be seen by looking through the lens
84
When drawing a ray diagram
Draw the principal axis (horizontal line straight through the lens)
Draw the correct lens symbol
Mark the principal focus on either side bu drawing a dot and labelling it f
Mark the position of the object as an arrow standing on the principal axis
Draw the light rays
85
Drawing concave and convex light rays
Pg 39
86
Magnification is
A ratio
Image height/
Object height
No units
87
Visible light is
Electromagnetic waves that can be detected by the human eye
88
When light arrive at and hits / incident on an object it can be
Absorbed
Reflected
Transmitted
89
Specular reflection is
Reflection by a smooth surface in a single direction
90
Diffuse réflection
Reflection off a rough surface that scatters
91
All objets are eithe
Transparent- transmit light clearly
Translucent- transmit light scattered not clearly
Opaque- reflect or absorb light no light passes through
92
Each colour within the visible spectrum has
It’s own narrowband of wavelength and frequency
93
When an opaque object appears coloured
It is reflecting light of that particular wavelength
It is absorbing other wavelengths.
94
Objects appear white
All wavelengths are reflected equally
95
Objects appear black
All wavelengths absorbed
96
Coloured filters work by
Absorbing some wavelengths and not others
Variety of different effects can be seen
97
All bodies (objects)
Emit and absorb infrared radiation
98
The rate at which an object emits radiation depends on
The nature of its surface and the temperature
99
A perfects Black body
Absorbs all of the infrared radiation incident on it
Does not reflect or transmit any infrared radiation
Best possible emitter
100
The temperature of an object or body determines
The rate at which it emits radiation
The wavelength of the radiation it emits
101
As the temperature of a body increases
The amount of radiation an object emits at all wavelengths increases
102
When an object is heated
First glows red hot
| As it gets hotter it emits even shorter wavelength and becomes whiter
103
The temperature of an object is relayed to
The balance between radiation absorbed and radiation emitted
104
On a sunny day
Ground will increase in temperature when the sun comes out as it absorbs radiation faster than it is emitted
As the ground gets warmer the rate at which it emits radiation will increase
Eventually it will become equal and becomes a constant temperature
105
The temperature of the earth depend on
How much energy it receives from the sun
How much energy is reflected back into space
How much energy it emits to space
106
The earths atmosphere also effects
How much of the radiation emitted from the surface escapes into space
