Waves Flashcards
(108 cards)
1
Q
Which way do waves transfer energy?
A
The way they are travelling
2
Q
What do waves have?
A
- amplitude
- wavelength
- frequency
3
Q
What is the amplitude of a wave ?
A
The maximum displacement of a point of the wave from its undisturbed position
4
Q
What is wavelength?
A
The distance between the same point on two adjacent waves
Trough to trough
Crest to crest
5
Q
What is frequency?
A
The number of complete waves padding a certain point per second
6
Q
What is frequency measured in ?
A
Hertz. (Hz)
7
Q
What is the period of a wave?
A
The amount of time it takes for a full cycle of the wave to pass a point
8
Q
How do u calculate the period of a wave?
A
Period = 1
—————
Frequency
9
Q
What is the equation for wave speed ?
A
Wave speed = frequency x wavelength
10
Q
What type of waves are sound waves ?
A
Longitudinal
11
Q
What type of waves are water ripples ?
A
Transverse
12
Q
What are longitudinal waves ?
A
The oscillations are parallel to the direction of energy transfer
Like pushing a spring
13
Q
What are transverse waves?
A
The oscillations are perpendicular to the direction of energy transfer
A spring wiggles from to side
14
Q
What is wave speed ?
A
The speed at which energy is being transferred through a medium
15
Q
What do longitudinal waves show?
A
- compression
- rarefaction
16
Q
How do u measure the speed of sound ?
A
With an oscilloscope
17
Q
How do u measure the speed of water ripples ?
A
Using a strobe light
18
Q
What is the rule for all reflected waves ?
A
Angle if incidence = Angle of refraction
19
Q
What is the angle of incidence ?
A
The angle between the incoming wave and the normal
20
Q
What is the angle of reflection ?
A
The angle between the reflected ray and the normal
21
Q
What is the normal ?
A
And imaginary line that’s perpendicular to the surface at the point of incidence
Usually A dotted line
22
Q
What is the point of incidence ?
A
The point where the wave hits the boundary
23
Q
When does specular reflection happen?
A
When a wave is reflected in a single direction by a smooth surface
Creates a clear reflection
24
Q
What is diffuse reflection?
A
When a wave is reflected by a rough surface
Rays are scattered in lots of different directions
25
What is refraction ?
When light waves are bent when they enter a new media
26
What does the extent of refraction depend up on?
How much the wave speeds up or slows down
This depends on the density of the two materials
27
Which way does a wave bend if it speeds up?
Away from the normal
28
Which way does the wave bend if it slows down ?
Towards the normal
29
What happens to frequency and wavelength when a wave is refracted
Wavelength changes
Frequency stays the same
30
What is optical density of a material ?
A measure of how quickly light can travel through it
The higher the optical density, the slower the wave travels
31
What does the amount of light reflected depend on ?
The smoothness if the surface
32
What type of waves are EM waves ?
Transverse
They transfer energy from a source to an absorber
33
What is the electromagnetic spectrum ?
- radio waves
- micro wave
- Infared
- visible light
- ultra violet
- x rays
- gamma rays
34
What happens to the frequency as u go along the EM spectrum ?
It increases
35
What happens to the wavelength as u go along the EM spectrum ?
It decreases
36
How are radio waves made?
By oscillating electric and magnetic fields
37
Waves can be ...
- Absorbed
- Transmitted
- Reflected
38
What do electromagnetic waves form ?
A continuous spectrum and a,l types of electromagnetic wave travel at the same velocity through a vacuum
39
Which electromagnetic waves do our eyes detect ?
Visible light
40
What are alternating currents made up of ?
Oscillating charges
As charges oscillate the produce oscillating electric and magnetic fields
Electromagnetic waves
41
How do leases form images ?
By refracting light and changing its direction
42
Describe a convex lease and how it works ?
Bulges outwards
Causes rays of light parallel to the axis to be brought together at the principle focus
Converge
43
What is the axis of a lens ?
The line passing through the middle of the lens
44
Describe a concave lens and how it works ?
It caves inwards
It causes rays of light parralel to the axis to spread out
Diverge
45
What is the principal focus of a concave lens ?
The point where rays hitting the lens parallel to the axis appear
46
What is the focal length ?
The distance from the centre lens to the principle focus
47
What is the principle focus of a convex lens ?
Wher rays hutting the lens parallel to the axis all meet
48
What images can menses produce ?
Real or virtual
49
What is a real image?
Where the light from an object comes together to form an image in a screen
Like the image on an eyes retina
50
What is a virtual image “
When the rays are diverging so the light from the object appears to be coming from a completely different place
Looking in a mirror
51
How should u describe an image ?
- How big it is
- if it is upright or inverted
- if it is real or virtual
52
What is the equation for magnification ?
Magnification = image height
—————-
Real height
53
What are the units for image height and real height?
Me or cm
54
What lens do magnifying glasses use ?
Convex
55
What is visible light made up of ?
A range of colours
56
What do the colour and transparency’s of waves depend on?
Absorbed wave lengths
57
What do red apples reflect “
Red waves lengths
Absorbs all the other colours
58
What do white objects reflect?
All wavelengths of visible light
59
What do transparent objects reflect ?
Objects transmit the light
Some can pass through
60
What do black objects reflect ?
They absorb all wavelengths of visible light
61
What colour is the object that absorbs all light ?
Black
62
What colour is the object that reflects all light ?
White
63
What are objects that transmit all light ?
Transparent or translucent
64
What’s does transparent mean ?
You can see through
65
What does translucent mean ?
You can partially see through
66
What does opaque mean ?
You can’t see through it
67
What do colour filters do ?
Filter out different wavelengths
So only certain colour are transmitted
68
Name the two main types of lens ?
Convex and concave
69
Which lens creates a real and virtual image
Convex
70
Where is Infrared radiation emitted from?
From the surface of all objects
71
What is a prefect black body ?
An object that absorbs all of the radiation incident on it
Doesn’t reflect or or transmit any radiation
72
What are radio wave mainly used for ?
Communication
73
What is the wavelength of a radio wave ?
Longer than 10cm
74
What uses micro waves .?
Satellites
| Microwave ovens
75
What is infrared radiation used for ?
Monitoring temperature
Cooking
Electric heaters
Infrared cameras
76
What does absorbing infared radiation do to an object ?
Make it hotter
77
What is visible light used for ?
Fibre optic cables to transmit data
78
What are optical fibres?
Thin glass or plastic fibres that can carry data over long distances as pulses of visible light
79
What is ultraviolet used for ?
- fluorescent light
- security pens
- sun tanning
- energy Efficient lamps
80
What produces ultra violet light ?
The sun
81
What are X-rays and gamma rays used for?
Medical purposes
82
What are the dangers of UV light ?
- sunburn
- skin ageing permanently
- blindness
- unversed dish of skin cancer
83
What are the dangers of gamma rays and X-rays ?
They carry enough energy to knock off electrons
Causes gene mutation, cell destruction and cancer
84
What is radiation dose measured in ?
Sieverts
1000mSv =1Sv
85
What surfaces are best for absorbing and emitting radiation ?
Black is better than white
Matt is better than shiny
86
What does the intensity and distribution of wavelengths emitted by an object depend on ?
The objects temperature
87
What does the overall temperature of the earth depend on ?
The amount of radiation it reflects, absorbs and emits
88
What does a absorbed radiation mean ?
A rose in temperature
89
What causes sound waves ?
Vibrating objects
90
Where does sound travel fastest ?
In solids
91
What can’t sound travel in space ?
It’s mostly a vacuum
No particles to vibrate with
92
When do u here sound?
When your ear drum vibrates
93
How do we hear sound ?
Sound waves reach your ear drum and cues it to vibrate
These vibrations are passed on to the ossicles, through the semicircular canals and to the cochlea
The cochlea turns these vibrations into electrical signals
The electrical signals are sent to your brain and allow you to sense the sound
94
What is the range of sound a human ear can hear ?
20hz - 20khz
95
What limits the hearing of humans?
Size and shape of our ear drum
96
What is an echo?
Sound waves reflected by hard flat surfaces
97
What is ultrasound ?
Frequencies higher than 20 000Hz
98
What is specular reflection ?
Reflection from a smooth surface in a singular direction
99
What is diffuse reflection ?
Reflection from a rough surface causes scattering
100
What is the colour of an object determined by?
Which wavelengths are most strongly reflected
101
What happens tothe amount of infared radiation as the object gets hotter ?
It increases
The hotter the body the more infrared radiation
102
What are the uses of ultras sound ?
- scanning foetuses and other parts of the body
- detecting flaws in materials
- underwater exploration
103
How do ultrasounds work
Waves enter a material and are partially reflected back when they meet a boundary between two two different media
104
What causes seismic waves ?
Earthquakes and explosions
105
What detects seismic waves ?
Seismometers
106
What are the two types of seismic waves ?
P-waves
S-waves
107
Give the properties of a p-wave ?
- longitudinal
- travel through solids and liquids
- faster than s-waves
- refract as density’s change
- pass through the earths core
108
Give the properties if s-waves
- transverse
- can’t travel through liquids or gases
- slower than p-waves
- can’t pass through the earths core
