P6- Waves Flashcards
(107 cards)
1
Q
What does a wave transfer
A
Energy from one place to another
2
Q
What causes a wave
A
A vibration
3
Q
What is the definition of a transverse
A
The vibration causing a transverse wave is perpendicular to the direction of travel wave is parallel
4
Q
What is the definition of a longitudinal wave
A
The vibration causing a longitudinal wave is parallel to the direction of travel of the wave
5
Q
Give three examples of longitudinal waves
A
Sound, ultrasound and primary earthquake (p) waves
6
Q
Give three examples of transverse waves
A
Water waves, all Em waves and secondary earthquake(s) waves
7
Q
What is a compression
A
A compression is when particles in a longitudinal wave are closest together
8
Q
What is a rarefaction
A
A rarefaction is when particles in a longitudinal wave are furthest apart
9
Q
What is the amplitude
A
The amplitude is the maximum displacement of a wave from its equilibrium position
10
Q
What is the wavelength
A
The distance from a point on one wave to the same point on the next wave
11
Q
What is the frequency
A
The number of waves passing a point each second
12
Q
What are the units of wave speed, wavelength and frequency
A
Wave speed-m/s, wavelength-m, frequency - Hz
13
Q
What is the wave speed equation
A
v= f x λ Speed = Wavelength x Frequency
14
Q
What speed do EM waves travel at
A
300 000 000 m/s
15
Q
What speed does sound travel at
A
330 m/s
16
Q
List the EM waves in order from longest to shortest wavelength
A
Radio, microwave, infra-red, visible, ultra-violet, x-ray, gamma
17
Q
Which EM wave has the highest frequency
A
Gamma
18
Q
which EM wave has the most energy
A
Gamma
19
Q
Which three EM waves are ionising
A
Ultra-violet, x-ray and gamma
20
Q
What happens when light travels from air into a glass block
A
It refracts towards the normal as glass is more dense than air
21
Q
What happens when light travels from a glass block into air
A
It refracts away from the normal as air is less dense than glass
22
Q
What is the law of reflection
A
The angle if incidence is equal to the angle of reflection
23
Q
What is the danger of ultra-violet light
A
Can cause skin to age prematurely and increase the risk of skin cancer
24
Q
What is the danger of X-rays and gamma ray
A
X- rays and gamma rays are ionising radiation that can cause the mutation of genes and cancer
25
What are radio waves used for
Television and radio transmission
26
What are microwaves use for
Satellite communication ( as they can travel through ionosphere) and for cooking food
27
What is infra-red used for
Electrical heaters, cooking food and infrared cameras
28
What is visible light used for
Fibre optic communications (and our vision)
29
What is ultra-violet used for
energy efficient lamps, sun tanning
30
What are X-rays used for
Medical imaging and security scanning
31
What are gamma rays used for
Medical treatment (radiotherapy)
32
What is the equation for time (waves)
1 ÷ f (Hz)
33
What are the two types of waves?
1. Transverse
| 2. Longitudinal
34
What is a transverse wave?
A wave for which the oscillations are
perpendicular to the direction of energy
transfer.
35
What is a longitudinal wave?
A wave for which the oscillations are
parallel to the direction of energy
transfer.
36
Give two examples of transverse waves.
1. Electromagnetic waves
| 2. Seismic s-waves
37
Give two examples of longitudinal waves.
1. Sound waves
| 2. Seismic p-waves
38
What are the two parts of a longitudinal wave called?
Compressions and rarefactions.
39
What is a wave’s amplitude?
The maximum displacement of a point
| on a wave from its undisturbed position.
40
What is wavelength?
```
● The distance from a point on a wave to
the same position on the adjacent
wave
● Most commonly peak to peak or
trough to trough
```
41
What is the frequency of a wave?
The number of waves that pass a given
| point each second.
42
What is the unit used for frequency?
Hertz, Hz
43
What is meant by a frequency of 200Hz?
200 waves pass a given point each
| second
44
What is wave speed?
The speed at which the wave moves or
at which energy is transferred through a
medium.
45
What does a wave transfer?
Energy
46
State the equation used to calculate wave speed.
| Give appropriate units.
Wave Speed = Frequency x Wavelength
Speed (m/s), Frequency (Hz),
Wavelength (m)
47
What word is used to describe when a wave
| bounces off a surface?
Reflection
48
How do sound waves travel through a solid?
The particles in the solid vibrate and
transfer kinetic energy through the
material.
49
What is the frequency range of human hearing?
20 Hz - 20kHz
| 1kHz = 1000 Hz
50
What are ultrasound waves?
Waves which have a frequency higher
than the upper limit of human hearing
(20kHz)
51
Give an example use for ultrasound waves?
Medical or industrial imaging.
52
What natural event causes seismic waves to be
| produced? What types are produced?
● Earthquakes
● They produce both P-waves and
S-waves
53
State a difference between the mediums that
| P-waves and S-waves can travel through.
● P-waves travel through both solids and
liquids
● S-waves only travel through solids
(not liquids)
54
What technique is used to detect objects in deep
| water and measure water depth?
● Echo sounding
● High frequency sound waves are emitted,
reflected and detected
● Time difference between emission and detection,
alongside wave speed, are used to calculate
distances
55
What type of spectrum do electromagnetic waves
| form?
A continuous spectrum.
56
Order the types of electromagnetic radiation from
| lowest to highest frequency.
```
● Radio waves
● Microwaves
● Infrared
● Visible Light
● Ultraviolet
● X-rays
● Gamma Rays
```
57
How do the speeds of EM radiation differ in a
| vacuum and in air?
Electromagnetic waves all travel at the
| same speed in a vacuum and in air
58
What property of waves in different mediums causes
| refraction?
● Velocity
● Wave speed is slower in denser
materials, causing refraction
59
In which direction (relative to the normal) do waves
| refract when entering a denser medium?
● They bend towards the normal
● The angle of refraction is less than the
angle of incidence
60
What type of waves can be produced by oscillations
| in an electrical circuit?
Radio waves.
61
How can radio waves create an alternating current in
| a circuit?
When radio waves are absorbed, they
can induce oscillations in a circuit with
the same frequency as the waves
themselves.
62
Where do gamma rays originate from
They originate from changes in the
| nuclei of atoms.
63
What health effects can ultraviolet waves cause
● They can cause the skin to age
prematurely
● The can increase the risk of
developing skin cancer
64
What health effects can X-rays and Gamma rays
| cause
● They are ionising radiation so can
cause mutations in genes
● They can lead to increased risk of
developing various cancers
65
Give three practical uses for infrared radiation
1. Electrical heaters
2. Cooking food
3. Infrared cameras
66
Give two practical uses for microwave radiation
1. Satellite communications
| 2. Cooking food
67
Give two practical uses for radio waves
1. Television transmission
| 2. Radio transmission
68
What wave phenomenon is used by lenses to form
| an image?
Refraction.
69
How does a convex lens form an image?
Parallel rays of light are refracted and
brought together at a point known as the
principal focus.
70
What is meant by the focal length of a lens?
The distance from the lens to the
| principal focus
71
What is the difference between the image produced
| by a convex and a concave lens?
● Convex lenses can produce real or
virtual images
● Concave lenses can only produce
virtual images
72
Why does magnification not have a unit?
● It is the ratio between image height
and object height
● Ratios do not require units
73
What determines the colour of visible light waves
The wavelength and frequency of the
| light waves.
74
What colour of visible light has the highest
| frequency?
Blue
75
What colour of visible light has the largest
| wavelength?
Red
76
What is meant by the term ‘specular reflection’
Reflection from a smooth surface in a
| single direction.
77
What is meant by the term ‘diffuse reflection’?
Reflection from a rough surface which
| causes scattering.
78
How does a red colour filter work?
```
● A red filter absorbs all wavelengths of
light other than those in the red range
of the spectrum
● This means only red light passes
through the filter
```
79
What determines the colour of an opaque object
```
● Different objects reflect different
wavelengths of light by different
amounts
● The wavelengths that are most
strongly reflected determine the colour
```
80
What happens to the wavelengths of light that aren’t
| reflected by an opaque object?
Any wavelengths that aren’t reflected are
| absorbed by the object.
81
What colour does an object appear if all wavelengths
| are reflected by equal amounts
White
82
What colour does an object appear if all wavelengths
| are absorbed?
Black
83
What do all bodies (objects) emit and absorb?
Infrared radiation
84
What happens to the quantity of infrared radiation
| emitted by an object as temperature increases?
The hotter the object, the more infrared
| radiation it will emit.
85
What is a perfect black body
An object that absorbs all of the radiation
| that is incident upon it.
86
How much radiation does a perfect black body
| reflect or transmit
None.
87
Why is a perfect black body the best possible emitter
| of radiation?
● It is a perfect absorber since it absorbs
all radiation incident on it
● A perfect absorber is also a perfect
emitter
88
Other than the intensity of radiation emitted, how
does increasing the temperature of an object affect
its emissions?
The wavelength distribution of any
emission is dependent on the object’s
temperature.
89
What can be said about the rates of emission and
| absorption for a body at constant temperature
The body is absorbing and emitting
| radiation at the same rate
90
What can be said about the rates of emission and
| absorption for a body increasing in temperature
The body is absorbing radiation faster
| than it is emitting it
91
Give two factors that affect the temperature of the
| Earth.
1. The Earth’s rate of absorption and
emission of radiation
2. The amount of reflection of radiation
into space
92
Define a perfect black body
An object that absorbs al of the radiation that hits it
93
A white star expands and its surface appears redder in colour. Describe how the surface temperature of the star has changed
The radiation emitted covers a large range of wavelengths
94
Electromagnetic radiation from the Sun affects the temperature of the Earth. Explain, with respect to the radiation emitted by the Sun and Earth, how the temperature of the Earth remains approximately constant (6)
○ During the day, the half of the Earth which is facing the Sun is hit by radiation emitted by the sun
○ Some of this radiation is absorbed by the atmosphere and the Earth's surface
○ Because of this, the amount of radiation absorbed during the day is greater than the amount that is emitted
○ This causes an increase in local temperature
○ The half of the Earth which is facing away from the Sun has no radiation from the Sun hitting it - it is night time.
○ This half of the Earth absorbs very little radiation but emits radiation at its usual rate
○ So at night time radiation is emitted at a much higher rate than it is absorbed.
○ This causes a decrease in local temperature
○ Throughout each full cycle of day and night, one half of the Earth will be increasing in temperature and the other half will be decreasing in temperature
○ Overall, these local temperature changes balance out, and so the average temperature of the Earth remains roughly constant
95
How do lenses focus light
By refracting
96
Lenses can make images smaller or bigger. This is called ...
Magnification
97
Lenses can be inverted (make them _)
Upside down
98
Lenses can make_or _images
Real
| Virtual
99
What does real mean (in terms of lenses)
Can be projected onto a surface
100
What does virtual mean (in terms of lenses)
Cannot be projected onto a surface
101
What is white light made up of
Al the colours on the colour spectrum
102
_refracts the least and has the _ wavelength
Red
| Longest
103
What is dispersion
When we can see the individual colours in the spectrum
104
Coloured objects only _ their own colour light
Reflect
105
Explain how ultrasonic waves are used to produce the image of an unborn baby
(partly) reflected when they hit a (boundary between two) different media
or substance or tissue
time taken for reflected wave (to return) is used to produce the image
106
Give a use for ultrasounds that isn't to do with a baby
```
cleaning a delicate mechanism/jewellery
welding plastics
cutting textiles
mixing emulsion paints
sonar
motion sensors (in burglar alarms)
removing dental plaque
industrial quality control
breaking up kidney stones
treating injuries
```
107
Ultrasound can be used in the industry for detecting internal cracks in metal. State two features of ultrasound
• humans cannot hear ultrasound
• it has a very high frequency / pitch
do not credit just ‘has a high frequency / pitch’
• above the (upper) limit for humans / above 20 000 Hz
