Waves Flashcards
1
Q
What are the two types of waves?
A
Transverse and Longitudinal
2
Q
Define transverse waves.
A
Waves where the points along its length vibrate at 90 degrees to the direction of energy transfer
3
Q
What is the energy transfer direction in transverse waves?
A
Perpendicular to wave motion
4
Q
List examples of transverse waves.
A
- Ripples on the surface of water
- Vibrations in a guitar string
- S-waves (a type of seismic wave)
- Electromagnetic waves (such as radio, light, X-rays)
5
Q
Define longitudinal waves.
A
Waves where the points along its length vibrate parallel to the direction of energy transfer
6
Q
What is the energy transfer direction in longitudinal waves?
A
In the same direction as the wave motion
7
Q
List examples of longitudinal waves.
A
- Sound waves
- P-waves (a type of seismic wave)
- Pressure waves caused by repeated movements in a liquid or gas
8
Q
What are compressions and rarefactions in longitudinal waves?
A
- Compressions: points close together
- Rarefactions: points spaced apart
9
Q
What is amplitude?
A
The distance from the undisturbed position to the peak or trough of a wave
10
Q
What is wavelength?
A
The distance from one point on the wave to the same point on the next wave
11
Q
What is frequency?
A
The number of waves passing a point in a second
12
Q
What is the symbol for frequency?
A
f
13
Q
What is the time period of a wave?
A
The time taken for a single wave to pass a point
14
Q
What is the wave speed equation?
A
v = f × λ
15
Q
What does the symbol ‘v’ represent in the wave equation?
A
Wave speed in metres per second (m/s)
16
Q
What does the symbol ‘λ’ represent?
A
Wavelength in metres (m)
17
Q
How can the speed of sound be measured using echoes?
A
By timing how long it takes for sound to travel to a wall and back
18
Q
What is the method for measuring wave speed in water?
A
Creating ripples in a calm water surface and timing how long it takes for the ripple to reach a distance
19
Q
True or False: Waves transfer matter along with energy.
A
False
20
Q
What is the relationship between frequency and time period?
A
f = 1/T
21
Q
Fill in the blank: The distance travelled by a wave each second is called the _______.
A
[wave speed]
22
Q
What is the unit of measurement for frequency?
A
Hertz (Hz)
23
Q
What does the term ‘wavefront’ refer to?
A
The representation of waves viewed from above
24
Q
What is the effect of a medium on the transmission of transverse waves?
A
Transverse waves can move in solids and on the surfaces of liquids but not inside liquids or gases
25
What is a key characteristic of longitudinal waves in a vacuum?
They cannot move in a vacuum since there are no particles
26
What is the definition of amplitude in the context of water waves?
Amplitude = The distance from the undisturbed position to the peak or trough of a wave
## Footnote
Amplitude is a key characteristic of waves, indicating their energy level.
27
What is the definition of wavelength?
Wavelength = The distance from one point on the wave to the same point on the next wave
## Footnote
Wavelength is critical for determining the properties of waves.
28
Which arrow represents the amplitude of a water wave in the diagram?
Arrow D
29
Which arrow represents the wavelength of a water wave in the diagram?
Arrow C
30
True or False: Sound waves are longitudinal waves.
True
31
In which medium do sound waves travel fastest?
Solids
32
In which medium do sound waves travel slowest?
Gases
33
What three properties of sound waves change when they move from one medium to another?
* Wave speed
* Frequency
* Wavelength
34
What happens to the wavelength of a sound wave when it moves from a denser medium to a less dense medium?
The wavelength decreases
35
What happens to the frequency of a sound wave when it moves from a denser medium to a less dense medium?
The frequency stays the same
36
How does temperature affect the speed of sound in air?
On warm days, the speed of sound increases; on cold days, it decreases.
37
What is the formula for calculating wave speed?
Wave Speed = Frequency × Wavelength (v = fλ)
38
What is the independent variable in the experiment measuring wave properties in a ripple tank?
Frequency, f
39
What is the dependent variable in the experiment measuring wave properties in a ripple tank?
Wavelength, λ
40
Fill in the blank: Systematic errors can occur in experiments due to difficulties in identifying the _______.
wavefronts
41
What is the law of reflection?
The angle of incidence = The angle of reflection
42
What occurs when a wave hits a boundary between two media and does not pass through?
Reflection
43
What happens to light waves when they encounter a rough surface?
They scatter in all directions.
44
What is absorption in the context of wave interactions with materials?
Energy is transferred from the wave into the particles of a substance.
45
What is the relationship between the angle of incidence and the angle of reflection?
They are equal.
46
In the experiment investigating reflection, what is the independent variable?
Angle of incidence, i
47
In the experiment investigating refraction, what is the dependent variable?
Angle of refraction, r
48
What equipment is used to measure the angle of incidence and reflection?
Protractor
49
What occurs when a wave passes through a substance?
Transmission
50
What is a characteristic of waves that are transmitted through a material?
They may be partially absorbed.
51
What does it mean if an object appears red in terms of light absorption?
Only red light has been reflected; all other frequencies have been absorbed.
52
What should be done to improve the accuracy of frequency measurements in a ripple tank?
Measure across a longer time period and divide the number of waves by the time.
53
What safety consideration should be taken when working with water and electricity?
Care should be taken to avoid electric shock.
54
What is the angle of incidence represented by?
i
55
What is the dependent variable in the refraction experiment?
Angle of refraction, r
56
What are the control variables in the refraction experiment?
* Use of the same perspex block
* Width of the light beam
* Same frequency / wavelength of the light
57
What is the first step in the method for investigating refraction?
Place the glass block on a sheet of paper and carefully draw around the block
58
What happens to light rays entering a perspex block?
The light ray refracts towards the central line (i > r)
59
What happens to light rays exiting a perspex block?
The light ray refracts away from the central line (i < r)
60
What occurs when the angle of incidence is 90° to the perspex block?
The light ray does not refract; it passes straight through the block (i = r)
61
What is a systematic error in the refraction experiment?
An error could occur if the 90° lines are drawn incorrectly
62
How can random errors be minimized in the refraction experiment?
* Use a sharpened pencil to mark in the middle of the beam
* Use a protractor with a higher resolution
63
What safety considerations should be taken during the refraction experiment?
* The ray box light could cause burns if touched
* Looking directly into the light may damage the eyes
* Keep all liquids away from electrical equipment
64
What are sound waves?
Vibrations of air molecules
65
What type of wave is sound classified as?
Longitudinal wave
66
What are the two main components of the human ear that transfer sound waves?
* The eardrum
* Three small bones
67
What is the range of frequencies that a human can hear?
20 Hz to 20 000 Hz
68
What is echo sounding used for?
To detect the ocean floor
69
What is the definition of ultrasound?
Sound waves with a frequency above the human hearing range of 20 000 Hz
70
What happens when ultrasound meets a boundary between two media?
* Partially reflected
* Partially transmitted
* Partially absorbed
71
How is the depth of water determined using echo sounding?
The distance the wave travels is twice the depth of the ocean
72
What is the formula for calculating distance using wave speed and time?
x = v × t
73
What are P-waves?
Longitudinal waves that can pass through solids and liquids
74
What are S-waves?
Transverse waves that can only pass through solids
75
What type of wave is produced by earthquakes?
* P-waves (primary waves)
* S-waves (secondary waves)
76
What is infrasound?
Sound below the frequency of human hearing (<20 Hz)
77
What can the reflection of sound waves indicate about a structure?
It can help identify hidden structures based on the amount of sound reflected and the speed of the wave
78
What is one use of ultrasound in medicine?
To construct images of a foetus in the womb
79
What is the role of ultrasound transducers?
* Emit ultrasound
* Receive ultrasound
80
How can ultrasound be used in industry?
* Check for cracks inside metal objects
* Generate images beneath surfaces
81
What type of waves are unable to pass through the Earth’s liquid outer core?
Transverse S-Waves
## Footnote
S-waves, or Secondary waves, are transverse and can only travel through solids.
82
What are the properties of S-waves?
S-waves = Secondary waves, slower speed, transverse, go through solids only
## Footnote
S-waves arrive second in seismic events.
83
What are the properties of P-waves?
P-waves = Primary waves, faster speed, longitudinal, go through liquids and solids
## Footnote
P-waves arrive first in seismic events.
84
What is the maximum depth humans have drilled into the Earth?
12.2 km
## Footnote
This is significantly less than the Earth's radius, which is over 6000 km.
85
What evidence do seismic waves provide about the Earth's interior?
They suggest the mantle is solid and the outer core is liquid
## Footnote
Only P-waves are detected on the opposite side of an earthquake, indicating S-waves cannot penetrate the outer core.
86
What do the shadow zones of seismic waves indicate about the Earth's inner core?
The inner core is solid
## Footnote
The size and positions of shadow zones suggest large refraction, indicating a solid inner core.
87
Fill in the blank: The two main discoveries from seismic waves are related to the _______ and the _______.
mantle and outer core
## Footnote
These discoveries help to understand the state of different layers of the Earth.
88
True or False: S-waves can travel through both liquids and solids.
False
## Footnote
S-waves can only travel through solids.
89
What happens to seismic waves at the boundary between different layers of the Earth?
Refractions occur, causing shadow zones
## Footnote
These shadow zones indicate areas where seismic waves do not travel.
90
What are electromagnetic (EM) waves?
Transverse waves that transfer energy from the source of the waves to an absorber
## Footnote
EM waves are characterized by their ability to travel through a vacuum and all travel at the same speed in a vacuum.
91
List the properties shared by all electromagnetic waves.
* All are transverse
* Can travel through a vacuum
* Travel at the same speed in a vacuum
## Footnote
These properties are fundamental to understanding the nature of EM waves.
92
What is the electromagnetic spectrum?
An arrangement of electromagnetic waves based on their wavelengths or frequencies
## Footnote
The spectrum ranges from long wavelength (low frequency) to short wavelength (high frequency).
93
What is visible light?
The range of wavelengths which are visible to humans
## Footnote
Visible light constitutes only 0.0035% of the entire electromagnetic spectrum.
94
Which color has the longest wavelength in the visible spectrum?
Red
## Footnote
Red light also has the lowest frequency and energy compared to other colors in the spectrum.
95
Which color has the shortest wavelength in the visible spectrum?
Violet
## Footnote
Violet light has the highest frequency and energy in the visible spectrum.
96
Fill in the blank: Radiation with higher energy is _______.
[highly ionising and harmful to cells and tissues, causing cancer]
## Footnote
Examples include UV, X-rays, and gamma rays.
97
Fill in the blank: Radiation with lower energy is _______.
[useful for communications and less harmful to humans]
## Footnote
Lower energy radiation includes radio waves and microwaves.
98
What happens to electromagnetic waves when they move from one medium to another?
They might be transmitted, absorbed, reflected, or refracted
## Footnote
The interaction depends on the wavelength of the waves and the material.
99
What is refraction?
The bending of waves as they enter a different medium at an angle
## Footnote
Refraction occurs due to a change in speed of the waves in different substances.
100
How does light behave when passing from a less dense to a more dense medium?
It bends towards the normal
## Footnote
This bending occurs because the light slows down when entering the denser medium.
101
What is the independent variable in the investigation of infrared radiation?
Colour
## Footnote
Different colors of surfaces are used to observe their effect on temperature.
102
What are the control variables in the infrared radiation experiment?
* Identical flasks (except for color)
* Same amounts of hot water
* Same starting temperature of the water
* Same time interval
## Footnote
Controlling these variables ensures valid results.
103
What can happen when an EM wave hits an atom?
* It can be absorbed
* It can be emitted
## Footnote
Electrons can move between energy levels, absorbing or emitting EM waves.
104
How are radio waves produced?
By connecting an antenna to a high frequency alternating current (a.c.) power source
## Footnote
The oscillation of charge in the a.c. circuit generates radio waves.
105
True or False: The frequency of a wave changes when it refracts.
False
## Footnote
Only the speed and wavelength change during refraction; frequency remains constant.
106
What is the method for investigating infrared radiation?
Set up identical flasks painted different colors, fill with hot water, and measure temperature changes over time
## Footnote
This method allows for comparison of heat loss based on surface color.
107
What is the relationship between temperature and thermal radiation emitted by objects?
Hotter objects emit more thermal radiation
## Footnote
The intensity and wavelength of emitted radiation depend on the temperature.
108
What produces radio waves in a transmitting antenna?
The charge from the alternating current oscillates up and down the antenna
## Footnote
This oscillation creates radio waves that can be absorbed by a receiving aerial.
109
How does a receiving aerial work?
The metal aerial absorbs the radio waves, creating an alternating current with the same frequency as the transmitted wave
## Footnote
This process allows for the reception of the transmitted signal.
110
What happens to the energy of electromagnetic (EM) waves as frequency increases?
The energy increases, becoming large enough to ionise atoms
## Footnote
Ionisation can lead to hazardous effects on human tissue.
111
What type of radiation can ionise atoms?
Ultraviolet, X-rays, and gamma rays
## Footnote
These types of radiation can damage cells and cause mutations.
112
What is radiation dose defined as?
A measure of the risk of harm resulting from an exposure of the body to ionising radiation
## Footnote
Radiation dose is crucial for assessing potential health risks.
113
How is radiation dose measured?
In sieverts (Sv), commonly in millisieverts (mSv) where 1 Sv = 1000 mSv
## Footnote
1 Sv is a very large amount of radiation.
114
What is the typical background radiation exposure per year?
About 1.5 to 3.5 mSv per year
## Footnote
This is considered normal exposure for individuals.
115
What is the effect of microwaves on water molecules?
Certain frequencies of microwaves are absorbed by water molecules, posing a risk of internal heating
## Footnote
This is particularly concerning for living organisms that contain water.
116
What is the relationship between wavelength and the danger of electromagnetic waves?
Electromagnetic waves become more dangerous the shorter their wavelength
## Footnote
For example, radio waves have no known harmful effects, while gamma rays can cause cancer.
117
What can high levels of ultraviolet (UV) exposure cause?
Severe eye damage and skin cancer
## Footnote
Good quality sunglasses and sunscreen can help mitigate these risks.
118
What precautions do doctors take when using X-rays?
Doctors leave the room to avoid unnecessary exposure
## Footnote
X-rays are kept at minimum levels to reduce risk.
119
What are radiation badges used for?
To monitor exposure to radiation for individuals working closely with radiation
## Footnote
Medical professionals like radiographers commonly use them.
120
What is a known risk associated with mobile phone use?
Possible internal heating at sufficiently high energies
## Footnote
This is due to the microwaves emitted by mobile phones.
121
What correlation was found in studies regarding mobile phone use and male fertility?
Negative correlation: the more hours a mobile phone is used each day, the lower the sperm count
## Footnote
This correlation suggests potential impacts on male reproductive health.
122
List some factors that could affect sperm count.
* High-stress environment
* Exposure to heat
* Sedentary lifestyle
* Health problems affecting fertility
* Medication
* Obesity
* Smoking / alcohol / drug intake
* Diet
* Age
## Footnote
These factors should be considered when evaluating the effects of mobile phone use.
123
What are some applications of electromagnetic waves?
Variety of uses including communication, medical imaging, and heating
## Footnote
Each type of EM wave has specific applications based on its properties.
124
What properties determine the suitability of different EM waves for specific purposes?
* Penetrating ability
* Energy
* Frequency
## Footnote
These factors influence how EM waves are utilized in various applications.
125
What is a lens?
A piece of equipment that forms an image by refracting light
126
What are the two types of lenses?
* Convex
* Concave
127
What is the principal focus of a convex lens?
The point where parallel rays of light are brought to a focus
128
What is another name for a convex lens?
Converging lens
129
What does the focal length of a lens depend on?
How curved the lens is
130
What happens to the focal length as the curvature of a lens increases?
The focal length becomes shorter
131
What is a concave lens also known as?
Diverging lens
132
How do parallel rays behave when passing through a concave lens?
They diverge from a point called the principal focus
133
What type of images can lenses produce?
* Real images
* Virtual images
134
Define a real image.
An image formed when light rays converge and can be projected onto a screen
135
What characteristics do real images have?
* Always inverted
* Can be projected onto screens
136
Define a virtual image.
An image formed when light rays do not meet but appear to meet behind the lens
137
What characteristics do virtual images have?
* Always upright
* Cannot be projected onto a screen
138
How is a real image represented in ray diagrams?
By where two solid lines cross
139
How is a virtual image represented in ray diagrams?
By where two dashed lines or one dashed and one solid line cross
140
What occurs when an object is placed further than the focal length from a convex lens?
A real image is formed
141
What occurs when an object is placed closer than the focal length from a convex lens?
A virtual image is formed
142
What type of images do concave lenses produce?
Always virtual images
143
What is the formula for magnification?
Magnification = image height / object height
144
What does a magnification greater than 1 indicate?
The image is magnified
145
What does a magnification equal to 1 indicate?
The object and image are the same size
146
What does a magnification less than 1 indicate?
The image is diminished
147
What is the relationship between wavelength and frequency in the visible light spectrum?
They are inversely proportional
148
Which color has the longest wavelength in the visible spectrum?
Red
149
Which color has the shortest wavelength in the visible spectrum?
Violet
150
Define specular reflection.
Reflection from a smooth surface in a single direction
151
What is an example of specular reflection?
Reflection from a mirror
152
Define diffuse reflection.
Reflection from a rough surface causing scattering
153
What gives objects a dull or matt appearance?
Diffuse reflection
154
What happens to white light when it passes through a prism?
It is separated into its colors
155
What does a color filter do?
Absorbs certain wavelengths and transmits others
156
What color is transmitted through a red filter?
Red light
157
What determines the color of an opaque object?
The wavelengths of light that are more strongly reflected
158
What will an object appear if all wavelengths are reflected equally?
White
159
What will an object appear if all wavelengths are absorbed?
Black
160
What will an object appear if all the light is transmitted?
Transparent
161
What happens when a green surface is exposed to light?
Reflects green light and absorbs all other colours
## Footnote
This explains the color perception of green surfaces.
162
An object will appear white if:
All wavelengths are reflected equally
## Footnote
White color is perceived when no specific wavelength is absorbed.
163
An object will appear black if:
All wavelengths are absorbed
## Footnote
Black color is perceived when no light is reflected.
164
An object will appear transparent if:
All the light is transmitted, and only a small amount is reflected or absorbed
## Footnote
Transparency allows light to pass through without significant interference.
165
What is the key trick to understanding color and color filters?
Think about the behaviour of light and how the eye works
## Footnote
This approach helps avoid confusion in color perception.
166
What does white light contain?
All the colours of the rainbow
## Footnote
White light is a combination of all visible wavelengths.
167
How do most objects interact with wavelengths of white light?
Absorb the majority and reflect a small section
## Footnote
The reflected light is what is detected by our eyes.
168
What does a green leaf do with light?
Absorbs all colours except green, and reflects green light
## Footnote
This is why we perceive the leaf as green.
169
What do filters do to light?
Transmit light of certain wavelengths
## Footnote
Filters selectively allow specific colors to pass while absorbing others.
170
What happens when white light is shone through a blue filter?
Only the blue wavelengths will pass through, the rest will be absorbed
## Footnote
This demonstrates how filters affect color perception.
171
What is refraction?
A type of transmission of light when it reaches the surface of a substance
## Footnote
Refraction changes the direction of light as it passes through different media.
172
What is black body radiation?
The thermal radiation emitted by all bodies (objects)
## Footnote
All objects emit black body radiation in the form of electromagnetic waves, typically in the infrared region.
173
What determines the spectrum of thermal radiation emitted by a body?
The temperature of the body
## Footnote
The intensity and wavelength distribution of emitted waves depend on the body's temperature.
174
What is a perfect black body?
An object that absorbs all radiation incident on it and does not reflect or transmit any radiation
## Footnote
A perfect black body is both a good absorber and emitter of radiation.
175
How does temperature affect the emission of thermal radiation?
As temperature increases, the peak of the black body radiation curve moves to a lower wavelength and a higher intensity
## Footnote
This means hotter objects emit more thermal radiation.
176
At what temperature does an object start emitting a significant amount of red light?
1000 °C
## Footnote
At 6000 °C, an object mainly emits white or blue light.
177
What happens to the temperature of a body when it absorbs radiation faster than it emits?
The temperature increases
## Footnote
Eventually, the body reaches equilibrium when absorption equals emission.
178
What is the role of greenhouse gases in the Earth's atmosphere?
They absorb and reflect back longer-wavelength infrared radiation, preventing it from escaping into space
## Footnote
This process warms the Earth.
179
What is the Greenhouse Effect?
The natural process that warms the Earth's surface from the Sun
## Footnote
It involves absorption and re-radiation of thermal radiation by greenhouse gases.
180
What would happen to the Earth's surface temperature without an atmosphere?
It would drop to about −180 °C at night
## Footnote
This is similar to the Moon’s surface temperature at night.
181
What factors influence the temperature of the Earth?
The rate of light and infrared radiation from the Sun that is:
* Reflected back into space
* Absorbed by the Earth’s atmosphere or surface
* Emitted from the Earth’s surface and atmosphere into space
## Footnote
These factors contribute to the overall thermal balance of the Earth.
182
True or False: A light, shiny outer surface emits more radiation than a dark, matt surface.
False
## Footnote
A light, shiny surface emits less radiation, helping to keep a patient warm under an emergency blanket.
