1
Q
What is a wave?
A
Oscillations or vibrations, about a point. Direction of vibration can differ determining the type of wave.
2
Q
What is a transverse wave?
A
Vibrations are at right angles to the direction, in which the waves transfer energy (perpendicular)
Move spring up and down
3
Q
What is a longitudinal wave?
A
Vibrations are parallel to the direction, in which waves transfer energy
Move spring back and forth
4
Q
What happens for ripples on surface of water and sound waves in air?
A
The water or air doesn’t travel it is the waves
5
Q
Describe what happens when a stone drops into water
A
Ripples are produced, but neither the water, nor the stone move with ripples
6
Q
Describe what happens when someone speaks
A
Voicebox vibrate, producing sound wave that travels through the air, but air doesn’t move
7
Q
What is the top of the wave called?
A
The peak
8
Q
What is the bottom of the wave called?
A
Trough
9
Q
What is the amplitude?
A
Height from equilibrium position to peak or trough
Maximum displacement of a point on the way from its rest position
10
Q
What is the wavelength?
A
Distance from two identical points on wave e.g. Peak to peak or trough to trough.
Distance between a point on one wave and the next point on the same wave
11
Q
What are some examples of transverse wave?
A
Some mechanical waves are transverse e.g. water waves, seismic, S waves
all electromagnetic waves, e.g. ultraviolet, and infrared are transverse
12
Q
What are compressions?
A
Regions of high-pressure particles close together on longitudinal waves
13
Q
What are rarerefractions?
A
Regions of low-pressure particles of far apart on longitudinal waves
14
Q
What are some examples of longitudinal waves?
A
Some mechanical waves longitudinal, e.g. sound, ultrasound, seismic P waves
15
Q
What is a period
A
Time it takes for a wave to complete one cycle
16
Q
What is the equation for wave speed?
A
Wave speed =frequency x wavelength
V = f x lamder
(M/s) (Hz) (m)
(when waves travel from one medium to another)
17
Q
What is frequency?
A
Number of waves, passing a point per second
18
Q
What is the definition of wave speed?
A
Speed at which energy is transferred through a medium/ how fast a wave travels through a medium
19
Q
In the wave speed equation, what always stays the same?
A
Wave speed and wavelength may change, but frequently will always stay the same
20
Q
What is the wave period equation
A
Period = 1/F
(s). (Hz)
21
Q
What is it called when soundwaves get reflected?
A
Waves can get reflected at a boundary between two different materials. Reflected sound with a called echoes
22
Q
What is the law of reflection?
A
Angle of incidence = angle of reflection
(measure these angles from normal-line perpendicular to surface)
23
Q
What happens to a wave at a boundary?
A
A wave at a boundary is either:
Reflected (bounce back from surface)
Absorbed (energy of wave transferred into energy stores within material it travelled into)
Transmitted (continue to move into surface after crossing boundaries)
24
Q
What happens to sound waves in solids and in a vacuum?
A
Sound waves can travel through solids, causing vibrations
Sound waves can’t travel through a vacuum because there are no particles to carry the vibration
25
What happens in the ear? And when does the conversion work?
In the ear sound waves cause the eardrum another part of the ear, to vibrate, which causes the sensation of sound. Conversion only way to solve a limited frequency range.
26
What is the human hearing frequency range?
20 Hz- 20 kHz (20,000 Hz)
High-frequency sounds have higher pitch
High amplitude sounds are louder
27
What is the path of sound once it enters the ear
Soundwaves enter through ear canal. Cause eardrum to vibrate. Three small bones transmit vibrations from eardrum to cochlea. This produces electrical signals which are passed to the brain. These are then interpreted as sound.
28
What is an ultrasound and what is its uses?
Wave with a frequency above the range of human hearing
Uses: image of fetus, cleaning jewellery, breaking down, kidney stones (they are partially reflected at boundaries between two material)
29
How does an ultrasound work?
. Transducer in ultrasound scanner, emits, and detects ultrasound
. Scanner moved across skin.
. Ultrasound waves travel through body and reflected by different boundaries between tissues.
. These reflected weirdo detected by transducer.
. What time it takes for wave to return is recorded
. Distance travelled calculated. (D=SxT)
. Distance is halved to find the depth
. Many of these measurements are taken and computer generates an image.
30
What is produced by earthquakes?
Seismic P and S waves
31
What does the curved path of seismic waves show us
That the density of the earths mantle is gradually changing
32
What can’t S waves do
S waves can’t travel through liquids. Not detected on the opposite side of us to earthquake ~liquid core to the earth
33
What are the properties of P waves
Longitudinal
Faster
Travel through solids and liquids
34
What are the properties of S waves?
Transverse
Slower
Travel through solids only
35
What are shadow zones?
Area where no P-waves are detected-tells us solid inner core (refracted)
36
How does a echo sounding work?
Sonar uses ultrasound, detect objects underwater
Ultrasound is emitted
Waves reflect from the bottom of the bed or object to being detected
Time taken for wave to return recorded
Distance = wave speed x time
Distance is halved to find the depth
37
How to set up the ripple tank required practical
Ripple tank used to observe features of water waves- shallow tray of water
In water vibrating bar connected to power pack . Vibrate which creates waves across the water.
Above the ripple tank, there is a lamp below the report and there was a sheet of paper.-when light shines through the water creates an image of waves on the paper
38
How could you do the mobile phone in the ripple tank required practical
Record with using mobile phone and playback recording at different speeds or freeze image completely
39
How to workout the wavelength in the ripple tank practical
Place meter, ruler on paper and freeze image. Measure the length of 10 wavelengths and divide by 10 to work out the length of one wavelength
40
How to measure the frequency in the ripple tank, practical
Please timer next to paper and count the number of waves, passing a point in one second -(count number of waves in 10 seconds then / 10) ( record and watch in slow motion)
41
How can we work out the wave speed in the ripple tank, practical
Speed = frequency x wavelength
OR
Select a wave and measure the time it takes to move the length of the tank
S = D/t
42
Why would you obtain slightly different results using the 2 different methods for measuring wave speed
Due to measurement errors e.g. timing?
43
What are electromagnetic waves?
Transverse waves transfer energy before my continuous spectrum
44
What is common about all electromagnetic waves?
All electromagnetic waves travel at the same velocity through a vacuum in air
45
What are the different types of electromagnetic wave?
Radiowave, microwave, infrared, visible light, ultraviolet, x-ray, gamma ray
(Longest wavelength,lowest frequency,lowest energy) to (shortest wavelength,highest frequency,highest energy
rabbit meet in very ultra xpensive gardens
46
What my different substances are electromagnetic wave
Different substances may absorb transmit, refract, or reflect electromagnetic waves in ways that vary with their wavelength
47
What happens if an electromagnetic wave changes velocity when moving from one substance to another
If the electromagnetic wave changes velocity when moving from one substance to another, it will be refracted changing its direction. this can be shown by ray diagrams. (angle of incidence and angle of reflection always measured from normal not surface.)
48
What are wavefront diagrams used for
Wavefront diagrams can be used to explain refraction in terms of the changes of speed that occurs when a wave travels from one medium to another. Wave fronts are imaginary lines perpendicular to the direction, the wave is travelling.
49
What happens if a wave slows down when crossing a boundary
If a wave slows down when crossing around with the wave fronts become closer together
50
What happens if a wave crosses with crosses the boundary at angle
If a wave crosses the boundary at an angle, one end of the wave front will change speed before the other, changing the waves direction
51
How can radio waves be produced?
Radio waves can be produced by oscillations in electrical circuits. When radio waves get absorbed, they can create an alternating current with the same frequency as radio waves.
52
How can electromagnetic waves be generated or absorbed by atoms?
Electromagnetic waves can be generated or absorb because of changes an atoms and the nuclei of atoms. When the electrons in an atom move down energy levels, they will emit electromagnetic waves.
53
What does the affect of electromagnetic waves depend on?
. Type of radiation
. The size of radiation dose.
54
What is radiation dose?
A measure of the risk of harm, resulting from an exposure of the body to the radiation. Measured in sieverts
55
What does 1000 millisieverts equal to
1000mSv=1Sv
56
Which electromagnetic waves are more hazardous than others
Ultraviolet waves, x-rays and gamma rays can have hazardous effects on human body tissue
57
What happens when the frequency of electromagnetic wave increases?
Electromagnetic waves become more dangerous as the frequency of the wave increases
58
What are the harmful effects of microwaves?
Internal heating of body cells
59
What are the harmful effects of infrared?
Skin burns
60
What are the harmful effects of ultraviolet?
Damage to surface cells leading to skin cancer
Damage to eyes leading to eye conditions
61
What are the harmful effects of x-rays?
Mutations and damage to body cells
62
What are the harmful effects of gamma rays?
Mutation and damage to body cells
63
What are radio waves used for and why?
Broadcasting, satellite, transmissions and communications
Can travel long distances in air. longer wavelength can bend around objects, allowing them to be detected
64
What can microwave be used for and why?
Cooking, satellite, transmissions communications.
Able to pass through the earths atmosphere to reach satellite
65
What can infrared be used for and why?
Cooking, thermal imaging, short range communications
Able to be transferred quickly to heat, rooms and food
66
What can visible light be used for and why?
Vision ,photography
Short wavelength, able to carry more information
67
What can ultraviolet be used for and why?
Security markings, fluorescent lamps, disinfecting water
Has more energy than visible light . Some chemicals used in fluorescent light bulbs can absorb the UV light and emit visible light.
68
What can x-rays be used for and why?
Observing the internal structure of objects, medical x-rays and airport security scanners.
Can pass easily through skin and flesh, but not denser materials Like bone
69
What can gamma rays be used for and why?
Sterilising, food and medical equipment. Treating and detecting cancer.
Very high energy so can kill cancer and bacteria
70
What is magnification?
Magnification of the ratio between the image, height and the object height. Has no units.
71
What is the equation for magnification?
Magnificatio= image height/object height
(Heights can be measured in cm or mm-both should be measured using same units)
72
What are the colours of the visible light spectrum and what do they have?
ROYGBIV
all colours of visible, light spectrum have their own narrow band of wavelength and frequency
73
What are the two different types of reflection?
Specular reflection-reflection, from a smooth surface in a single direction
diffuse reflection-reflection from a rough surface
74
What do you transparent, translucent and opaque objects do?
Transparent objects-transmit visible light
Translucent objects -transmit visible light, but the light rays are scattered and reflected
Opaque object-do not transmit, visible light, but they absorb and reflect it
75
What is the colour of an opaque object, determined by
The colour of an opaque object is determined by which wavelength of light or more strongly reflected
any wavelength, which don’t get reflected are absorbed
76
Why would an object be white
All wavelength of light are reflected equally
77
Why would an object to be Red
Red light is reflected and all other wavelengths are absorbed
78
Why would an object be black?
All wavelengths are absorbed
79
How do you colour filters work?
If white light is passed through a coloured filter, all the colours will be absorbed by the filter except light that is the same colour as the filter
E.g. red filter will transmit red light only absorb OYGBIV
80
What does the intensity and wavelength of light emitted depend on?
The intensity and wavelength of light that are emitted depends on the temperature of the body
81
What is a perfect black body
An object absorbs all the radiation incident on it, and does not reflect or transmit any radiation. A perfect emitter.
Body=object
82
What do all bodies do?
All bodies, emit, or absorb infrared radiation
Shiny, silver and white surfaces are the worst absorbers. This is because they reflect all visible, light wavelength.
Poor absorbers are also poor emitters
Good, absorbers are also good emitters
83
What did bodies at a constant temperature do
Bodies at a constant temperature absorb radiation at the same rate they emit it
84
What does it mean if the temperature of a body increases?
Read the temperature of the body increase of this is because the body absorb radiation faster than it emits it. Hotter objects, emit, more infrared radiation in a given time.
85
What does the earths temperature depend on?
. Rate of absorption of radiation.
. Rate of emission of radiation.
. The reflection of radiation into space
86
How to set up the practical to measure, wavelength, frequency, and speed of a wave in solid
. String with one and attach to a vibration generator other and hanging mass. (keep string taut)
. Vibration generated connected to signal generator.-allows us to change frequency of vibration of spring
. When you turn on power, the string vibrates.
87
What is a standing wave
At a certain frequency. Standing waves created due to the effect called resonance, find this in stringed musical instruments, like guitars.
88
Describe the method for the practical of waves in a solid
To measure wavelength of standing wave
1. Set up equipment as previously stated.
2. Use a ruler the total length of the wave from the wooden bridge to vibration generator.
3. Read frequently from signal generator.
4. Used to calculate speed. V=f x wavelength
Change frequency -wave changes to 3 half wavelength
89
How to calculate wavelength of half wavelengths
Wavelength = (total length / number of half wavelength) x2
90
How do you investigate reflection of light by different surfaces and refraction of light by different substances?
1. Get a piece of a3 paper and draw a straight line down the centre using a ruler.
2. Draw another line at a right angle using a protractor. (Normal)
3. Place glass box so normal near centre
4.draw around block- turn off light
5. Direct Ray box (w lens and slit) so ray of light hit block at normal (incident ray)
6.angle between normal and ray= angle of incidence
7. Adjust ray box to change AOI-at certain angle rayreflected back and another ray leaves block opposite side (transmitted ray)
8.mark path of all rays. Remove black and draw on rays- draw transmitted ray path thru glass and measure angles
9.angle of refraction- between normal and TR path
10.repeat using different material blocks eg perspex
91
What will you notice about the angle of incidence and angle of reflection and the angle of refraction for glass and perspex
. Angle of incidence and angle of reflection will be the same for glass and perspex because they don’t depend on the material.
. Angle of refraction will be different
92
How to investigate how much infrared radiation is radiated by different surfaces
1. Filll Leslie cube with hot water
2. Point infrared detector at each surface and record amount emitted (same distance every time, so it is repeatable)
3.most- matt black, shiny black, white, shiny metallic least
Can use thermometer with bulb painted black instead of infrared detector . However, less resolution
93
What is the Leslie cube?
Hot objects, emit infrared radiation-not visible by human eye
Leslie Cube measures how much infrared is emitted from different surfaces. Has four different surfaces, shiny metallic white, shiny black matte black
94
What is resolution?
Smallest change that can be detected
95
How to investigate how much infrared radiation is absorbed by different surfaces
1. Please the infrared heater between two metal plates.
2. One plate is painted shiny metallic, and the other is Matt black
3. Use Vasoline to attach pin on each side.
4. Turn on the heater and start a timer.
5. The temperature of the pay increases of infrared is absorbed.
6. Record time for Vasoline to melt and pins to fall.
Matt black absorbs more -pin falls frst
Infrared tends to be reflected from shiny metallic surfaces instead
