Waves Flashcards
1
Q
What are the two types of waves? (W Ph)
A
Transverse and Longitudinal
2
Q
What do waves do in terms of transfer? (W Ph)
A
They transfer energy from one place to the other.
3
Q
Which part travels? (W Ph)
A
- It is the wave that travels not the medium (air, water, solid)
- The slinky experiment. The slinky oscillates up and down or side to side but the actual coils don’t move. So the waves don’t permanently move the particles but they do vibrate temporarily.
4
Q
What is the movement of oscillation in comparison to the direction of energy transfer for a transverse wave? (W Ph)
A
The oscillations are perpendicular to the direction of energy transfer.
5
Q
How do the oscillations move in a transverse waves? (W Ph)
A
Up and down
6
Q
What is the direction of energy transfer in transverse waves? (W Ph)
A
Sideways
7
Q
What is the movement of oscillation in comparison to the direction of energy transfer for a longitudinal wave? (W Ph)
A
The oscillations are parallel to the direction of energy transfer.
8
Q
What is the direction of energy transfer in longitudinal waves? (W Ph)
A
Sideways
9
Q
How do the oscillations move in a longitudinal waves? (W Ph)
A
Side to side
10
Q
What is an example of transverse waves and what type of force does it carry? (W Ph)
A
Ripples on the surface of the water + kinetic energy
11
Q
What is an example of a longitudinal wave and what type of force does it carry? (W Ph)
A
Sound waves travelling in air + sound energy.
12
Q
What do longitudinal waves require? (W Ph)
A
A medium to travel in (air, liquid, solid)
13
Q
What are the regions called in a longitudinal wave where the air particles are very close together? (W Ph)
A
Compressions
14
Q
What are the regions called in a longitudinal wave where the air particles are far away together? (W Ph)
A
Rarefractions
15
Q
What can waves do at the boundary between two different materials? (RoW W Ph)
A
They can be reflected. E.g sound wave reflections cause echoes
16
Q
What does the law of reflection state? (RoW W Ph)
A
Angle of incidence = angle of reflection
17
Q
What an example of the law of reflection? (RoW W Ph)
A
If a light ray hits at 32 degrees then it will be reflected at 32 degrees
18
Q
Where are the angles of incidence and reflection measured between? (RoW W Ph)
A
The light ray and the normal
19
Q
What is the normal? (RoW W Ph)
A
An imaginary line at 90 degrees to the surface.
20
Q
What is the incident ray? (RoW W Ph)
A
The ray going towards a surface. Aka a light/ sound ray hitting a mirror.
21
Q
What is the reflected ray? (RoW W Ph)
A
The ray that bounces off of a surface.
22
Q
What is a specular reflection? (RoW W Ph)
A
Reflection from a smooth, flat surface.
23
Q
What is the image in a mirror both? (RoW W Ph)
A
- upright
- virtual
24
Q
What is a virtual image? (RoW W Ph)
A
An image from which rays of light appear to come but do not do so in reality.
25
What is Diffuse reflection? (RoW W Ph)
When a surface is rough, diffuse reflection happens. Instead of forming an image, the reflected light is scattered in all directions. It may cause a distorted image of an object, as occurs in rippleing water or no image. Each individual reflection still obeys the law.
26
What is rafraction? (ReoW W Ph)
The process by which a wave changes speed and sometimes direction upon entering a denser or less dense medium. E.g light ray changes direction when refracted by a lens
27
How does rafraction cause optical illusions? (ReoW W Ph)
The light waves appear to come from a different position to their actual source
28
What does the density mean for the speed of a wave transmitting through it? (ReoW W Ph)
In general the denser the transparent material the more slowly light travels through it.
29
What happens when a light ray travels from a less dense material to a more dense material? (ReoW W Ph)
The light ray slows down. If the ray meets the boundary at an angle to the normal, it bends towards the normal.
30
What is the acronym for remembering how the ray changes going through materials of different denseness. (ReoW W Ph)
FAST
if it gets faster - away from the normal (dense to less dense)
if it gets Slower - towards the normal (dense to more dense)
31
What is frequency in terms of waves? (ReoW W Ph)
The number of waves produced each second. The unit of frequency is hertz
32
What is the relationship between wavelength and wave speed for a given frequency of light? (ReoW W Ph)
Wavelength is proportional to the wave speed
33
Equation for wave speed (ReoW W Ph)
= frequency x wavelength
34
What is the maximum deapth of the earths crust? Is this thick or thin? (SW W Ph)
50km and this is very thin
35
Is the crust a solid? (SW W Ph)
yes
36
Is the mantle a solid? (SW W Ph)
yes
37
Is the outer core a solid? (SW W Ph)
No, it is a liquid
38
Is the inner core a solid? (SW W Ph)
yes it is.
39
Can scientists directly observe the interior of the earth, if so how? (SW W Ph)
No, even the deapest mines only go a few kilometers into the crust.
40
How do scientists know that the earth has this structure? (SW W Ph)
becuase of earthquakes and their seismic waves
41
What are seismic waves? (SW W Ph)
they come from earthquakes and they carry the energy away from the earthquake through the earth
42
How do scientists find seismic waves? (SW W Ph)
they can be detected by seismometers in different courties.
43
What are the two main types of seismic waves? (SW W Ph)
P waves and S waves
44
Information about P waves? (SW W Ph)
- longitudinal
- pass through solids and liquids
- travel faster than S waves
45
Information about S waves? (SW W Ph)
- transverse (remeber this becuase transverse contains the letter s)
- only travel through solids
46
How do S waves travel through the earth and why? (SW W Ph)
travel in curved paths due to the density changes in the earth.
47
What is the place called where no s waves can be detected during an earthquake and why is that the case? (SW W Ph)
the S-wave shadow zone
They can't be detected there because s waves can't pass through liquids
48
How did scientists tell that the earth must have a liquid core? (SW W Ph)
becuase the s waves could not be detected in their shadow zone and since they can't pass through liquids, it must have a liquid there.
49
What are the places called where P waves cannot be detected and why cant they be detected there? (SW W Ph)
P-wave shadow zones
They can't be detected in these parts becuase P waves travel faster in solids that in liquids. This means that the P waves slow down when the enter the liquid outer core which causes them to refract. They also refract when they leave the outer core. This confirmes that the outer core is a liquid
50
What happens when electromagnetic waves are generated or absorbed? (POW2 W Ph)
changes take place in atoms or in the nuclei of atoms.
51
What is a way that a change takes place in an atom to form an electromagnetic wave? (POW2 W Ph)
When we heat atoms, we cause electrons to move from one energy level to a higher one. When this electron returns to its original energy level, it generates an electromagnetic wave (light)
52
What is a way that a change takes place in an atom's nucleous to form an electromagnetic wave? (POW2 W Ph)
Gamma Rays. Gamma rays can be emitted from the nucleus of radioactive atoms. Once this gamma ray has been emitted, the nucleus has less energy than it had at the start.
53
What are the waves that are potentially very hazardous to the human body? (POW2 W Ph)
Ultraviolet
X rays
Gamma Rays
54
What harm can ultra violet waves cause to humans? (POW2 W Ph)
increase the risk of skin cancer
cause the skin to age prematurely
55
What types of waves are X rays and gamma rays? (POW2 W Ph)
ionising (knock electrons off atoms when they are absorbed )
56
What are the potential harm coming from X rays and Gamma Rays? (POW2 W Ph)
since they are ionising (knock off atoms when they are absorbed) they can cause a mutation of genes and this increases the risk of cancer
57
What does the amount of damage caused by radiation depend on? (POW2 W Ph)
the type of radiation and the dose.
58
What is the dose of raditaion measured in? (POW2 W Ph)
sieverts (Sv) or millisieverts (mSv)
59
How can radiowaves be produced and what is an example of something they be absorbed by? (POW2 W Ph)
when electrons oscillate in electrical circuits.
they can be absorbed by an electrical circuit in an aerial which can cause electrons in that circuit to oscillate which can create an alternating current with the same frequency as the radio waves.
60
What is an example of an electromagnetic wave? (EM W Ph)
Light
61
What are electromagnetic waves and what are some good examples of objects that do this? (EM W Ph)
They are transverse waves and transfer energy from the source of the waves to an absorber. An example of this is a microwave, they transfer energy from the oven (source) to the food (absorber). Another example is when light waves transfer energy from the Sub (source) to solar panels on a spacecraft (absorber)
62
What happens when we pass white light through a prism? (EM W Ph)
it splits into a spectrum. Each of these colours have a different wavelength and frequency.
63
What is the order in which the colours of an electrogmagnetic wave's spectrum go from having the lowest frequency to the highest frequency? (EM W Ph)
Red Orange Yellow Green Blue Indigo Violet
64
What are the colours in a electromagnetic spectrum? (EM W Ph)
Red
Orange
Yellow
Green
Blue
Indigo
Violet
65
What is the order in which the colours of an electrogmagnetic wave's spectrum go from having the longer wavelength to the shorter wavelength? (EM W Ph)
Red Orange Yellow Green Blue Indigo Violet
66
What are the parts of the electromagnetic spectrum that we can see? (EM W Ph)
Visible light is the only part of the electromagnetic spectrum that can be detected by the human eye
67
What phrase helps to remember the electromagnetic spectrum
Raw Meat Is Very Unsanitary eXcept Giraffe
Radio - Microwave - Infrared - Visible Light - Ultra violet - X rays - Gamma rays
68
What does the frequency and wavelength do from Radio to Gamma Ray? (EM W Ph)
Frequency goes from low to high
Wavelength goes from long to short
69
What does a ‘continuous spectrum’ mean and what is an example? (EM W Ph)
Meaning: the cut off between one type of wave and another is not always clear
Example: Electromagnetic spectrum
70
Do electromagnetic waves need to travel in a medium and what does that mean? (EM W Ph)
Electromagnetic waves do not need a medium to travel in which means that they can travel through a vacuum e.g space
71
What is the speed that electromagnetic waves travel through a vacuum? (EM W Ph)
All of them travel at 300000000m/s (8 zeros)
72
What are microwaves absorbed and reflected by? (EM W Ph)
Absorbed
~ absorbed by foods which contain water molecules
Reflected
~ reflected from metals
73
What are light waves absorbed and reflected by? (EM W Ph)
Absorbed
~ absorbed by black surfaces
Reflected
~ reflected from shiny, metallic surfaces
74
Radio waves
- transmit radio and terrestrial TV signals
- travel long distances before they are absorbed, longer wavelengths can also spread out between hills
- they reflect off of a layer of charged particles in atmosphere which allows us to send radio waves very long distances around the earth
75
Microwaves
- used for heating food because most food contains a lot of water molecules which absorb the energy which increases the temperature of the food
- used to communicate with satellites in space because they can pass through the earth’s atmosphere without being reflected or refracted
76
Infrared
- emitted by electrical heaters and is also used to cook food in ovens because the energy of infrared is easily absorbed by the surfaces of objects
- also used in infrared cameras e.g check buildings for heat losses
77
Visible Light
- communication using fibre optics (very thin strands of glass which we can transmit pulses of light down and use these pulses to carry information (telephone and cable tv signals)
- short wavelength so can carry lots of information
78
Ultra violet
- energy efficient light bulbs. Ultra violet light is created inside the bulb as it has a short wavelength, it carries more energy than the visible light. Ultra violet light is absorbed by internal surface of the bulb and it is converted to visible light. Requires much less energy
- sun tanning but it can increase the risk of skin cancer and causes premature skin aging
79
X rays and Gamma Rays
- medical imaging X-ray to visualise broken bones Gamma to detect cancer
- very penetrative / pass easily through body tissue but X-ray is absorbed by bone
- used in medical treatments e.g treat cancer
