Topic 6 Flashcards
(87 cards)
1
Q
What are the two types of categories waves come under?
A
Transverse and Longitudinal
2
Q
What are Oscillations?
A
A regular movement either side to side or up and down or vibrations.
3
Q
What is a Transverse wave?
A
When the oscillations are perpendicular to the direction of energy transfer.
4
Q
Name 5 examples of Transverse waves
A
Light Xrays Infrared S waves Water waves
5
Q
What is a wavelength?
A
It is the difference between two troughs
6
Q
What is the amplitude of a wave?
A
The amplitude of a wave is the distance from the still position to the bottom of a trough.
7
Q
What is the frequency of a wave?
A
Total amount of waves per second.
8
Q
What is the Period of a wave?
A
It is the time in seconds for one wave to pass a point.
9
Q
What is the equation with units for the Period of a wave?
A
Period(s) = 1 / Frequency (Hz)
10
Q
What is a Longitudinal wave?
A
The oscillations of the wave are parallel to the direction of energy transfer
11
Q
Name 2 examples of Longitudinal waves?
A
Sound P waves (Earthquakes)
12
Q
What does Rarefraction mean?
A
Where the particles are very spaced out.
13
Q
What does Compression mean?
A
Where the particles are close together.
14
Q
How do you work out the wave length of a Longitudinal wave?
A
It is the difference between two compression’s or two rarefraction.
15
Q
What does oscillations are parallel to the direction of energy transfer in Longitudinal wave mean?
A
Vibrations are back and forwards in line with the direction of energy transfer
16
Q
What do Sound waves cause Particles to do?
A
Vibrate
17
Q
What is Wave speed?
A
Is the speed the wave is moving at.
18
Q
What is the wave speed equation?
A
Wave speed (m/s) = Frequency(Hz) * Wavelength(m)
19
Q
Why do scientists use an Oscilloscope to see frequency and Amplitude of a Longitudinal wave?
A
Because it is hard to see the frequency and Amplitude.
20
Q
What does a Oscilloscope do?
A
This takes the sound and display the sound wave on the screen.
21
Q
What wave does a Oscilloscope display with a Sound wave?
A
A transverse wave of sound as it easier to work out amplitude and frequency. THEY ARE NOT TRANSVERSE WAVES THOUGH.
22
Q
On a Oscilloscope what does high frequency wave mean?
A
High pitch sound
23
Q
On a Oscilloscope what does a low frequency wave mean?
A
Low pitch sound
24
Q
On a Oscilloscope what does a Small amplitude wave mean?
A
Quiet sound
25
On a Oscilloscope what does a Large amplitude wave mean?
Loud sound
26
What do Sound waves require to produce a sound?
A medium e.g Air
27
Why can sound not pass through a Vacuum?
No particles.
28
What is the speed of sound in air?
330 m/s
29
What is an echo?
When sound waves reflect off surfaces
30
How do you measure the speed of Water ripples?
1) Using a signal generator connected to a dipper of a ripple tank you can create water waves
2) Use strobe light to see wave crests on a screen below the tank
3) Measure the total wavelength's by counting how many troughs there are in the distance in time given.
4) Divide the amount of wavelengths by the distance of them wave lengths to find wavelength of the wave
5) Find frequency by dividing the number of waves by the time taken
6) use wave speed equation to find speed of wave.
31
Describe the way you would find Wave speed of a string?
1) Get a sting with one end connected to a vibration generator and the other end of the string connected to a hanging mass keeping the string tight
2) The vibration generator is connected to a signal generator, which allows us to change frequency of the vibration of spring.
3) When we turn on the signal generator the spring vibrates, At a certain frequency you get a wave standing wave ( usually found in guitars0
4) measure wave length of standing wave using ruler, the total wavelength from wooden bridge to the vibration generator
5) the signal generator tells you frequency and use wave speed equation to find wave speed.
32
When waves meet a boundary what are the 3 things that can happen?
Reflect
Transmit
Absorb
33
What does Absorbed mean when a wave meets a boundary?
The wave is absorbed by second material, the wave transfers energy to the material's energy stores e.g thermal energy store leads to Heating.
34
What does Transmitted mean when a wave meets a boundary ?
The waves carry on travelling through the new material, often leading to Refraction.
35
What does Reflection mean when a wave meets a boundary?
This is where the incoming ray is neither absorbed or transmitted but instead sent back away from the second material.
36
What are Electromagnetic waves?
Transverse ways which transfer energy from a source to an absorber.
37
What is the mnemonic to remember the electromagnetic spectrum?
Raw meat is very unsanitary eXecpt Giraffe
38
What is the actual electromagnetic spectrum?
Radio waves, Micro waves, Infrared waves, Visible light, Ultraviolet waves, Xrays and Gamma rays.
39
What can our eyes detect from the spectrum?
Visible light
40
At the start of the Electromagnetic spectrum what does what are the frequency and wavelength?
At the start they have a low frequency and a long wavelength
41
At the end of the Electromagnetic spectrum what does what are the frequency and wavelength?
High frequency shorter wave length
42
Do the Electromagnetic waves need a medium to pass through?
No they can pass through space, they travel at the same distance about 3 X 10 to the power of 8
43
In the electromagnetic spectrum what increases?
The frequency increases from Radio waves to Gamma rays
44
In the electromagnetic spectrum what decreases?
The wave length decreases from Radio waves to Gamma rays
45
What is Refraction?
When waves can change direction when they change speed moving from one medium to another.
46
Explain how a Ray diagram shows a light wave passing through air into glass using Refraction?
When light passes from air into glass, the light waves slow down, causing the direction of the wave to change bending towards the normal line
47
Explain how a Ray diagram shows a light wave passing through glass into the air using Refraction?
When the light waves passes from the glass back to the air the light wave speeds up bending away from the normal line,
48
What is a wave front?
It is an imaginary line that connects all the same points in a wave.
49
Why in a Wave front diagram can waves change direction when they pass air to the glass?
When the first wave front start to move into the glass, those parts of the wave front slow down, causing those parts of the wave front to get closer together, this means the wavelength gets smaller causing the direction to change direction towards normal line, the ways refract.
50
What happens when the wave front goes across the normal line when passing in air through the glass?
The wave slows down as they pass through the glass, causing the wave front to slow down at the same time, meaning the wave doesn't change direction
51
What are Radio waves used for?
To transmit radios and terrestrial TV
52
How are Radio waves produced?
It can be produced by alternating currents
53
How do Radio waves travel around the world?
There is a layer of charged particles in the atmosphere called the ionisphere which the radio waves reflect off it.
54
What can Microwaves be used for?
satellite communication
cooking food
Mobile phone networks
55
why can microwaves be used to communicate with satellite in space?
this is because microwaves can pass through the Earth's atmosphere without being reflected or refracted.
56
How is Mobile phones used for Communication?
They transmit and receive microwaves.
57
How are Microwaves used to heat food?
Most foods contain water molecules and water molecules absorb the energy of microwaves causing the temperature to increase
58
What can Infrared Radiation be used for?
Infrared Cameras
| Cook food in ovens
59
How is Infrared radiation used to cook foods?
The temperature of the food increases when it absorbs IR radiation
60
Name 2 uses of Visible light?
Communication using optic fibres
| 2) carry telephone and cable tv signals this is because it has a short wavelength so can carry lots of information
61
What are optical fibres
Thin glass fibres
62
How do Optical fibres work?
By reflection, they light rays bounce back and fourth until they reach end of the fibre.
63
Name uses of Ultraviolet radiation
Flourescence
| Suntan
64
How does Flourescence work?
In a bulb It can absorb ultraviolet radiation which emit light and converts into visible light (They are long lasting energy efficient)
65
How do Sunbed's work in suntanning?
UV radiation is used as an artificial sunlight
66
What are Gamma rays used for?
```
Radiotherapy
Medical imaging (to detect cancer)
```
67
How does Gamma rays work through Radio therapy?
Gamma is injected in body and the gamma rays pass out the body.
68
What are X-rays uses?
Medical imaging
| Medical treatment e.g to kill tumours
69
Explain why plastic optical fibres use pulses of visible light to transfer data?
Visible light is not easily absorbed or scattered in a fibre.
70
Describe method used to the emission of Leslie cube?
1) Place a empty Leslie cube on a heat proof mat
2) Poor boiled kettle water in the Leslie cube
3) use thermometer and touch each vertical side of the Leslie cube (all temp should be the same)
4) Use infrared detector a set distance away from cube vertical faces and record IR radiation it detects for each face
5) You find that the Matt black detects the most Infrared Radiation
71
Why was does Black clothes make you hotter?
Because they are good absorbers and emitters of Infrared radiation
72
How do you investigate amount of Infrared radiation absorbed by different materials?
1) Have a Bunsen burner and on either side have two metal plates
2) One plate is Matt black and one is sliver
3) Stick ball bearings on each side of the different plate with solid pieces of candle wax
3) The ball bearing that drops first is the Matt black one
73
Why does the bull bearing on the Matt black plate drop first?
The black surface absorbs more infrared radiation, transferring more energy to the thermal energy store of the wax.
74
A student makes two identical cups of tea in two mugs - the mugs are the same, apart from the colour - one is black and one is white. Explain which cup of tea will initially cool at a faster rate.
The black mug will initially cool at a faster rate, this is because a black surface emits more infrared radiation than a white one, so more energy is transferred away from the thermal energy store of the tea.
75
If low frequency waves don't transfer much energy what does it mean?
It can pass through soft tissue without being absorbed
76
If high frequency waves transfer lots of energy what does it mean?
They can cause a lot of energy
77
What are X-rays and Gamma rays examples of?
Ionizing radiation
78
What is Ionizing radiation?
Carry enough energy to knock off of atoms
79
What is Radiation dose?
The risk of harm from the body being exposed to radiation
80
What is Radiation dose measured in?
mSv = Siverts
81
Give two effects of being exposed to radiation
Gene mutation
| Cancer
82
A patient's pelvis is being examined. It can either be examined with a single X-ray photograph or with a CT scan. An X-ray of the pelvis has a radiation dose of 0.7mSv. A ct scan of the pelvis has a radiation dose of 7mSv. How much larger added risk of harm if the patient has a CT scan?
10 Times added risk of harm from a CT scan from a X-ray
83
What is the unit of dose?
Sievert (Sv)
84
Why do we use mSv instead of Sv?
Because it is large and life threating so we use mSv which 1000mSv = 1Sv.
85
What is the speed of sound in the air?
330m/s
86
How can you find measure the speed of sound waves in air?
1) two people are separated by certain amount of meters
2) Person A is holding a pair of symbols
3) Person B is holding a timer
4) Person B starts timing when she sees person A clash the symbols together.
5) Person B stops timing when she hears the sound of the symbols clashing.
6) We can then calculate speed of the sound waves by dividing the distance traveled by time taken
87
What is the problems with the experiment of finding the speed of sound waves in air?
1) Every one has a different reaction time
2) The time taken between seeing the symbols clash and hearing the sound is very short indeed meaning it is very difficult to press the timer at the correct times.
