Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

On the wild side > Light and Waves > Flashcards

Light and Waves Flashcards

1
Q

What are waves?

A

a means of transferring energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What doesn’t happen with waves?

A

There is no transfer of matter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are transverse waves?

A

Waves where the direction of energy transfer is perpendicular to the direction of oscillations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are longitudinal waves?

A

Waves where the direction of energy transfer is along the direction of oscillations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is an example of a transverse wave?

A

light, waves travelling on the surface of water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is an example of a longitudinal wave?

A

sound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is amplitude?

A

the maximum movement of particles from their resting position caused by a wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens when waves strike a concave barrier?

A

They become curved and are made to converge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens when waves strike a convex barrier?

A

They are made to diverge and spread out.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens when waves enter a shallower region?

A

their wavelength becomes shorter and because the frequency is constant the velocity also decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens when the waves enter the deeper region?

A

their wavelength increase and so does the velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is necessary for refraction to occur?

A

the boundary between the shallow water and the deep water is at an angle to the direction in which the waves are moving

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens when waves enter shallow vs deep region?

A

Shallow: bend towards normal and slow down

Deep: bend away form the normal and speed up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the common features to all electromagnetic waves?

A

they are all transverse

they all travel at 3x108 m/s

they can all be diffracted, refracted and reflected

they all transfer energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the wave with the longest wavelength?

A

radio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Which wave has the most penetrating power?

A

gamma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Which is the most high frequency wave?

A

gamma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are radio waves used for?

A

broadcasting and communication

reflect of ionosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How are radio waves produced?

A

They are emitted by a transmitter, cross an aerial and the information is receives as they are detected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What detects radio waves?

A

TV aerials and radio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the uses of microwaves?

A

cooking, radar and satellite transmissions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How do microwaves heat food?

A

The waves cause water to vibrate more and increase there amplitude. This increase in kinetic energy is essentially an increase in temperature and so the water molecules become very hot.

The food is cooked throughout not just on the outside

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the dangers of microwaves?

A

They can heat human tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How are the dangers of microwaves reduced?

A

Microwaves have metal screens that reflect them and keep them inside the oven.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
How are microwaves used for communication?
The waves pass through the Earth's atmosphere and are used to carry signals to orbiting satellites. They also carry messages sent from phones so therefore can pass through solids (glass/brick)
26
What do all objects do?
emit IR
27
What makes more IR be emitted?
If something is hotter
28
What detects IR?
skin, blackened thermometers, IR cameras
29
What are the uses of IR?
night vision equipment, remote controls for TV, stereo and videos cooking in grills and toasters optical fibres
30
Why are IR used for remotes?
They have a low penetrating power and so are unlikely to interact with other signals.
31
What are the dangers of IR?
skin burning and if cells absorb too much they are killed/damaged
32
What emits visible light and detects it?
luminous objects detected by the eye, cameras, LDRs and photographic film
33
What are the uses of Visible light?
seeing light from lasers is used to read compact discs and barcodes optical fibres: communication and seeing inside the body
34
Which colour has the longest wavelength?
red light
35
What is the frequency of red light like?
low frequency
36
What are the dangers of UV light?
blindness - harmful to eyes skin cancer - damage to skin
37
How does UV light cause cancer?
causes cancer by ionizing cells under skin surface
38
What is UV light used in?
UV tanning lamps some chemicals fluoresce when exposed to UV light
39
What is helping to reduce UV light?
ozone absorbs it
40
What does fluorescence mean?
an object that absorbs UV light and emits visible light
41
What emits X-rays?
X-ray tubes
42
What detects X-rays?
photographic film
43
What are X-rays used for?
in radiography to observe internal objects of the body security checks in airports in the industry to check the internal structures of objects for cracks etc
44
What are the dangers of X-rays?
excessive exposure can cause cancer
45
How can you protect against X rays?
stand behind a lead screen protective clothing
46
What are gamma rays emitted by?
radioactive material
47
What are gamma rays detected by?
Geiger- Muller tube
48
What are the uses of gamma rays?
sterilise medical equipment kill micro-organisms so food keeps for longer radiotherapy
49
What are the dangers of Gamma?
They have a high penetrating power causing mutations in genes that can lead to cancer. A small dose can cause cells to become cancerous and a large dose can kill cancer cells.
50
What are the benefits of analogue signals?
when the signal is amplified so too is the noise which weakens the clarity of the signal if signals have a similar frequency they interfere with each other and it is difficult to distinguish each signal Quantisation (when a continuous range is rounded) can give rise to a loss of lots of INFO wider range of frequencies are needed to broadcast an analogue signal
51
What are the benefits of digital signals?
regeneration of signal is clear and exact as noise is ignored easily Many signals can be transmitted at once with one cable Quantisation doesn't lose any information so more info can be transmitter in smaller space without any COMPROMISE on the quality of the signal More programmes can be broadcast over the same frequencies Digital systems are easier to design and build Digital systems deal with easy to process data Can be handled by microprocessors Wider bandwidth so the response is clearer yet the noise is lower Carries more info than analogue because the generator can switch between two values quickly in short space of time compared to analogue where the values are so wide ranging it takes longer to generate
52
Why can digital signals carry more info?
They can also squeeze in more programmes, because digital signals can carry more information per second than analogue signals. When quantisation occurs less info is lost therefore more info is carried. Also they have a large bandwidth.
53
What is an analogue signal?
Analogue signals can vary in frequency, amplitude or both continuously.
54
What are digital signals?
Digital signals are a series of pulses consisting of just two states, ON (1) or OFF (0). There are no values in between.
55
Explain the meaning of the critical angle
When light travels from one medium to another it is refracted; it changes angle due to change in density. Past a certain angle the light will simply be refracted back into the medium it is in, this angle is the critical angle.
56
What is light?
a transverse wave
57
What are the characteristics of images in a plane mirror?
image is as far behind as the object is in front virtual same size laterally inverted
58
What is refraction?
when a ray of light travels from air into glass or water it slows down as it crosses the boundary between the two media. This change in speed may cause the ray to change direction; refract.
59
What is the formula for refractive index?
n = sin i / sin r n = speed of light in a vacuum / speed of light in material
60
What happens when the angle of incidence is less than the Ac?
A ray of light is refracted as it passes from a more dense medium to less dense one, but a small ray of light is also reflected.
61
What happens when the angle of incidence is equal to the Ac?
The light is refracted at 90 degrees to the normal and there is also a small reflected ray
62
What happens when the angle of i is more than the Ac?
TOTAL INTERNAL REFLECTION; light reflected back into the denser medium...no refraction occurs
63
What is the formula for the c?
sin c = 1/n
64
What can ruin the clear image in a plane mirror?
Several faint images form around the main image due to partial internal reflections at the non-silvered glass surface of the mirror
65
How are these extra faint images removed from the mirror?
When high quality images are required prisms are used to alter the direction of light rather than mirrors.
66
Where are prisms used?
bicycle reflectors and binoculars
67
What is an optical fibre made of?
an outer cladding of less optically dense glass and an inner core of optically dense glass
68
How is TIR achieved?
The fibres are very narrow so light entering the inner core always strikes the boundary of the two glasses at an angle greater than the Ac. No light escapes b/c all is Reflected.
69
What are large numbers of OP.FIBRES called?
bundle
70
What is done to bundles?
tapered to produce a magnified image
71
How does an endoscope work?
Light travels down one bundle and illuminates object to be viewed Light that is reflected by the object travels up a second bundle of fibres an image of the object is created by the eyepiece
72
How are optical fibres used in modern telecommunications?
Electrical signals from telephone converted to light pulses by tiny lasers The light pulses are sent into the ends of an op.fibres Light sensitive detector at the other end changes the pulses back to electrical signals These then flow into the telephone receiver; earpiece
73
What happens when white light passes through a prism?
it emerges as a band of colours; spectrum
74
Why is a spectrum formed?
White light is a mixture of colours and each colour travels through at a different speed so each colour is refracted by a different angle.
75
What is dispersion?
When each different colour of the spectrum emerges from the prism travelling in a different direction b/c each colour is refracted by a differing amount
76
Why does red light disperse the least?
The smaller the wavelength of the passing light, the greater is the refractive index observed. Therefore because red has the longest wavelength is deviates the least. The deviation depends directly on the refractive index. As white light passes through prism, violet, the minimum wavelength, observes maximum refractive index for the prism and since deviation depends directly on the ref index, the violet wavelength gets deviated to the maximum extent.

On the wild side (35 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions