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PHYSICS > Waves > Flashcards

Waves Flashcards

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1
Q

What is wavelength?

A

The distance from one peak to the next

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2
Q

What is frequency?

A

How many complete waves there are per second

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3
Q

What is Amplitude?

A

The height of the wave (from rest to crest)

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4
Q

What is the sped?

A

How fast the wave travels

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5
Q

What is the period?

A

The time it takes for one complete wave to pass a point

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6
Q

Wave speed=

A

Frequency (Hz) x Wavelength (m)

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7
Q

Example of transverse waves

A

Light and all other EM waves

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8
Q

What happens in a transverse wave?

A

The vibrations are at 90 degrees to the direction energy is transferred by the wave

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9
Q

What happens in a longitudinal wave?

A

The vibrations are along the same direction as the wave transfers energy

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10
Q

What do waves transfer?

A

energy and information without transferring matter

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11
Q

Name the EM waves in order of increasing frequency and decreasing wavelength

A 
Radiowaves
Micro-waves
Infa-red
Visible light
Ultra-violet
X-rays
Gamma Rays
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12
Q

What colour does the lowest frequency wave have?

A

red

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13
Q

What order is the Electromagnetic Spectrum colours in?

A

Rainbow (ROYGBIV)

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14
Q

What are radio waves used for?

A

Communication and Broadcasting

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15
Q

What are microwaves used for?

A

Satellite communication and Cooking

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16
Q

How to microwaves cook food?

A

Microwaves are absorbed by water molecules in food

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17
Q

What is infared radiation used for?

A

Heating and Night vision equiptment

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18
Q

What can visible light be used for?

A

Communication via optical vibres and Photography

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19
Q

How do cameras use a lens?

A

To focus visible light onto a light sensitive film or electronic sensor.

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20
Q

What are the uses of ultraviolet waves?

A

Used in fluorescent lamps

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21
Q

What are the uses of X-rays?

A

Used to view internal structures of objects and materials

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22
Q

How do radiographers and patients protect themselves from X-rays?

A

They wear lead aprons and shields

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23
Q

What is Gamma radiation used for?

A

Sterilising medical equipment and sterilising food

Treat certain types of cancer

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24
Q

Danger of microwave

A

Heat human body tissue

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25
Q

Danger of Infared

A

Skin burns

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26
Q

Dangers of Ultra-violet

A

Damage surface cells and cause Blindness

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27
Q

Danger of X-ray

A

Cell mutation and cancer

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28
Q

Danger of Gamma

A

Cell mutation and cancer

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29
Q

Angle of Incidence=

A

Angle of Reflection

30
Q

What type of wave is visible light?

A

Transverse

31
Q

What happens when light reflects from an uneven surface?

A

the light reflects off at all different angles and you get a diffuse reflection

32
Q

What is the surface of reflection called?

A

The NORMAL

33
Q

Waves travel at different…

A

speeds

34
Q

When are EM waves slower

A

in denser material

35
Q

What does white light disperse into?

A

different colors

36
Q

How can you work out the refractive index?

A

by measuring the angles between the rays and the normal

37
Q

What happens when you shine a light ray at an angle into a glass block?

A

Some light is reflected but a lot passes through the glass and gets refracted too

38
Q

(SNELLS LAW) n=

A

sin i/sin r

39
Q

What does the refractive index of a transparent material tell you?

A

how fast light travels in that material

40
Q

What equipment do you need to find total internal reflection?

A

a semi-circular block

41
Q

When does total internal reflection occur?

A

When the angle of incidence is greater than the critical angle

42
Q

sin C=

A

1/n

43
Q

Optical fibres use…

A

Total internal reflection

44
Q

What are optical fibres made of? and what do they consist of?

A

Plastic or glass, consisting of a central core surrounded by cladding that has a lower refractive index

45
Q

When would a optical fibre stop working?

A

If it was bent too sharply

46
Q

What can sound waves do?

A

reflect, refract and diffract

47
Q

What is the human ear capable of hearing frequencies of?

A

20-20,000 Hz

48
Q

What type of wave are sound waves?

A

Longitudinal

49
Q

When do sound wave travel fastest?

A

In dense material

faster in solids

50
Q

define the diffraction of waves

A

waves bend round edges and through gaps, causing the waves to spread out. This allows waves to travel round corners

51
Q

what does the amount of diffraction depend on?

A

the size of the gap relative to the wavelength of the wave

52
Q

what is the amount of diffraction like when a wave passes through a gap which is much wider than wavelength?

A

little diffraction occurs

53
Q

what is the amount of diffraction like when a wave passes through a gap which is a bit wider than wavelength?

A

diffraction occurs but only at the edges of the wave

54
Q

what is the amount of diffraction like when a wave passes through a gap which is the same size as wavelength?

A

maximum diffraction occurs

55
Q

are waves with longer wavelengths more adept to diffraction or less?

A

more

56
Q

what happens when waves encounter obstacles?

A

diffraction causes them to bend around the obstacle

57
Q

which of these can sound waves do?

a) reflect
b) refract
c) diffract

A

all three

58
Q

what is an oscilloscope?

A

a device which can display microphone signal as a trace on a screen

59
Q

if a wave has a high amplitude, what property will it have?

A

it will be loud

60
Q

what are the traces of louder sound waves like on an oscilloscope?

A

larger amplitude

61
Q

what is frequency?

A

the number of complete vibrations each second

62
Q

what is frequency measured in?

A

Hz - hertz

63
Q

the more complete cycles displayed on the screen of an oscilloscope, the higher/lower the frequency?

A

higher

64
Q

what is the pitch like of a source of sound that vibrates with a high frequency?

A

high-pitched

65
Q

what is the pitch like of a source of sound that vibrates with a low frequency?

A

low-pitched

66
Q

frequency =

A

1 / time period

67
Q

what is the horizontal axis on the display of an oscilloscope?

A

time

68
Q

what is the period of a wave?

A

the time taken for one complete cycle

69
Q

what is analogue signal?

A

can take any value within a certain range. The amplitude and frequency can vary continuously.

70
Q

what is digital signal?

A

can only take two values, usually called on/off or 1/0.

71
Q

what are three advantages of digital over analogue signals?

A
  1. when you amplify an analogue signal, the noise/interference from electrical disturbances or other signals is also amplified - so every time it’s amplified, the signal loses quality. With a digital signal, the noise is simply ignored, so the SIGNAL REMAINS HIGH QUALITY
  2. easier to transmit multiple signals at the same time with just one cable or EM wave- MULTIPLEXING. If the analogue waves are of similar frequency, it can cause interference when the signal loses quality. With digital signals its easier to tell them apart, so you can TRANSMIT MORE INFORMATION ALONG THE SAME CHANNEL
  3. quantisation is

PHYSICS (8 decks)

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