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physics > topic 6 - waves > Flashcards

topic 6 - waves Flashcards

1
Q

define wavelength

A

the distance of one entire oscillation of that wave

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2
Q

define amplitude

A

the maximum displacement from the equilibrium position

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3
Q

define time period in terms of waves

A

is the time is taken for one entire oscillation of a wave

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4
Q

what direction are the oscillations in waves?

A

transverse = perpendicular
longitudinal = parallel

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5
Q

depending on the conditions, what happens when a light hits a material?

A

it can be absorbed, reflected or transmitted

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6
Q

when does specular reflection occur?

A

when the boundary is flat

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7
Q

what type of image does specular reflection produce?

A

a clear image

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8
Q

when does diffuse reflection occur?

A

when the surface is bumpy

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9
Q

what is specular reflection?

A

when all the normals are in the same direction

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10
Q

what is diffuse reflection?

A

all the normals are different

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11
Q

what is the similarity between diffuse and specular reflection?

A

the angle of incidence = the angle of reflection

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12
Q

what is refraction?

A

refers to the change in direction of a wave, as it passes from one medium to another, and is caused by its change in speed.

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13
Q

what is the speed of light in a dense material?

A

slow

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14
Q

what type of waves are electromagnetic?

A

transverse

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15
Q

in a vacuum, what speed do electromagnetic waves travel at?

A

3x10(to the power of 8) m/s

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16
Q

describe radio waves wavelength and frequency.

A

long wavelength and low frequency

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17
Q

what do you use to remember the order of waves? and what order does this show?

A

Getley’s X Uses Lips In Maddy’s Room
- high to low wavelength
- low to high frequency
gamma, x-ray, uv, visible light, infrared, microwaves, radio waves.

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18
Q

what parts of the electromagnetic spectrum are ionising?

A

the last three: uv, x-ray, gamma ray.

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19
Q

what parts of the electromagnetic spectrum are used in communication?

A

the first two, radio and micro waves.

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20
Q

how are radio waves created?

A

using alternating current

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21
Q

what are oscilloscopes used to do?

A

display the wave frequency of an alternating current

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22
Q

what are three types of radio wave?

A

long, short and very short waves

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23
Q

what can long waves do?

A

can travel long distances and diffract (bend) around the curved surface of the earth

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24
Q

what are the two types of microwaves and what do they do?

A

absorbed by water molecules:
- ones that heat our food in the microwave
- energy is absorbed into the water molecules that make up most of our food
- particles therefore have more energy and vibrate more
- transferring energy to the neighbouring molecules.
- energy is spread throughout the food via conduction and convection

not absorbed by water molecules:
- used for communication
- doesn’t absorb water because it has to pass through the atmosphere where there are water vapour molecules
- from earth, then received by the satellites
- then transmitted back down to earth where they are picked up by satellite dishes.
- satellite TVs

25
Q

what are uses of infrared radiation?

A

infrared cameras:
- helps see in the dark and spot living organisms
- animals and humans give off heat, meaning they look warmer in the camera and their surroundings look cooler and darker

cooking:
- heat metal to very high temps
- ovens and grills especially
- emit lots of infrared radiation (doesn’t penetrate the surface of the food unlike in microwaves)
- then heats our food by transferring the heat energy causing it to cook

electric heaters:
- electrical energy heats metal
- emitting infrared radiation to the surroundings, heating up the room

26
Q

what is infrared radiation?

A

emitted from all objects that have thermal energy (depending on the objects temp)
- the hotter the object, the more infrared radiation it has

27
Q

when are microwaves and infrared waves harmful?

A
  • in high quantities
  • background radiation doesn’t do us any harm
28
Q

what are optical fibres used for?

A

to transmit data really quickly over very large distances

29
Q

what can UV light be used for?

A
  • check for invisible markings on passports
  • destroy microorganisms in water sterilisation
  • give sun tans
30
Q

what is fluorescence?

A

UV light energy being absorbed and re-absorbed as visible light

31
Q

how do x-rays work?

A
  1. x-rays are fired at the patient
  2. x-rays are absorbed by materials which are very dense, like bones
  3. x-rays are transmitted through materials which are not very dense, like lungs and intestines
  4. the x-rays that pass through are detected by a detector plate to form an x-ray image
32
Q

over a longer-term, who is the risk of overexposure to x-rays higher for?

A

hospital staff administering x-rays rather than patients because they are doing it all day every day, they remove themselves from the room and wear protective clothing, however they still end up with a larger dosage than the patients

33
Q

what are gamma rays used for in hospitals?

A
  • treating cancer
  • performing medical imaging
  • to sterilise medical equipment and food
  • also kills microorganisms without causing any other damage
34
Q

what are the properties of higher power lenses?

A
  • more curved
  • made of a material which refracts light more strongly
35
Q

describe a virtual image

A
  • light rays don’t come together where the image appears to be
  • the image cannot be captured on a screen
36
Q

describe a real image

A
  • light rays come together to form an image
  • the image can be captured on a screen
37
Q

what is white?

A

the combination of all colours

38
Q

what is black?

A

the absense of light

39
Q

what dies ROYGBIV show us about wavelength?

A

it is ordered from longest to shortest wavelength

40
Q

what does an opaque object not do?

A

transmit light

41
Q

what does an objects colour depend on?

A
  • wavelengths of light absorbed by the object
  • wavelengths of light hitting the object
  • wavelengths of light reflecting off the object
42
Q

what are the three colours of light?

A

red, blue and green

43
Q

why does an object appear the colour it is?

A

because it transmits the light it is and absorbs all the other colours of light

44
Q

what type of wave are sound waves?

A

longitudinal waves

45
Q

what are compressions?

A

where the vibrating particles are closest together

46
Q

what are rare fractions?

A

the regions where the vibrating particles are the furthest apart

47
Q

what order from slowest to fastest shows how fast sound waves travel?

A

fastest = solids
middle = liquids
slowest = gases

48
Q

what can sound waves be in context of coming into contact with an object?

A
  • absorbed
  • reflected
  • refracted
49
Q

what is the role of the ear drum?

A

to transmit the vibrations of the sound wave to the ossicles

50
Q

what is the range of human hearing?

A

20 to 20,000 Hz

51
Q

what is the role of the auditory nerve?

A

to transit the electrical signals form the cochlea to the brain

52
Q

what is the role of the cochlea?

A

convert the vibrations into electrical signals

53
Q

what is the frequency range of ultrasound?

A

above 20,000 Hz

54
Q

what do bats naturally produce ultrasound for?

A

communication and echolocation

55
Q

how can ultrasound be produced?

A

a speaker

56
Q

is ultrasound harmful?

A

no, it is safe

57
Q

how do you calculate the thickness of a medium using ultrasound?

A

use the time taken for the ultrasound to bounce back to the receiver

58
Q

what can ultrasound be used for?

A
  • to check for cracks in solid products, ultrasound would reflect off of the crack and be deflected
  • also as sonar by boats and submarines, reflect ultrasound off of the sea floor, calculating the distance from the sea floor.

physics (4 decks)

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