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waves Flashcards

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AP® Physics flashcards Physics 101 flashcards
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 pass per second

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3
Q

what is amplitude

A

the height of the waves, from equilibrium to peak

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4
Q

what is the period

A

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

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5
Q

speed=

A

frequency x wavelength

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6
Q

frequency =

A

1/T

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7
Q

transverse wave example

A

light
em waves §

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8
Q

what are transverse waves

A

vibrate perpendicular to the direction of travel

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9
Q

longitudinal wave example

A

sound
shock waves

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10
Q

what are longitudinal waves

A

vibrate in the same direction as the direction of travel

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11
Q

what do waves do

A

transfer energy and information without transferring matter

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12
Q

why does the Doppler effect make waves longer or shorter

A

the wave speed is constant, therefore when the source is moving the waves bunch up in front and spread out behind

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13
Q

how does the Doppler effect change frequency

A

in a source moving towards you the frequency will increase and wavelength will decrease

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14
Q

electromagnetic waves longest to shortest

A

radio waves
microwaves
infared
visible light
ultraviolet
X-rays
gamma rays

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15
Q

what happens as the em waves decrease in wavelength

A

frequency increases

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16
Q

what type of waves are em waves

A

transverse

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17
Q

what is the same about em waves

A

all transverse
all travel at the same speed through a vacuum

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18
Q

what affects the colour of visible light

A

the wavelength, red has the longest wavelength

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19
Q

em waves pneumonic

A

raging martians invaded Venus using xray guns

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20
Q

what are radio waves used for

A

communications

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21
Q

what are microwaves used for

A

satellite communication
heating food

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22
Q

what are inferred waves used for

A

heating
monitoring temperature

23
Q

what is visible light used for

A

photography

24
Q

what is ultraviolet used for

A

fluorescent lamps

25
Q

what are X-rays used for

A

viewing the internal structure of objects

26
Q

what is gamma used for

A

sterilising medical equipment and food

27
Q

dangers of microwaves

A

heat human body cells

28
Q

dangers of infrared

A

skin burns

29
Q

dangers of ultraviolet

A

damage to surface cells and blindness

30
Q

dangers of gamma rays

A

cell mutation, causing cancer

31
Q

law of reflection

A

angle of incidence = angle of reflection

32
Q

what is the angle of incidence

A

the angle between the incoming wave and the normal

33
Q

what is the angle of reflection

A

angle between the reflected wave and the normal

34
Q

what happens when em waves travel through substances of different densities

A

the wave speed changes
(slows through denser media)

35
Q

what happens when a wave meets a denser medium at an angle

A

the wave gets refracted

36
Q

experiment to show refraction

A

glass block experiment

37
Q

what happens when light is refracted through a triangular prism

A

white light disperses into different colours as the different wavelengths are refracted by different amounts

38
Q

what does the refractive index indicate

A

how fast light travels through a material

39
Q

refractive index =

A

speed of light in vacuum / speed of light in the material

40
Q

snells law =

A

refractive index = sin i / sin r

41
Q

what is total internal reflection

A

the complete reflection of a light ray reaching a surface with a less dense medium when the angle of incidence exceeds the critical angle

42
Q

what is used to demonstrate TIR

A

semicircular glass block

43
Q

how to find the critical angle

A

sinC = 1/n

44
Q

2 uses of total internal reflection

A

optical fibres
periscope

45
Q

how do optical fibres work

A

the core of the fibre is so narrow that light signals passing through always hit the boundary at angles higher than C, so the light is always totally internally reflected

46
Q

how do periscopes work

A

the ray of light travels into one prism where it is totally internally reflected by 90 degrees, then travels to another prism lower down and is totally eternally reflected by another 90 degrees

47
Q

what frequencies can the human ear hear

A

20 - 20,000 Hz

48
Q

how does density affect sound waves

A

the denser the medium the faster sound travels through it

49
Q

why can’t sound travel through a vacuum

A

there are no particles

50
Q

what displays sound waves

A

oscilloscope

51
Q

how does an oscilloscope work

A

a microphone converts sound waves to electrical signals displaying the signals as a trace on a screen

52
Q

what does a change in amplitude represent on an oscilloscope

A

loudness

53
Q

what does a change in frequency represent on an oscilloscope

A

the pitch

54
Q

how to measure the speed of sound using an oscilloscope

A
  • start with 2 microphones next to the speaker , then slowly move one away until the 2 waves are aligned on the display, exactly 1 wavelength apart
  • measure the distance between the microphones to find wavelength
  • use the equation speed = frequency x wavelength

physics (6 decks)

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