3 WAVES Flashcards

1
Q

Unit for temperature

A

Degrees

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2
Q

Unit for frequency

A

Hertz (Hz)

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3
Q

Unit for distance

A

Metre (m)

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4
Q

Unit for speed

A

Metre/second (m/s)

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5
Q

Unit for time

A

Second (s)

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6
Q

Difference between longitudinal and transverse wave

A

Transverse waves oscillate perpendicular (90) to the direction of wave travel, whereas longitudinal waves oscillate parallel to the direction of wave travel

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7
Q

Examples of transverse wave

A
  • Water waves
  • Electromagnetic (specific)
  • Seismic S wave
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8
Q

Examples of longitudinal wave

A
  • Sound
  • Shock
  • Seismic P wave
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9
Q

Define amplitude

A

Maximum displacement of oscillation from the equilibrium point

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10
Q

Define wavelength

A

Distance between 2 consecutive crests (on a transverse), or distance between 2 consecutive compressions (on a longitudinal)

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11
Q

Define time period

A

Time for one wave to pass a certain point

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12
Q

Define frequency

A

Number of waves that pass per unit time

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13
Q

Wave speed equation

A

Wave speed = wavelength x frequency

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14
Q

Wavelength equation

A

Wavelength = wave speed / frequency

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15
Q

Symbol for wave speed

A

v

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16
Q

Symbol for frequency

A

f

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17
Q

Law of waves

A

All waves transfer energy and information, without transferring matter

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18
Q

Frequency equation

A

Frequency = 1 / Time period

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19
Q

Time Period equation

A

Time period = 1 / frequency

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20
Q

Time period symbol

A

T

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21
Q

Define the doppler effect

A

The apparent change in frequency or wavelength of a wave for an observer moving relative to it’s source

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22
Q

Why do you hear a high then low pitch as a car approaches you?

A
  • As the car moves towards you, the wavefronts bunch up and the wavelength decreases
  • Speed of the car remains the same
  • v = f (X) means wavelength decreases, and frequency increases for the same speed
  • You hear a higher pitch
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23
Q

EM spectrum in increasing wavelength

A
  • Gamma
  • X-ray
  • Ultraviolet
  • Visible light
  • Infrared
  • Microwave
  • Radio wave
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24
Q

EM spectrum in decreasing wavelength

A
  • Radio wave
  • Microwave
  • Infrared
  • Visible light
  • Ultraviolet
  • X-ray
  • Gamma
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25
Q

Common features of EM waves

A

All travel at 3x10 8 m/s, can be reflected/refracted and can travel through a vacuum

26
Q

Uses of Radio Wave

A

Broadcasting and communication

27
Q

Uses of Microwave

A

Cooking and satellite transmissions

28
Q

Uses of Infrared

A

Heaters and night vision equipment

29
Q

Uses of visible light

A

Photography and optical fibres

30
Q

Uses of Ultraviolet

A

Fluorescent lamps and tanning beds

31
Q

Uses of X-rays

A

Observing the internal structures of objects, and can be used medically

32
Q

Uses of gamma rays

A

Sterilising food and medical equipment

33
Q

Dangers of radio waves

A

No known dangers

34
Q

Dangers of microwaves

A

Internal heating of body tissues

35
Q

Dangers of infrared

A

Skin burns

36
Q

Dangers of visible light

A

Eye damage

37
Q

Dangers of ultraviolet

A

Damage to surface cells and blindness

38
Q

Dangers of x-rays

A

Cancer and mutation

39
Q

Dangers of gamma rays

A

Cancer and mutation

40
Q

Law of reflection

A

angle i = angle r

41
Q

Ray diagram: Check list

A
  • Draw a normal at 90 to where the incidence ray hits
  • Arrow all rays
  • Label all angles
  • Label values of all angles
42
Q

Define refraction

A

The bending of a wave and changing of direction, as it changes speed

43
Q

What happens when a light goes from air to glass

A
  • Light bends towards normal
  • Speed and wavelength decrease
  • Frequency remains the same
44
Q

What happens when a light goes from glass to air

A
  • Light bends away from normal
  • Speed and wavelength increase
  • Frequency remains the same
45
Q

Refractive index equation

A

n = sin i / sin r

46
Q

Symbol for refractive index

A

n

47
Q

PRACTICAL: How to obtain a trace diagram for a light ray

A
  • Place the block of plain paper, and draw around it using a pencil, ensuring it doesn;t move
  • Allign the ray box so a single bean hits the block
  • Mark it’s entry and exit with a pencil
  • Join with a ruler
  • Add arrows, normal and other measurements with a protractor
48
Q

PRACTICAL: How to obtain refractive index of object

A
  • Place the block of plain paper, and draw around it using a pencil, ensuring it doesn;t move
  • Allign the ray box so a single bean hits the block
  • Mark it’s entry and exit with a pencil
  • Join with a ruler
  • Add arrows, normal and other measurements with a protractor
  • Measure angle i and r with a protractor
  • Repeat with at least 4 angles
  • Plot a sin i / sin r graph and the gradient = n
49
Q

Conditions for T.I.F

A
  1. Ray must be moving from high refractive index to low refractive index
  2. Angle of incidence must be greater than the critical angle
50
Q

Conditions for T.I.R

A
  1. Ray must be moving from high refractive index to low refractive index
  2. Angle of incidence must be greater than the critical angle
51
Q

T.I.F is used in fibre optics. How a re fibre optics specialsied

A

Thin, and are made of a high refractive index material

52
Q

Uses of fibre optics

A
  • Communications (in cable TV and broadband)
  • Endoscopes for medicine
53
Q

What is the critical angle

A

Critical angle equals angle of incidence when the ange of refraction is 90

54
Q

Critical angle equation

A

sin c = 1 / n

55
Q

Symbol for critical angle

A

c

56
Q

Human hearing range

A

20 - 20,000 Hz

57
Q

What does pitch correlate to

A

Frequency

58
Q

What does amplitude correlate to

A

Volume

59
Q

PRACTICAL: How to find the speed of sound in air

A
  • Make a noise heard over 100m like banging 2 wooden blocks together
  • Use speed = distance / time
  • Must have still air
  • Repeat and average
  • Stopwatch at zero and have clear visual signal
  • Meaure time taken of seeing block hit, and when heard
  • Factor in reaction time
60
Q

How to calculate time period from an oscilloscope (and then frequency)

A

Multiply the time base by however many it takes for a complete wave to occupy it, then use F = 1/T equation

61
Q

PRACTICAL: Obtain frequency from an oscilloscope

A
  • Connect microphone to input channel and turn on for a steady trace
  • Adjust time base, so there is a complete cycle on the screen
  • Measure squares (time base) for a complete cycle
  • Multiply number of squares by time ase, to find time period
  • Use F = 1/T to get frequency