3 WAVES Flashcards

(61 cards)

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
Common features of EM waves
All travel at 3x10 8 m/s, can be reflected/refracted and can travel through a vacuum
26
Uses of Radio Wave
Broadcasting and communication
27
Uses of Microwave
Cooking and satellite transmissions
28
Uses of Infrared
Heaters and night vision equipment
29
Uses of visible light
Photography and optical fibres
30
Uses of Ultraviolet
Fluorescent lamps and tanning beds
31
Uses of X-rays
Observing the internal structures of objects, and can be used medically
32
Uses of gamma rays
Sterilising food and medical equipment
33
Dangers of radio waves
No known dangers
34
Dangers of microwaves
Internal heating of body tissues
35
Dangers of infrared
Skin burns
36
Dangers of visible light
Eye damage
37
Dangers of ultraviolet
Damage to surface cells and blindness
38
Dangers of x-rays
Cancer and mutation
39
Dangers of gamma rays
Cancer and mutation
40
Law of reflection
angle i = angle r
41
Ray diagram: Check list
* Draw a normal at 90 to where the incidence ray hits * Arrow all rays * Label all angles * Label values of all angles
42
Define refraction
The bending of a wave and changing of direction, as it changes speed
43
What happens when a light goes from air to glass
* Light bends towards normal * Speed and wavelength decrease * Frequency remains the same
44
What happens when a light goes from glass to air
* Light bends away from normal * Speed and wavelength increase * Frequency remains the same
45
Refractive index equation
n = sin i / sin r
46
Symbol for refractive index
n
47
PRACTICAL: How to obtain a trace diagram for a light ray
* 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
PRACTICAL: How to obtain refractive index of object
* 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
Conditions for T.I.F
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
Conditions for T.I.R
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
T.I.F is used in fibre optics. How a re fibre optics specialsied
Thin, and are made of a high refractive index material
52
Uses of fibre optics
* Communications (in cable TV and broadband) * Endoscopes for medicine
53
What is the critical angle
Critical angle equals angle of incidence when the ange of refraction is 90
54
Critical angle equation
sin c = 1 / n
55
Symbol for critical angle
c
56
Human hearing range
20 - 20,000 Hz
57
What does pitch correlate to
Frequency
58
What does amplitude correlate to
Volume
59
PRACTICAL: How to find the speed of sound in air
* 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
How to calculate time period from an oscilloscope (and then frequency)
Multiply the time base by however many it takes for a complete wave to occupy it, then use F = 1/T equation
61
PRACTICAL: Obtain frequency from an oscilloscope
* 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