Waves Flashcards

1
Q

Def. Transverse wave

A

A transfer of energy where particles vibrate perpendicular to the wave’s direction of travel (propagation)

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2
Q

Def. Longitudinal wave

A

A transfer of energy where particles vibrate Parallel to the wave’s direction of travel

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3
Q

What are the components of a longitudinal wave?

A
  • Compression
  • Rarefaction
  • Wavelength
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4
Q

What are the components of a transverse wave?

A
  • Peak
  • Trough
  • Amplitude
  • Wavelength
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5
Q

Def. Frequency

A

Number of waves produced each second. Measured in Hertz (Hz)

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6
Q

Def. (Time) Period

A

Time taken for one whole wave to pass a point in space

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7
Q

Def. Wave

A

Transfer of energy from one place to another

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8
Q

What is the wave equation?

A

v = fλ

v = Wave speed (m/s)
f = frequency (Hz)
λ = Wavelength (m)

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9
Q

Pronounce λ

A

“Lambda”

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10
Q

What is the relationship between frequency and wavelength?

A

Inversely proportional

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11
Q

What can be assumed about wave speed?

A

When a specific wave travels through a specific substance, it always goes at the same speed

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12
Q

Def. What is the law of reflection?

A

The angle of incidence is equal to the angle of reflection

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13
Q

What are the characteristics of an image from a plane mirror?

A
  • Same size
  • Same distance
  • Virtual
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14
Q

Def. Refraction

A

The bending of light as it travels between 2 different mediums with a different refractive index

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15
Q

What is the formula to find the refractive index?

A

n = sinϴI/sinϴR

n = Refractive index
ϴI = Angle of incidence
ϴR = Angle of refraction

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16
Q

What is the approximate refractive index of:
- A vacuum
- Air
- Glass

A
  • Vaccum - 1
  • Air - Slightly higher than 1
  • Glass - ~1.5
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17
Q

Which way does light bend if it travels from a low refractive index to a high refractive index?

A

Light bends towards the normal

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18
Q

Which way does light bend if it travels from a high refractive index to a low refractive index?

A

Light bends away from the normal

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19
Q

Which colour has the highest frequency?

A

Blue

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20
Q

Def. Focal point

A

The point where parallel light rays converge after they are refracted

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21
Q

Where do virtual images form?

A

Where light rays appear to come from

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22
Q

Explain what happens when parallel light rays pass through a Convex/Converging lens

A

They are refracted inwards and meet at the focal point

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23
Q

Explain what happens when parallel light rays pass through a Concave/Diverging lens

A

The rays are refracted outwards and never meet

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24
Q

What are the 2 types of lenses?

A

Convex/Converging

Concave/Diverging

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25
What are the six possible characteristics of an image?
- Enlarged/Diminshed - Upright/Inverted - Real/Virtual | This vocabulary must be used
26
What kind of lens is in the eye?
Convex/Convergent
27
What kind of image is projected into the eye?
Real, Inverted and Diminished
28
Name the 2 important parts of the eye
- Lens - Retina
29
Where would light focus in a normal eye?
Right on the retina
30
Where would light focus in a short-sighted eye?
Short of the retina
31
Where would light focus in a long-sighted eye?
Far behind the retina
32
What kind of lens is needed to correct long-sightedness?
Convex
33
What kind of lens is needed to correct short-sightedness?
Concave
34
What is the critical angle?
The angle at which the angle of incidence is equal to when the angle of refraction is 90 degrees
35
What is the formula to find the refractive index of a substance using the critical angle?
n = 1/sin(ϴc) ## Footnote ϴc = Critical angle
36
What happens when the angle of incidence is larger than the critical angle?
Instead of refracting, the ray of light reflects internally
37
What are the uses of total internal reflection?
- Fibre optic cables - Tube to transport data at lightspeed - Endoscopes - Tube to see inside the human body
38
How do fibre optic cables work?
The rays of light bounce/zigzag throught the cables, being reflected internally continuously as the angle of incidence is too large.
39
When does total internal reflection occur?
- The angle of incidence is greater than the critical angle - The incident material is denser than the second material
40
What is the approximate speed of light?
3.0 x 108 m/s
41
What are electromagnetic waves?
Transverse waves that do not rely on the vibration of particles, and can travel through vaccums. They are vibrations in linked electric and magnetic fields moving through space
42
Are there differences in electromagnetic waves?
They all travel through space the same way, but with differerent wavelengths and they are produced and detected in diferent ways.
43
Name the sections of the electromagnetic spectrum from largest to smallest frequency
Radio waves Microwaves Infrared Visible light Ultraviolet X-rays Gamma rays
44
Name the sections of visible light from largest to smallest frequency
Red Orange Yellow Green Blue Indigo Violet
45
What are the uses of radio waves?
- Communication (Radio, TV) - RFID (Radio Frequency Indentification Tags)
46
What are the uses of Microwaves?
- Heating food - Cell phone communication - Satellite communication
47
What are the uses of infrared?
- Heating - Remote controls - Alarms (In beams that cannot be seen) - Thermal imaging
48
What are the uses of visible light?
- Sight - Photography - Illumination
49
What are the uses of Ultraviolet?
- Sterelisation of food and water - Picking up forgery
50
What are the uses of X-rays?
- Medical imaging - Airport security scanners
51
What are the uses of Gamma Rays?
- Quality control - Imaging applications - Cancer treatment - Food sterelisation
52
What are the dangers of Radio Waves?
No significant side effects
53
What are the dangers of Microwaves?
- Heating of cells, which leads to cell death and denaturing of enzymes
54
What are the dangers of infrared?
- Skin burns
55
What are the dangers of Visible Light?
No significant side effects
56
What are the dangers of Ultraviolet?
Damage of cells, DNA and eyes, which can lead to cancer or eyesight degradation
57
What are the dangers of X-rays and Gamma Rays?
- DNA damage, which can lead to mutations - General cell damage
58
What is the formula for the refractive index concerning the speed of light?
n = c/v ## Footnote n = Refractive Index c = Speed of light (3x108m/s) v = Current velocity of wave (m/s)
59
Explain in terms of wavefronts why light changes direction as it enters a solid
One side of the wavefront hits first and slows down, while the other faster side pivots around the slower edge. This causes the whole wavefront to bend and change direction until it is all at the same speed.
60
Def. Sound waves
Vibrations that allow energy to travel through a medium
61
What type of wave is a sound wave?
Longitudinal
62
How does the speed of sound change as the medium get denser?
Increases
63
What is the approximate speed of sound travelling through air?
≈330-350m/s
64
What is the approximate speed of sound travelling through water?
≈1500m/s
65
What is the approximate speed of sound travelling through steel?
≈3100m/s
66
What is the loudness of sound equal to?
Amplitude
67
What is the pitch of a wave equal to?
Frequency
68
What is the human hearing range?
20-20000Hz
69
What are the uses of ultrasound?
- Sonars - Medical imaging of soft tissues
70
What is the frequency of an ultrasound wave?
Frequency > 20000Hz