Unit 2: Waves and Radiation Flashcards

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1
Q

What is a Wave?

A

Something that transfers energy from one point to another

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2
Q

Transverse Wave

A

Particles of the medium vibrate at right angles to the direction the energy travels.

Examples: E-M Waves + Water Waves

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3
Q

Longitudinal Waves

A

Energy travels along in the same direction as the particles vibrate.

Example: Sound Waves

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4
Q

Wavelength

A

DIstance from a point to the point the wave begins to repeat itself. Could be from peak to peak or trough to trough. Measured in metres(m) and has the symbol λ

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5
Q

Frequency

A

Number of waves produced in 1 second by the source producing the wave. Measured in Hertz(Hz) and has the symbol f

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6
Q

Amplitude

A

Half the distance from peak to trough or the height of the wave from rest position. Measured in metres(m)

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7
Q

Wave Speed

A

How quickly the wave travels from its source. Is value is the same as distance travelled in one second. Measured in metres per second(ms-1) and has the symbol v

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8
Q

Period

A

Time taken for one complete wave to be produced. Also time taken for one whole wave to pass a point. Measured in seconds(s) and has the symbol T

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9
Q

Speed of Sound in Air

A

340 ms-1

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10
Q

Speed of Light in Air

A

3x108 ms-1

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11
Q

Diffraction

A

The spreading out of waves when they go through a gap or past the edge of a barrier

The greater the wavelength, the greater the diffraction

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12
Q

Electromagnetic Spectrum

A

Consists of a group of radiations that all travel at the speed of light

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13
Q

Visible Spectrum

A

Consists of a range of different colours of light that the human eye can detect. ROYGBIV

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14
Q

Radio Waves

A

At one end of the E-M spectrum. Greatest Wavelength. Lowest Frequency.

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15
Q

Gamma Ray

A

At one end of the E-M spectrum. Shortest Wavelength. Greatest Frequency.

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16
Q

Radio Waves Source

A

Electronic Circuits

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17
Q

Radio Waves Detector

A

Aerial

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18
Q

Radio Waves Typical Uses

A

Communications, Radio, TV

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19
Q

Microwaves Source

A

Electronic Circuits

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20
Q

Microwaves Detector

A

Aerial

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21
Q

Microwaves Typical Uses

A

Communications Satellites

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22
Q

Infrared Sources

A

Electronic Devices

Warm Objects, Sun

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23
Q

Infrared Detectors

A

Electronic Detectors

Heat-Sensitive Papers

Black-Bulb Thermometer

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24
Q

Infrared Uses

A

Remote Controls

Detector in Security Lighting

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25
Q

Visible Light Sources

A

Sun

Electronic Devices

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26
Q

Visible Light Detectors

A

Eyes

Photographic Film

LDR

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27
Q

Visible Light Typical Uses

A

Seeing

Photography

Communication (Optical Fibres)

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28
Q

Ultraviolet Sources

A

Sun

Gas Discharge

Lamps

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29
Q

Ultraviolet Detector

A

Film

Causes Fluoresence in Some Objects (Money)

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30
Q

Ultraviolet Uses

A

Sun-Tan Lamp

Making Ions

Killing Bacteria

Making Vitamin D

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31
Q

X-Rays Sources

A

Very Fast Electrons Hitting a Metal Target

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32
Q

X-Rays Detector

A

Photographic Film

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33
Q

X-Rays Uses

A

Imaging Defects in Bones

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34
Q

Gamma Rays Sources

A

Radioactive Nuclei Decaying

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35
Q

Gamma Rays Detectors

A

Photographic FIlm

G-M Tube

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36
Q

Gamma Rays Uses

A

Killing Cancerous Cells

Sterilisation of Surgical Equipment

37
Q

Refraction

A

The changing of speed (and often direction) of a light ray or a wave when it moves from one medium to another

38
Q

Normal

A

Imaginary line perpendicular to the substance the ligh is entering

39
Q

Angle of Incidence

A

Angle at which light hits the new medium. Taken from Normal to Incident Ray

40
Q

Angle of Refraction

A

Angle at whcih light rravels in new medium. Taken from Normal to Refracted Ray

41
Q

Convex Lens

A

Curves Outwards

Converges (Focuses) Light

Positive Power and Focal Length

42
Q

Concave Lens

A

Curves Inwards

Diverges (Spreads out) Light

Negative Power and Focal Length

43
Q

Retina

A

Light Sensitive Cells on the back of the eye. Light should converge at this point for a clear image

44
Q

Long-Sightedness

A

Eye Lens Not Powerful enough

Corrected using a Convex Lens

Able to focus on distant objects but not close objects

45
Q

Short-Sightedness

A

Eye Lens Too Powerful

Corrected using Concave Lens

46
Q

Ray Diagram Object > 2F

A

Image is:

  • Real
  • Inverted
  • Diminished
47
Q

Ray Diagram Object at 2F

A

Image is:

  • Real
  • Inverted
  • Same Size
48
Q

Ray DIagram Object < 2F

A

Image is:

  • Real
  • Inverted
  • Magnified
49
Q

Ray Diagram Object <f>
</f>

A

Image is:

  • Virtual
  • Right Way Up
  • Magnified
50
Q

Critical Angle

A

When the angle of incidence reaches this the angle of refraction=90º

51
Q

Total Internal Reflection

A

When the angle of incidence is greater than the critical angle and the light is reflected back into the medium. (No Light Refracted)

52
Q

Fibre Optic

A

Used to transmit light signals through a series of Total Internal Reflections

53
Q

Fibre Optic Advantages

A

Very Little Energy Lost

Huge signal Capacity - can carry many TV Channels/Telephone Lines

Secure - No signal escapes out of the edges

Cheaper,Lighter and more Flexible than copper wires

54
Q

Fiber Scope (Endoscope)

A

Allows doctor to see inside patient using bundles of fibre optics

55
Q

Alpha Particles (α)

A

Made of 2 protons and 2 neutrons (identical to helium nucleus). Heavy and Positively charged

56
Q

Beta Particle (β)

A

Made of 1 very fast moving electron. Light and negatively charged

57
Q

Gamma Ray (γ)

A

Part of the E-M spectrum. Has no mass, travels at the speed of light and has a very high frequency so a very high energy

58
Q

Other types of Nuclear Radiation

A

X-Rays, Fast and Slow moving Neutrons

59
Q

Ionisation

A

When an atom loses or gains an electron giving it a charge

60
Q

Ionising Radiation

A

Heavier Radidation is more ionising. Alpha most. Gamma least

61
Q

Alpha Penetration

A

Stopped by a few cm of air or a thin sheet of paper

62
Q

Beta Penetration

A

Stopped by a thin sheet of aluminium

63
Q

Gamma Penetration

A

Stopped by Lead or Concrete

64
Q

Ways of Detecting Nuclear Radiation

A

Geiger-Müller Tube

Film Badge

Scintillation Counter

Cloud Chamber

65
Q

Geiger-Müller (GM) Tube

A

Tube has a high voltage applied to central rod. Low pressure gas is sealed inside.
When radiation enters it ionises an atom of the low pressure gas, causing a current to flow

More radiation means a larger current

Doesn’t distinguish between types of radiation

66
Q

Film Badge

A

Badge has photographic film sealed in a lightproof plastic envelope.

Badge has different windows that allow different types of radiation through.

When radiation enters through the window it ionises the photographic film causing it to fog

67
Q

Sources of Radiation

A

40% Radon Gas from Ground

18% Artificial Sources

15% Rocks

15% Human Body + Food

12% Cosmic Rays

68
Q

Uses of Nuclear Radiation

A

Smoke Alarms

Carbon Dating

Paper Thickness Measuring

Detecting Leaking Pipes

Sterilising Hospital Equipment

Radiotherapy

69
Q

Smoke Alarms

A

Alpha Particles ionise the air causing a small current to flow. When smoke enters it absorbs the alpha particles causing the curent to reduce and the alarm to sound

70
Q

Paper Mills

A

Paper Thickness measured by how much beta radiation passes through the paper.

71
Q

Radiotherapy

A

Gamma Rays used to kill cancer cells

72
Q

Radiation Safety Rules

A

Keep time of exposure to a minimum

Hold radioactive sources using tongs

Wear protective clothing

73
Q

Absorbed Dose

A

Energy absorbed per kilogram. Measured in Greys(Gy) and has the symbolD

74
Q

Dose Equivalent

A

Takes into Account the radiation expoesed to. Measured in Sieverts(Sv) and has the symbol H

75
Q

Safe Radiation Dose

A

5mSv for general public

76
Q

Activity

A

Number of nuclei that decay every second. Measured in Bequerels(Bq) and has the symbol A

77
Q

Half-Life

A

Time taken for the activity of a source to halve

78
Q

Fission

A

When a large nucleus (such as uranium) splits into two smaller nuclei plus a few neutrons. Energy released very large (E=mc2)

79
Q

Nuclear Power Stations

A

Use nuclear fission to produce huge amounts of energy. Fission occurs in uranium fuel rods

80
Q

Moderator

A

Slows down neutrons so they can go on to cause further reactions

81
Q

Nuclear Power Advantages

A

Huge amount of energy produced from a small amount of fuel

Reaction produces no pollution

Running costs are small compared to running costs of a coal fired power station

Fraction of waste produced compared to coal

82
Q

Nuclear Power Disadvantages

A

Waste is highly reactive with a long half life

Massive start up costs. Expensive to decomission

Risk of nuclear accients that could release huge amounts of radioactive material intp environment. (Fukashima,Chernobyl)

83
Q

Fusion

A

When two small nuclei join together to form a larger one, releasing a huge amount of energy

84
Q

Fusion Advantages

A

Huge amount of energy produced using a small amount of fuel

A fraction of waste is produced compared to the waste from coal

Waste is helium - a harmless gas

85
Q

Fusion Disadvantages

A

Only happens at very high temperatures

Containing fuel at high temperatures isn’t possible with current technology

More research needs to be done

86
Q

If angle of incidence < critical angle

A

The light refracts

87
Q

If angle of incidence = critical angle

A

Refracted ray travels along the surface of the denser medium

88
Q

If angle of incidence > critical angle

A

Total Internal Reflection occurs