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Forensic 1 > Chapter 2 > Flashcards

Chapter 2 Flashcards

1
Q

Light This refers to:

A
  1. Electromagnetic radiation ;and
  2. Radiant Energy
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2
Q

within the portion of the electromagnetic spectrum that can be perceived by the human eye

A

Electromagnetic radiation

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3
Q

makes things visible is classified by the wavelength into a system known as the electromagnetic spectrum

A

Radiant Energy

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4
Q

Natural Light source

A
  1. Moon and Star;
  2. Sunlight
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5
Q

Source of Light

A
  1. Natural Light source;and
  2. Artificial Light Source
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6
Q

It is when the sun sets, day turns into night and it becomes dark.

A

Moon and Star

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7
Q

The most popular and mostly used light source of photographers. It is free and no need to be transported. But it is not always there where we want it. It is uncontrollable but can be controlled using the camera controls

A

Sunlight

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8
Q

Classification According to it’s Intensity

A
  1. Bright sunlight/ Distinct Sunlight
  2. Hazy Sunlight
  3. Dull Sunlight/Cloudy
  4. Overcast Sky/ Cloud Bright
  5. Heavy overcast/ Cloud Dull
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9
Q

This is the direct sunlight striking the subject. It is the brightest of all, it is highly directional, images taken with distinct sun is characterized by extreme highlights and deep shadows and it provides the highest contrast in a picture

A

Bright sunlight/Distinct sun

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10
Q

It is a hazy sunlight when the sun is covered by thin clouds but still clearly visible and it is illuminating your subject, it produces soft shadows and moderate highlight and contrast is also moderate, while rays are directional.

A

Hazy Sunlight

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11
Q

Objects in open space cast no shadow. It is cloudy when the sun is shining bright but covered with thick moving clouds, other parts of the sky maybe clear, lighting is even throughout and not directional, it does not cast practical shadows on your subject and contrast is relatively fair.

A

Dull Sunlight/ Cloudy

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12
Q

Sun is bright but not visible, light is soft and not directional, skies may be covered with stationary clouds and it provides no shadows and low contrast

A

Overcast Sky / Cloudy Bright

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13
Q

This is practically the same as overcast sky but generally darker and light is dull. It provides very poor contrast and static cloud is so thick where one cannot tell the overhead position of the sun.

A

Heavy Overcast/Cloudy Dull

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14
Q

Light sources of this category are man-made and are divided into the
continuous radiation and the short duration. Continuous radiation, those that can give illumination continuously, short Duration and it gives a brief flash of light produced by a burning metallic wire (flash bulb) or an electrical discharge through a gas – filled tube (electronic flash). There are different classifications

A

Artificial Light Source

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15
Q

this refers to some units are portable battery operated and are easily carried and can meet the rugged and rigorous demand for field work

A

UV Lamp

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16
Q

This refers to Light Amplification through Simulated Emission of
Radiation. By illuminating certain items with LASER, they would fluoresce or could be made to stand out in sharp contrast from their background. This was especially significant in locating dried biological items

A

LASER

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17
Q

This refers to far more expensive alternative to forensic LASER. It uses a variety of band pass filters to provide a high intensity beam of non – coherent light.

A

Alternative Light Source (ALS)

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18
Q

This refers to a wide variety of relatively inexpensive light sources which use filtered white light.

A

.Forensic Light Sources (FLS)

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19
Q

Continues Radiation

A
  1. Carbon Arc
  2. Incandescent
  3. Photoflood lamps
  4. Fluorescent Lamps
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20
Q

This refers to a pair of carbon rods connected in series with a resistance across direct current.

A

Carbon Arc

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21
Q

This refers to a conducting filament enclosed by a glass bulb heated by the electric current until emits lights.

A

Incandescent

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22
Q

This refers to lamps that can be placed up very high producing deep shadows underneath protruding surfaces, if subject is a person standing, he will appear gloomy and sombre. These can be placed to shine from below giving mysterious and strange effects of frights to observers of the picture.

A

Photoflood lamps

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23
Q

This refers to illumination in an electric discharge lamp of the mercury – vapor type. The coating fluoresces and sends out light of low brilliance with visible zone.

A

Fluorescent Lamps

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24
Q

Short Duration Radiation

A
  1. Chemical Flash Lamp
  2. Electronic Flash Lamp
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25
Q

This refers to light that produces by the rapid burning of metal wire, foil or primer powders. To produce a rapid and complete burning, the bulb is charged with O2, the lamp flashed once.

A

Chemical Flash Lamp

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26
Q

This is consisting of a slender glass tube filled with a gas (Xenon), a high voltage electrical discharge is passed through coiled tube, causing the gas to glow.

A

Electronic Flash Lamp

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27
Q

Light Angles

A
  1. Front Lighting
  2. Side Lighting
  3. Back Lighting
  4. Overhead Lighting
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28
Q

Distinct sun is used as front lighting when it comes from behind the photographer. It is a common belief that photographs taken at early in the morning or late in the afternoon is better compared to photos taken in any other time of day. The light, when the sun is low, is oftentimes described as magical. Colors are warm, shadows are long, and subject glow with razor sharp clarity.

A

Front Lighting

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29
Q

This type of lighting happens mostly in the morning and afternoon when the sunlight hits the subject from either the right or left flank of the photographer. It brings out textures, patterns, and shapes of objects.

A

Side Lighting

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30
Q

This type of lighting happens when the sun strikes the subject from behind or when the sun is directly in front of the photographer. Light coming straight from the back of the subject in portrait produces a bright edged outlined around it. Backlighting also brings out shapes and good profile as well as silhouettes of your subjects

A

Back Lighting

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31
Q

This normally occurs at noontime where sun is directly above your subject. This angle of lighting is generally not recommended for taking portraits. Strong dark shadows are cast at the subjects’ eyes. However, it can be corrected with a fill – in flash.

A

Overhead Lighting

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32
Q

Theories of Light

A
  1. Wavelength of Light
  2. Quantum Theory
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33
Q

When incident light hits a medium, three things might happen, the light maybe:

A

• Reflected
• Absorbed
• Transmitted

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34
Q

It occurs whenever an object changes the direction of a light wave but does not allow the wave to pass through it. Reflected light maybe Specular or Diffused. When light strikes the surface and rebound it is said to be reflected, and it is called incident light. The angle which it strikes is called incident angle

A

REFLECTION

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35
Q

It is the change in direction of a wave due to a change in its speed. This is most commonly observed when a wave passes from one medium to another. Bending of light when passing from one medium to another.

A

REFRACTION

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36
Q

It is described as the apparent bending of waves around small obstacles and the spreading out of waves past small openings. It is also described as the bending of light when it hits a sharp edge of an opaque

A

DIFFRACTION

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37
Q

Examples of Diffraction

A

a. CD or DVD
b. Hologram
c. Interference
d. Rectilinear
e. Absorption
f. Filtration
g. Polarization
h. Fluorescence
i. Transmission

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38
Q

act as a diffraction grating to form the familiar rainbow pattern we see when looking at a disk;

A

CD or DVD

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39
Q

A picture that changes when looked at from different angles) on a credit card

A

Hologram

40
Q

This refers to the color that can be produced by interference of light waves in thin film like soap bubbles or a film of oil floating in water.

A

Interference

41
Q

This refers to the nature of light that normally travels in straight line.

A

Rectilinear

42
Q

This refers to the nature of light to be absorbed in the process of dark surfaces.

A

Absorption

43
Q

This refers to the character of light to be altered from its colorless into visible state.

A

Filtration

44
Q

This refers to the process by which the vibration of light are confined to definite plane, the speed of light can be measured

A

Polarization

45
Q

This happens when molecules of the fluorescent material absorb energy at one wavelength and radiate it at another wavelength.

A

Fluorescence

46
Q

This refers to the light that passes through an object.

A

Transmission

47
Q

Medium of Lights

A
  1. Transparent objects
  2. Translucent objects
  3. Opaque Objects
48
Q

It allows sufficient visible light to pass through them that the object on the other side may be clearly seen. It transmits 90% or more of the incident light.

A

Transparent objects

49
Q

It allows light to pass, however diffuse it sufficiently that objects on the other side may not be clearly distinguished . In some cases the objects on the other side may be recognizable but sharp detail and outlines are obscured. It transmits 50% or less of the incident light

A

Translucent objects

50
Q

It is so greatly diffuse the light that recognizing the object on the other side is very difficult if not impossible.
It divert or absorb light.

A

Opaque Objects

51
Q

Simplistically, we can think of light travelling as a wave. A typical wave form (e.g., ripples on the surface of water) has crests (or peaks) and troughs (or valleys).

A

Wavelength

52
Q

The light that we see is only a part of a tremendous range of energy called the ?

A

Electromagnetic Spectrum

53
Q

Kinds of light in electromagnetic spectrum

A

a. Visible Lights
b. Invisible Lights

54
Q

Visible Lights

A

Red
Orange
Yellow
Green
Blue
Indigo
Violet

55
Q

It range from 685-605 mμ

A

RED

56
Q

It range from 605- 585 mμ

A

ORANGE

57
Q

It range from 585-560 mμ

A

YELLOW

58
Q

It range from 560-475 mμ

A

GREEN

59
Q

It range from 475-455 mμ

A

BLUE

60
Q

It range from 455-440 mμ

A

INDIGO

61
Q

It range from 440-405 mμ

A

VIOLET

62
Q

The light that cannot be detected by the naked eye is the invisible spectrum. The left region of the visible light is called the ultra violet region. The right region of the visible light is called infrared region which are too long in wavelength to excite the retina of the eye. It is detected by the skin as heat.

A

Invisible Lights

63
Q

Invisible Radiation with wavelength shorter than 400 mμ

A
  1. Ultraviolet lights
  2. X-ray
  3. Gamma rays
  4. Cosmic rays
64
Q

It is used to photograph fingerprints on multi – colored background, documents that are altered chemically or over writings and detection of secret writings.

A

Ultraviolet lights

65
Q

electromagnetic energy having a wavelength that ranges between 10 – 30 millimicrons.Objects which are opaque as seen by the naked eye can be penetrated by x –rays.To produce a shadow photograph of an internal structure of solid objects, x –rays is suitable.

A

X-ray

66
Q

Used in recording or photographing objects hidden by opaque mediums

A

Gamma rays

67
Q

high energy charged particles, originating in outer space, that travel at nearly the speed of light and strike the Earth from all directions.
It also include high energy electrons, positrons, and other subatomic particles.
usually refers to galactic cosmic rays, which originate in sources outside the solar system, distributed throughout our Milky Way galaxy.

A

Cosmic rays

68
Q

Invisible Radiation with wavelength longer than 400 mμ

A
  1. Infrared Light
  2. Radio Waves
  3. Microwaves
  4. Hertzian Waves
69
Q

lights having wave length greater than 700 millimicrons. It wavelength ranges from 700 – 800 millimicrons.
It is not a color or any kind of red. It is an invisible rays and it is only
detected by the human skin as heat.
It is used in taking photographs of obliterated writing, burnt or dirty documents. Also known as “Blackout photography”.

A

Infrared light

70
Q

These light waves have the longest wavelength of all lights.
It is used for communicating through the modification and amplification of sound waves.

A

Radio Waves

71
Q

excite the water molecules in food, heat them up, and pass the heat throughout the food. It can harm the body because it can heat the water molecules in deep tissues.

A

Microwaves

72
Q

An electromagnetic wave produced by the oscillation of electricity in a conductor (as a radio antenna) and of a length ranging from a few millimeters to many kilometers.

A

Hertzian Waves

73
Q

The presence of all color

A

WHITE

74
Q

The absence of all colors or the absence of light

A

BLACK

75
Q

Primary colors of light rays

A
  1. Red
  2. Green
  3. Blue
76
Q

Secondary/ Contemporary colors of light rays

A
  1. Yellow
  2. Cyan
  3. Magenta
77
Q

Light rays

A
  1. Primary colors of light rays
  2. Secondary/Contemporary colors of light rays
  3. Color mixing of lights
  4. Color addition
  5. Color Subtraction
78
Q

Coloring Matters

A
  1. Primary colors of coloring Matters
  2. Secondary colors of coloring Matters
  3. Tertiary colors of coloring Matters
  4. Color mixing of coloring Matters
  5. Neutral Colors
79
Q

Primary colors of coloring Matters

A
  1. Red
  2. Yellow
  3. Blue
80
Q

Secondary colors of coloring Matters

A
  1. Orange
  2. Green
  3. Violet
81
Q

Tertiary colors of coloring Matters

A
  1. Yellow - orange
  2. Yellow - Green
  3. Blue - Green
  4. Blue - Violet
  5. Red - Violet
  6. Red - Orange
82
Q

Neutral Colors

A
  1. Gray
  2. Black
83
Q

Qualities of Light

A
  1. Intensity
  2. Color
  3. Direction
  4. Contrast
  5. Quality
84
Q

The amount of light reflected by the performer and the background. Also referred to as quantity of light and it refers to how bright or dim the light source is.

A

INTENSITY

85
Q

also known as the temperature of the light reflected by the performer and the background

A

COLOR

86
Q

The light determines the length and location of the shadows cast by the performer and the three dimensional props around him.

A

DIRECTION

87
Q

refers to the difference in brightness
between the brightest and darkest parts of the image which is the contrast between highlight and shadow areas. Highlights are the brightest parts of the image and shadows are the darker regions of an image

A

CONTRAST

88
Q

It is not something we can measure. It is, instead, something we describe based upon visual perception.

A

QUALITY

89
Q

the most pertinent, particularly in the design of lenses. It is best illustrated by the dropping of stone in a pond of still water. The series of wave which travels outward from the center point are just like wave that travels in all direction from a source with equal velocity. This theory maybe used to illustrate reflection, interference, refraction, diffraction and polarization.

A

Wavelength Theory

90
Q

Max Plank theorized in 1900 that light might be made up of little bundles of energy named quanta

A

Quantum Theory

91
Q

He measured the speed of light in 1976

A

OLE ROMER

92
Q

Forensic Light Source

A
  1. Latent Fingerprint Detection
  2. Bodily Fluids
  3. Hair and Fibers
  4. Questioned Documents
93
Q

The primary application of a forensic light source is for enhancing the detection of latent fingerprints. The use of fluorescent enhancement processes that compliment a light source greatly increases the types of surfaces from which a latent fingerprint can be detected.

A

Latent Fingerprint Detection

94
Q

It will actually glow under the light source illumination.

A

Bodily Fluids

95
Q

It will also glow under UV or visible light and will stand out strongly for collection

A

Hair and Fibers

96
Q

A tunable forensic light source can be used to identify slight variations in ink type by viewing ink responses as the color of the light is tuned through the visible and infrared regions.

A

Questioned Documents

Forensic 1 (3 decks)

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