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What is the state of matter of glass at room temperature?

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Presentation on theme: "What is the state of matter of glass at room temperature?"— Presentation transcript:

1

2 What is the state of matter of glass at room temperature?

3 It is an amorphous solid.

4 The main compounds in glass are __________.

5 Silicon Oxides & Metal Oxides

6 What is the name of the glass that is made by passing the molten glass through rollers?

7 Ordinary or rolled glass

8 Window glass is (more/less) dense than water.

9 More dense

10 The two most important physical properties of glass used for identification are:

11 Density and refractive index

12 True or False Density is not homogeneous over sheet of glass

13 True

14 True or False, when glass shatters it is easy to reconstruct the original shape.

15 false

16 This type of glass involves a treatment where the glass is heated to 620 o C and then cooled rapidly. What is the name of this glass?

17 Tempered or Safety Glass

18 Name the type of glass that is used for flat glass, container glass, and electric light bulbs.

19 Soda Lime Silicate

20 The fracture pattern of glass usually has __________ lines.

21 Conchoidal

22 This type of conchoidal line appears first when glass is fractured.

23 Radial

24 For a ______________ fracture, the perpendicular end, faces the surface on which the force originated.

25 concentric

26 In a forensic laboratory, a technique frequently used to determine the density of glass involves the use of ___________

27 Density – Gradient tubes

28 Stress marks on the edge of a radial crack near the point of impact are ___________ to the side on which the force was applied.

29 parallel

30 True or False A crater-shaped hole is narrower on the side where the projectile entered the glass.

31 True

32 True or False – It is easy to determine from the size and shape of a hole in glass, whether to was made by a bullet or some other projectile.

33 False

34 A piece of window glass is submerged in vegetable oil. The outline of the glass is visible. When light is shown behind the glass, a bright halo appears near the border of the glass. This bright halo is called a _________.

35 Becke line

36

37 Laminate or laminated

38 Name at least one out of three common problems associated with glass analysis (glass comparisons)

39 Find and measure properties Associate one glass fragment with another Minimize or eliminate other sources

40 The bending of light as it travels through one medium into another is known as ________.

41 Refraction

42 As light goes from the air into a liquid sample, the bending of light is due to a(n) ___________ in velocity of the light.

43 decrease

44 At 25 o C the refractive index of water is 1.333. This means that light travels 1.333x __________ in a vacuum than in water.

45 Faster

46 ______________ solids Refract a beam of light in two different light-ray components (wavelengths) Results in double refraction

47 Crystalline

48 The numerical difference between these the two refractive indices of a crystalline solid is known as ________________.

49 Birefringence

50

51

52 Technique used to determine the refractive index of a glass sample is known as the _____________ method.

53 Immersion

54 As the velocity of a fast moving projectile decreases, the irregularity of hole and cracks ____________.

55 increase

56

57 Radial

58 True or False All broken glass at a crime scene must be collected, regardless of the size.

59 Know ALL of these steps for Glass collection Collect all glass found for piecing Submit all glass evidence found in the possession of the suspect Collect only a representative sample of broken glass remaining at the crime scene

60 True or False Once collected glass should be wrapped up in paper to prevent further damage.

61 False, Packaged in solid containers to avoid further breakage

62 Standard/reference soils should be taken from the crime scene at various intervals within a ______-yard radius of the crime scene. This will be used as a comparison to questioned soil.

63 100

64 Soil is a mixture of _______ and _________ material.

65 Soil is a mixture of organic and inorganic material.

66 An example of 100% inorganic soil is _________while an example of a nearly 100% organic soil would is ________.

67 An example of 100% inorganic soil is sand while an example of a nearly 100% organic soil would is peat.

68 The inorganic part of soil is ________.

69 minerals

70 The organic part of soil is known as _______ which is made up of __________________.

71 Humas decayed plant and animal material

72 The forensic definition of soil includes many things, including:

73 1.Bits of grass 9. Seeds 2.Cinders 10. Animal matter 3.Asphalt 11. Spores 4.paint 5.metals 6.concrete 7.Bricks 8.Vegetation

74 List the five major factors that influence a soils composition.

75 1.Climate 2.Parent material 3.Living organisms 4.Topography 5.Time

76 True or False Soil is class evidence - cannot be individualized to a particular location

77 True

78 True or False There is no classification system for soils

79 True – only guidelines

80 True or False Soils can be easily transported

81 True – which makes it excellent trace evidence.

82 True or False Soils within a few meters horizontally or vertically differ

83 True

84 True or False After removing the first 2- 3 inches of top soil, a forensic soil analyst can tell if a body has been buried below.

85 True


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