Glass 0.0 / 5 ? CriminologyForensic StudiesUniversityOther Created by: AshleeCreated on: 03-05-15 21:18 What are the properties of glass? Variety of chemical compositions; transparent and translucent materials composed of fused inorganic materials 1 of 17 How does glass break? Struck; bends; fracture (radial); stress (concentric fractures); continues until stops 2 of 17 How do you collect glass at a crime scene? Take from window not floor; toughened = 50 pebbles; soda lime = 6 pieces 3 of 17 What is refractive index? Ration between speed of light in vacuum and speed of light through medium 4 of 17 What is the equation to work out RI? n = C/v 5 of 17 How is RI measured? Immersion method to see if the RI is the same as the oil around it 6 of 17 What is the RI of glass? 1.510 7 of 17 What is the probative value of glass? Physical, optical and elemental characteristics 8 of 17 What is soda lime glass composed of? Silica, soda and lime 9 of 17 What items are made of soda lime? Windows, drinks, containers 10 of 17 Why is toughened glass "tough"? High boron content; increased bending strength; resistant to thermal shock; super heated and rapidly cooled 11 of 17 When is toughened glass used? On car windows/windscreens 12 of 17 Why is glass of evidential value? Sequence of events; type of weapon used; direction of force; distribution of glass; associated evidence (victim, scene and suspect) 13 of 17 How would you analyse glass? Microscope; UV light 14 of 17 What would you specifically look for when analysing glass? Colour; thickness; curvature; fractures; uniformity; surface conditions; radial fractures; rear surface; right angles; backward fragmentation 15 of 17 What are the 3 rules when analysing glass? Radial fracture, right angles, rear surface 16 of 17 Why would you use UV light to analyse glass? Tin diffuses into glass due to float glass manufacture process and fluoresces under UV light 17 of 17
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