Forensic Science Glass (All Accurately solved)

Glass characteristics correct answers -Amorphous solid (meaning the structure can change) - made up of SiO2 (silicon and oxygen molecules) which is the chemical base of all glass - has a high melting pt at 2,000 C What are the different types of glass? correct answers 1. Float glass/ soda lima glass 2. Tempered glass 3. Borosilicate glass 4. Leaded glass (crystal) (tinted glass) Why is glass forensically important? correct answers - it's found at most crime scenes - it can be carried away from the scene undefected - it's stable and doesn't decay - it is class evidence What should you do with glass at a crime scene? correct answers Collect proper known samples so that incidental glass can be eliminated. When can glass be individual evidence? correct answers Usually it is class, but when there is a FRACTURE MATCH, it is individual. If you use a microscope it can help you with this. Also, if a glass has random stress patterns it is unique. What are the different types of analysis of broken glass? correct answers 1. sequence of fractures (order) 2. direction of force which caused fracture (inside to outside or v.v?) 3. the type of a small piece of glass- soda lime, borosilicate, tempered, or lead crystal glass What is the difference between radial and concentric fracture lines? correct answers Radial- occur extending outwards from break Concentric- form circle around break point How can you tell the direction of force (entry vs. exit?) correct answers entry: SMOOTH SIDE exit: ROUGH/CRATERED SIDE What are the class characteristics of glass that most labs can analyze? correct answers - physical characteristics - color - density - refractive index Density equation correct answers Mass/ volume Refractive Index correct answers ratio of velocity of light in a vacuum to its velocity in a medium (speed of light in a medium)