Page 9 - Jagged Edge Glass Fragment

Pre-Lab

Solutions

1. What is trace evidence? 5. If the refractive index of a medium is known
Evidence created when two objects come in to be 1.50, and the angle of incidence is 46.8°,
contact with one another and transfer matter as what is the angle of refraction?
a result of that contact. n = sin /sin
1 2
1.50 = sin(46.8 °) / sin
2
sin =sin(46.8 °) / 1.50
2
2. What information can trace evidence provide? sin =0.486
2
Trace evidence can connect a suspect to a sin =29.1 °
victim, a suspect to a crime scene, and/or a 2
victim to a crime scene.
6. When placed in liquid of a different refractive
index, what is the bright outlining halo
3. What is commonly the first step in glass surrounding a glass fragment called?
analysis? Becke line
An attempted physical match.

7. What are two ways the atomic composition of
4. How is refractive index calculated? a glass fragment may be determined?
n = sin /sin
1 2 X-ray Diffraction (XRD) and LAser Ablation-
Where: n = Refractive Index Inductively Coupled Plasma-Mass
= Angle of Incidence
1 Spectrometry (LA-ICP-MS)
= Angle of Refraction
2

THE MYSTERY OF LYLE AND LOUISE 9