Forensic glass analysis review

Refraction index

a measure of how light bends as it passes from one substance to another

Density

the ratio of the mass of a substance to its volume, expressed by the equation X=mass/volume

Obsidian

volcanic glass

Glass

a hard, amorphous, transparent material made by heating a mixture of sand and other additives

amorphous

Without shape or form; applied to glass, it refers to having particles that are arranged randomly instead of in a definite pattern

Silicon dioxide

(SiO2) the chemical name for silica

Radial fracture

A crack in a glass that extends outward like the spoke of a wheel from the point at which the glass was struck

Becke line

line created as refracted light becomes concentrated around the edges of the glass fragment

Refraction

the change in the direction of light as it changes speed when moving from one substance into another

Concentric fracture

a crack in a glass that forms a rough circle around the point of impact

Leaded glass

glass containing lead oxide

Laminated glass

Two sheets of ordinary glass bonded together with a plastic film

Soda lime glass

The most common glass, which is inexpensive, and easy to melt and shape

tempered glass

glass that is strengthened by introducing stress through rapid heating and cooling of the glass surfaces

Sand

The main ingredient in glass

Tempered glass is used in...

The side and rear windows of autos manufactured in the United States.

Flotation is a method used by scientist to determine the ______ of a particle of glass

Density

When a bullet penetrates a panel of glass, it leaves a crater shaped hole that is...

Wider on the exit side

Which statement is true about the fracturing of glass?

Radial cracks appear first, starting on the side opposite the destructive force.

A piece of glass is immersed in a liquid, and it proceeds to float on the surface. This shows that the density of the glass is ______ the density of the liquid.

less than

If glass cannot be physically piece together, the control and question class or best compared by their...

Refractive index and density

Stress marks on the edge of a real crack near the point of impact area are...

Parallel to decide on which the force was applied

The most important physical properties of glass for Forensics comparison area is what?

Refractive index and density

The larger opening of a cradle shaped hole in the glass made by the penetration of a projectile indicates

The exit side of the glass

Diffraction pattern of glass usually has...

Radial and concentric lines

Refractive index measures the speed of light and a vacuum to its speed in

Any given substance

The formula for calculating the density of an object is mass per unit volume

True

The only way to analyze glass fragments at a crime scene is to assemble the fragments and physically fit them together like a jigsaw puzzle

False

Sodium carbonate and calcium dioxide or two substances that are added to silica as glass is made

False

It is possible to determine the sequence of impact by observing the existing for extra lines in their points of termination

True