Download Glass

Many solids are
crystals
A solid in which the atoms are arranged in a
regular pattern
Sodium chloride
Glass is an amorphous solid.
A solid in which
the atoms are
in no order. It is
also brittle and
shows a
conchoidal
fracture
pattern, has
hardness, and
elasticity of
shape.
Types of Glass
a. Soda-lime glass
most common commercial glass
(90% of total production)
least expensive
Soda-lime glass is used for:
b. Borosilicate glass
• strong
• heat resistant
• contains boron oxides
c. Tempered Glass
made stronger than soda-lime glass by
rapid heating and cooling; used for side
and rear windows in cars
Also used in…
Tempered glass breaks into….
d. Laminated glass
For windshields
e. Soda-lead glass
• commonly called crystal or
lead glass,
• expensive
• widely used for the finest
tableware and art objects.
Comparison
a. Individual evidence (jigsaw fit)
b. Class characteristics
1. Flotation
Used to find the density of glass by floating glass
particles in liquids of known densities.
Density
Mass per unit of volume
Density = Mass/Volume
2. Immersion method – used to find the
Refractive Index of glass
Refractive index (RI)
Formula RI = velocity of light in vacuum
velocity of light in medium
The RI of water at room
temperature is 1.333
MATCH POINT The point at which the
Becke line disappears
When the Becke line disappears
The RI of the glass = RI of the oil
© Hot Stage
microscope
Heats the
Immersion oil
(changes
the RI of
the oil)
GRIM 2
Annealing
• Slowly heating & cooling of
glass
• Makes glass more durable
Data bank
• Densities
• Refractive indices
• Relative
frequencies
in the glass
pop of US
Fragments
a. Types
(1) Radial fractures
(2) Concentric fractures
b. First Fractures
• Form on the side
of the glass
OPPOSITE
the side of the
penetrating
object
• Radial fractures
c. Next Fracture
• Forms on the SAME
side of the glass as
the penetrating force
• Forms concentric
fractures
d. Stress markings
3 R Rule
Radial cracks form a Right angle on the
Reverse side of the force
Fracture Termination
Which bullet hole was made first?
Also know…
Blowback; the backscattering of
particles toward the direction of the
force.
A high-velocity projectile leaves a wider
hole on the exit side of the glass