 Refraction = the bending of a light wave as it passes from one medium to another  Refractive Index (RI)= a comparison of the speed of light in a vacuum.

Slides:

Advertisements

Similar presentations

Refraction of light.

Advertisements

Many solids are crystals A solid in which the atoms are arranged in a regular pattern Sodium chloride.

Trace Evidence Continued.... I. Glass Introduction A. = a common type of trace evidence B. Characteristics of glass 1. Common material in our environment.

Chapter 14 Glass “There is no den in the wide world to hide a rogue. Commit a crime and the earth is made of glass.” —Ralph Waldo Emerson.

Velocity of light in medium Velocity of light in vacuum R.I. = FACTS:

Refraction of an EM Wave n air = n water =1.33 Index of refraction n = c/v Direction of propagation bends toward the normal axis going from 1 medium.

Glass a “chip” off the old block. What is glass? Mixture of: –Sand –Soda –Lime –Other trace elements.

Glass Fragment Identification. Copyright © 2013 Crosscutting Concepts, LLC. All Rights Reserved. Scientific Working Group.

Physics. PHS 5041 Optics Refraction of Light Refraction always occurs simultaneously with some partial reflection Change in direction is with respect.

Light by Rifki Irawan Refraction. Based on how the light behaves as it encounters a substance, substances can be classified into: Transparent substance.

1. What types of forensic evidence do you think can be gathered from glass? 2. What types of forensic evidence do you think can be gathered from soil?

Forensic Glass Analysis. Characteristics of Glass Hard, amorphous solid Usually transparent Primarily composed of silica, with various amounts of elemental.

1.What is ‘α’ called? 2.What is ‘β’ called? 3.Define the term ‘refraction’ 4.α = 42 o, β = 30 o, v 1 = 7ms -1 and λ 1 = 2m. Using Snell’s law, calculate:

Glass Analysis Part 2 Mrs. Ashley.

Composition of Sand at Sandy Hook. What is Refractive Index? Refractive Index (RI) is the ratio of the speed of light in a vacuum compared to the speed.

Glass as Evidence. Unit Overview Most often the composition of glass is unique and therefore identifiable.Most often the composition of glass is unique.

Glass Quiz 10/27/2014.

Chapter 14 Glass “There is no den in the wide world to hide a rogue. Commit a crime and the earth is made of glass.” —Ralph Waldo Emerson.

Test: Friday Oct. 7 *properties of matter *density *properties of light *fracture patterns.

Reflection and Refraction 1. Reflection Reflection is when light hits a boundary and bounces off The law of reflection states that the angle of incidence.

Explain how glass is formed List some of the characteristics of glass

Vocabulary Concentric Fractures Radial Fractures Refractive Index

REFRACTION. What is Refraction?  Refraction is the bending of light rays as they travel from one medium to another.  Medium – a material that is part.

Glass Evidence. Automobile Accidents Automobile Accidents – Windshield, head lamps Store Break-in Store Break-in – Window glass with trace evidence Suspect.

PHYSICAL PROPERTIES GLASS

Unit 2C Glass & Soil Evidence. Forensic Analysis of Glass Glass that is broken and shattered into fragments during the commission of a crime can be used.

What is the state of matter of glass at room temperature?

Chapter 14 Section 1: refraction.

Properties of Matter and the Analysis of Glass

Refraction and Snell’s Law Refraction: bending of light at the interface of 2 different materials.

In a vacuum (void of molecules), light travels at 3.0 x 10 8 m/s, Light travels at different speeds in different materials or mediums. while in water.

Refraction (Slowing Down) When a wave passes into a medium that makes it slow down, the wave will bend toward the normal Air Water.

Analysis of Glass. Glass As Evidence What types of information can scientists learn from broken glass evidence? Glass fragments can be identified by glass.

Sun dogs, or mock suns, are technically called solar parhelia (parhelia meaning "with the sun") and appear as bright bursts of light formed when sunlight.

Chapter 4: Properties of Matter and the Analysis of Glass

Glass as Evidence. Properties The composition of glass is unique and therefore identifiable. The composition of glass is unique and therefore identifiable.

When light travels from one material to another it usually changes direction The bending of light that occurs at the borderline of two materials is called.

{ Refraction The bending or change in direction of light when it travels from one medium into another.

Have you ever wondered why a straw appears to be disconnected when placed in water?

Okobu! Do Now: – Take out Notes and prepare for Quiz Agenda: – Review of Density techniques – Refractive Index HW: – Ch 4 #3,5,7-10,19-22,28-35 due 11/1.

REFRACTION Physics Chapter 18b. Refraction Bending rays of light as it passes from one medium to another Caused by change in speed of wave Amount of refraction.

Refraction. Refraction of Light When light waves pass from one medium to the next, its speed changes, causing it to bend. Going from lower to higher index.

Refraction and Lenses. Objectives Recognize situations in which refraction will occur. Identify which direction light will bend when it passes from one.

Kendall/Hunt Publishing Company

Explain how glass is formed List some of the characteristics of glass

Types of Glass Saferstein - Chapter 4.

Glass and Light “There is no den in the wide world to hide a rogue. Commit a crime and the earth is made of glass.” —Ralph Waldo Emerson.

Properties and Analysis

Unit 2C Glass & Soil Evidence

Chapter 14 Glass “There is no den in the wide world to hide a rogue. Commit a crime and the earth is made of glass.” —Ralph Waldo Emerson.

Glass as Evidence.

Explain how glass is formed List some of the characteristics of glass

Explain how glass is formed List some of the characteristics of glass

Chapter 15 Refraction.

Lesson 17 Key Concepts and Notes

Refraction of light.

Index of Refraction.

Index of Refraction n = index of refraction c = speed of light in a vacuum (3.00 x 108 m/s) v = speed of light in other medium.

Glass & Soil Evidence.

Plane Mirror – Reflection

Forensic Glass Analysis

Explain how glass is formed List some of the characteristics of glass

Refraction Notes 5/13/15.

Refraction The bending or change in direction of light when it travels from one medium into another.

REFRACTION OF LIGHT.

PHYSICAL PROPERTIES GLASS

Presentation transcript:

 Refraction = the bending of a light wave as it passes from one medium to another  Refractive Index (RI)= a comparison of the speed of light in a vacuum to the speed of light in another substance  Sample calculation: speed of light in vacuum is 3.00 x and the speed of light in water is 2.25 x  Thus RI of water 3.00 x = ________________ = x 10 10

 Different types of glass will have different RI  To analyze this property  Glass fragments can be immersed in a liquid with a known refractive index to help approximate the RI of the evidence

 If the liquid has the same RI as the glass sample, the glass will disappear under a microscope.  If the liquid has a higher or lower RI, the glass is visible and a “halo” appears around perimeter (we call this halo the “Becke Line.”) ... when RIs are the same, the Becke line disappears ... if Becke line appears on the outside perimeter = Glass has lower refractive index ... if Becke line appears on inside perimeter = Glass has higher refractive index

InsideDisappearsOutside **GOAL**

 Glass has lower refractive index

 Glass has higher refractive index

LiquidRefractive index Ethyl acetate1.373 n-butyl alcohol1.402 Olive oil1.467 Corn oil1.473 Castor oil1.482 Methyl salicylate1.522 Clove oil1.543 Canola oil