Test 2 NewsTest 2 News

Keep your Tests in your notebook but Keep your Tests in your notebook but return your Scantron forms and the return your Scantron forms and the Manipulative.Manipulative.

Some of the questions will appear on Some of the questions will appear on the comprehensive final.the comprehensive final.

Discuss questions that you missed Discuss questions that you missed with your team mates.with your team mates.

The PlanThe Plan

Locate your name tag.Locate your name tag. Remove the team role name and Remove the team role name and

leave it on the desk in front of leave it on the desk in front of you.you.

Leave the team name sign on the Leave the team name sign on the desk as well.desk as well.

Get ready to move…Get ready to move…

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Team + Attendance

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Remember Attendance Remember Attendance SheetsSheets

Chapter 14 & Chapter 14 & 1515

Light and Light and ColorColor

““Inside My Eye”Inside My Eye”

SupplementSupplement

Parts of the Human EyeParts of the Human Eye(Supplement Handout)(Supplement Handout)

• CorneaCornea – bends light – bends light• IrisIris – controls the amount of light – controls the amount of light• PupilPupil - opening - opening• LensLens – focuses light onto retina – focuses light onto retina• RetinaRetina – back of eye – back of eye• FoveaFovea – center of your vision – center of your vision• Optic NerveOptic Nerve – “signal wire” (causes blind spot) – “signal wire” (causes blind spot)

Blind Spot Demo (Page 265)Blind Spot Demo (Page 265)

OO X X

• RodsRods - brightness receptors - brightness receptors

• ConesCones - color receptors - color receptors– Three Types: Red, Green, BlueThree Types: Red, Green, Blue

• Cones are more numerous in the center of Cones are more numerous in the center of your vision.your vision.

• Rods are more numerous around the Rods are more numerous around the periphery of your vision.periphery of your vision.

• Demo – Moving markers near peripheryDemo – Moving markers near periphery

Color DeficiencyColor Deficiency

Color VisionColor Vision Colorblindness - about 10% of populationColorblindness - about 10% of population

Red-green is predominantRed-green is predominant Yellow-blue - a fewYellow-blue - a few

What is color?What is color? Different wavelengths of light are Different wavelengths of light are

perceived as different colors. perceived as different colors.

White light contains equal amounts of White light contains equal amounts of these colors. (ROY G. BIV)these colors. (ROY G. BIV)

Fill in the BlanksFill in the Blanks

Black objects _______ all of the pure Black objects _______ all of the pure colors.colors.

White objects _______ all of the pure White objects _______ all of the pure colors.colors.

Transparent objects _______ all of the Transparent objects _______ all of the pure colors.pure colors.

absorb

reflect

transmit

Color FiltersColor Filters

Red filtersRed filters transmit red light and absorb transmit red light and absorb the other colors.the other colors.

Red objectsRed objects reflect red light and absorb reflect red light and absorb the rest.the rest.

In red light, what color do the red petals In red light, what color do the red petals and green leaves of rose appear?and green leaves of rose appear?

Color FiltersColor Filters Red filtersRed filters transmit red light and absorb the transmit red light and absorb the

other colors.other colors.

Red objectsRed objects reflect red light and absorb the reflect red light and absorb the rest.rest.

In red light, what color do the red petals and In red light, what color do the red petals and green leaves of rose appear?green leaves of rose appear?– Answers: Answers:

Petals appear redPetals appear red Leaves appear to be blackLeaves appear to be black

Color FiltersColor Filters

The following color filters are yours to The following color filters are yours to keep in the zip-lock bags:keep in the zip-lock bags:– Red, Green, BlueRed, Green, Blue– Yellow, Magenta, CyanYellow, Magenta, Cyan

FlashlightsFlashlights

All flashlights must work for this All flashlights must work for this exercise.exercise.

Mixing Colored Light Mixing Colored Light Color AdditionColor Addition

Additive Primary Colors: Additive Primary Colors: RedRed GreenGreen Blue Blue

One can produce any color by varying One can produce any color by varying amplitude and mixture or red, green amplitude and mixture or red, green and blue light.and blue light.

Color Addition Examples: Color Addition Examples:

– Tiny dots called pixels on Color TV's and Tiny dots called pixels on Color TV's and Computer Monitors are colored only red, Computer Monitors are colored only red, green, or blue.green, or blue.

– ““Color Addition”Color Addition” Lab Exercise (two pages)Lab Exercise (two pages)

– Color Addition EquationsColor Addition Equations

Remember Attendance Remember Attendance SheetsSheets(Role Rotation)(Role Rotation)

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Lab ExercisesLab Exercises

““White Light” and “Color Addition White Light” and “Color Addition Wheels”Wheels”– Everyone will color Roy G. Biv onto the 7 Everyone will color Roy G. Biv onto the 7

segment wheel.segment wheel.– XO Red + Blue = ?XO Red + Blue = ?– COCO Red + Green = ?Red + Green = ?– ENGENG Blue + Green = ?Blue + Green = ?– COM Red + Blue + Green = ?COM Red + Blue + Green = ?

Mixing Colored PigmentsMixing Colored PigmentsColor SubtractionColor Subtraction

Subtractive Primary Colors: Subtractive Primary Colors: YellowYellow MagentaMagenta Cyan Cyan

One can produce any color by varying One can produce any color by varying the amount of yellow, magenta and the amount of yellow, magenta and cyan pigments.cyan pigments.

Color Subtraction Examples: Color Subtraction Examples:

– Newspapers, magazines, booksNewspapers, magazines, books– Zip-lock with colored sealsZip-lock with colored seals

– ““Color Subtraction”Color Subtraction” Lab Exercise (two pages)Lab Exercise (two pages)

– Color Subtraction EquationsColor Subtraction Equations

Color Subtraction Color Subtraction Using CrayonsUsing Crayons

Lab ExerciseLab Exercise

ChromatographyChromatography

Lab ExerciseLab Exercise

White

Red

Green

Blue

Yellow

Cyan

Magenta

Primary Colors

Green

Pure Green

Color AdditionPrimary Green

Complementary ColorsComplementary Colors - any two colors - any two colors that add together to produce whitethat add together to produce white

e.g. magenta + green = whitee.g. magenta + green = white

Physics

Engineering

Astronomy

And our flag was still there...

SpiralSpiral

After Images and “Conal After Images and “Conal Fatigue”Fatigue”

The human eye will see The human eye will see complimentary colors after staring complimentary colors after staring at a color picture.at a color picture.

Demos:Demos: Colored ShapesColored Shapes Texas FlagTexas Flag American FlagAmerican Flag RoseRose LincolnLincoln

Lab SupplementLab Supplement

Color a Flag with Complementary Color a Flag with Complementary ColorsColors– Move this page forwardMove this page forward– What color would we use so that the What color would we use so that the

afterimage is red, white and blue?afterimage is red, white and blue?– Write this on the supplement: Write this on the supplement:

Complementary ColorsComplementary Colors Use cyan, black, and green get an after Use cyan, black, and green get an after

image that is red, white and blue.image that is red, white and blue.

Optical IllusionsOptical Illusions

Animation

Transparent and Opaque (14.2)

Transparent you can identify objects through it

Translucent you see diffuse light coming through it

Opaque you cannot see any light coming through it Opaque objects cast shadows.

“Can Light Pass Through”

Lab Exercise

“Transparency”

Lab Exercise

“Pattern for Flashlight Reflector Shield”

Lab Exercise

Why? We want a point source of light rather than a beam

when we investigate the shadows created by opaque objects.

“Tall in the Shadow”

Lab Exercise

Chapter 18Spectra

The Electromagnetic Spectrum

A range of light waves extending in wavelength from radio waves to gamma rays

The Electromagnetic

Spectrum

On Chalkboard

The Electromagnetic SpectrumRadio Waves

Microwaves

Infrared

Visible Light

Ultraviolet

X-rays

Gamma Rays

Which form of light has the …longest wavelength?…highest frequency? …highest energy?…fastest speed?

The Electromagnetic Spectrum

Radio Waves Microwaves Infrared Visible Light Ultraviolet X-rays Gamma Rays

Raging Martians Invade Roy G. Biv Using X-rays and Gamma Rays

mnemonic

Radio Waves

Microwaves

Infrared

Visible Light

Ultraviolet

X-Rays

Gamma Rays

SPFSPF

• The SPF of a sunscreen is a laboratory measure of The SPF of a sunscreen is a laboratory measure of the effectiveness of sunscreen; the higher the SPF, the effectiveness of sunscreen; the higher the SPF, the more protection a sunscreen offers against UV-the more protection a sunscreen offers against UV-B (the ultraviolet radiation that causes sunburn). B (the ultraviolet radiation that causes sunburn).

• The SPF indicates the time a person can be The SPF indicates the time a person can be exposed to sunlight before getting sunburn with a exposed to sunlight before getting sunburn with a sunscreen applied relative to the time they can be sunscreen applied relative to the time they can be exposed without sunscreen. exposed without sunscreen.

• For example, someone who would burn after 12 For example, someone who would burn after 12 minutes in the sun would expect to burn after 2 minutes in the sun would expect to burn after 2 hours (120 min) if protected by a sunscreen with hours (120 min) if protected by a sunscreen with SPF 10.SPF 10.

The Visible Spectrum

A range of light waves extending in wavelength from about 400 to 700 nanometers.

Things that create a Spectrum

Prism Raindrops CD’s Spectroscopes

Contains a Diffraction Grating

Diffraction Gratingfor Ziplock Bag

Creating a Spectroscope Roll up and tape black paper to form a tube. Cover end of the tube with foil. Use a blade to make a slit in the foil. Temporarily tape the diffraction grating over

the other end of the tube. Observe several light sources.

Incandescent Light, Florescent Light, Neon Sign

Object Names Blue Bowl Red Bowl Yellow Post-it Orange Post-it

http://sciencekit.com/

Object Names Red Filter Green Filter Yellow Filter Cyan Filter

Robert BunsenGustav Kirchhoff

“The Taste Test”versus

“The Flame Test”

Continuous Spectra Hot, dense solids produce a continuous spectrum.

(All Colors)

Hot gas produces a bright line emission spectrum.

(Bright Lines)

Emission Spectra

Filters behind continuous sources give absorption spectrum.

(Missing Colors)

Absorption Spectra

Example Questions What type of spectra do each of the following have?

Flashlight bulb Frosted Incandescent lamp Neon Sign Florescent light Red bowl

Hot Solids Hot Gasses Cool objects that reflect light

Structure of the Atom Proton Neutron Electron Energy Levels

Absorption When an electron is raised to a higher

energy level, the atom is said to be excited.

Emission When the electron returns to a lower

energy level, energy is released in the form of light.

Different transitions from high levels to low levels result in different colors of light.

Every element can be “fingerprinted” by it spectra.

“Element Fingerprinting”

Helium

Hydrogen

Oxygen

Carbon

Every element can be “fingerprinted” by it spectra.

Matching Questions

Type of Spectrum Appearance

1. Emission Spectra a. All Colors

2. Continuous Spectra b. Dark Lines

3. Absorption Spectra c. Bright Lines

Matching Questions

1. Emission Spectra a. Hot Solids

2. Continuous Spectra b. Cool Solids

3. Absorption Spectra c. Hot Gases

The color of light emitted by hot glowing solids changes with its temperature.

Glowing object colors: Reddish coolest glowing object Orange-ish Yellowish White Bluish hottest glowing object

Incandescence

Example Questions The star Sirius is blue and Arcturus is yellow.

Which is hotter? Answer: Sirius, I’m not kidding.

Consider a red filter and a blue filter. Which is hotter? Answer: They should be the same temperature

because they are not “glowing”.

Fluorescence Some materials that are excited by

ultraviolet light can emit visible light upon de-excitation. This is fluorescence.

Demo - Black light and chalk

Fluorescent Lamps Primary excitation - electron collisions with

low pressure mercury vapor, and ultraviolet light is given off

Secondary excitation - ultraviolet light is absorbed by phosphors and these emit visible light

Phosphorescence Phosphorescence - a type of light emission

that is the same as fluorescence except for a delay between excitation and de-excitation.

Electrons get "stuck" in an excited state and de-excite gradually.

Demos - glow-in-the-dark objects

Lasers Laser

Light amplification by stimulated emission of radiation

Lasers produce coherent light. Coherent light means that all the light waves

have the frequency, phase and direction. Demo - Laser and chalk dust Demo - Laser and prism or diffraction grating

Matching Questions1. Incandescence a. mercury vapor

light tubes

2. Fluorescence b. glow-in-the-dark

paints and plastics

3. Phosphorescence c. light bulbs

with filaments

Matching Questions1. Fluorescent Lamp a. color changes

with temperature

2. Incandescent Bulb b. only one color

of light

3. Laser c. converts ultraviolet light to visible light

Law of Reflection “The angle of incidence equals the angle

of reflection.”

This is true for both flat mirrors and curved mirrors. Convex Mirror - security mirror Concave Mirror - vanity mirror

Demo: Chalk Dust and Concave Mirror

Types of Reflection Specular Reflection - images seen on

smooth surfaces (e.g. plane mirrors)

Diffuse Reflection - diffuse light coming from a rough surface (cannot see a reflection of yourself)

Movie

Reflection Demonstrations Candle in Water Video (Movie)

Terminator II Movie

Supplemental Handouts Funny Face Reverse Images Make a Kaleidoscope

EGRHands-on

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Team + Attendance

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Please bring your book to class Please bring your book to class tomorrow.tomorrow.

NotebooksNotebooks

• Due on Wednesday before the Exam.Due on Wednesday before the Exam.

• http://observe.phy.sfasu.edu/http://observe.phy.sfasu.edu/courses/phy410/homework/courses/phy410/homework/NOTEBOOK.doc NOTEBOOK.doc

Principle of Least Time

Fermat's principle - light travels in straight lines and will take the path of least time

MIRROR

A B

Wrong PathTrue Path

Refraction Refraction is the bending of light when it

passes from one transparent medium to another.

This bending is caused by differences in the speed of light in the media.

WATER WAVE MOVIE

Refraction

WATER

AIR

Normal LineFast

Slow

Light Beam

Refraction Examples Light slows down when it goes from air into

water and bends toward the normal. An Analogy: A car slows down when it goes

from pavement onto gravel and turns toward the normal. MOVIE

Index of Refraction

n=c/v

Refraction

WATER

AIR

Observer

True Fish

False Fish

Lab Exercises “Refraction”

Cup of Water and Pencil Broken Pencil Movie

“Finding Object Under Water”

“Refraction Activities” Procedure 1 - Shallow Appearance Procedure 2 - Spearing a Fish Procedure 3 - Broken Images

Dispersion...…is the separation of white light

into pure colors (ROY G. BIV).

Dispersion Examples: Prisms Diffraction Gratings

Rainbows Raindrops refract, reflect and disperse

sunlight.

Rainbows will always appear opposite of the Sun in the sky.

You cannot run from or run to a rainbow!

How can you make a rainbow?

Remember Attendance Remember Attendance SheetsSheets(Role Rotation)(Role Rotation)

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Lenses Converging Lens

A lens that is thicker in the middle and refracts parallel light rays passing through to a focus.

Diverging Lens A lens that is thinner in the middle than at the

edges, causing parallel light rays to diverge.

Team Exercise: Lens sorting

Myopia (Near-Sightedness)

People with near-sightedness cannot see clearly at distance.

What kind of corrective lens will they need?

Hyperopia (Farsightedness)

People with far-sightedness cannot see clearly up close.

What kind of corrective lens will they need?

“Where is the Image?”Lab Exercise

“Making a Telescope”Lab Exercise

Total Internal Reflection... …is the total reflection of light traveling in a

medium when it strikes a surface of a less dense medium

Demo - Laser and light pipe Example: Optical Fiber Ring

Laser Underwater Movie

Woman Edge Pool Movie

WATER

AIR

Light Source

Critical Angle

Total Internal Reflection

Atmospheric Refraction Our atmosphere can bend light

and create distorted images called mirages.

http://astro.sfasu.edu/movies/Highway Mirage 1.mpg What causes stars to twinkle?

Atmospheric Turbulence

Mirage

Warm air

Cool air

Earth

Sun

Sun

Because of atmospheric refraction, we have lingering, elliptical sunsets.

Why is the sky blue?Why is the sky blue?

Nitrogen and Oxygen in our Nitrogen and Oxygen in our atmosphere atmosphere scatterscatter high high frequencies of light.frequencies of light.

Why are sunsets Why are sunsets red?red? Red light is scattered the least by our Red light is scattered the least by our

atmosphere. atmosphere.

The greatest path of sunlight through The greatest path of sunlight through the atmosphere is at sunset or the atmosphere is at sunset or sunrise.sunrise.

Why are clouds Why are clouds white?white?

The color of light scattered by clusters of The color of light scattered by clusters of water molecules vary with the size of the water molecules vary with the size of the clusters.clusters.

The size of clusters of water molecules The size of clusters of water molecules (droplets) vary in clouds.(droplets) vary in clouds.

Why is the ocean Why is the ocean greenish blue?greenish blue? Red light is absorbed by the Red light is absorbed by the

molecules in the water.molecules in the water.

Review for Test 3Review for Test 3

Chapter 14Chapter 14– ColorColor

Chapter 15Chapter 15– RefractionRefraction

Chapter 18Chapter 18– SpectraSpectra

Chapter 14Chapter 14 Section 14.3 through 14.8Section 14.3 through 14.8

– Selective ReflectionSelective Reflection– Selective TransmissionSelective Transmission– Color AdditionColor Addition– Color SubtractionColor Subtraction– Complementary ColorsComplementary Colors– Conal FatigueConal Fatigue– Why is the sky blue?Why is the sky blue?– Why Sunsets are RedWhy Sunsets are Red

Chapter 15Chapter 15 Section 15.2 through 15.6Section 15.2 through 15.6

– Refraction - BendingRefraction - Bending– Speed in different mediaSpeed in different media– Apparent Water DepthApparent Water Depth– Illusions and MiragesIllusions and Mirages– Atmospheric RefractionAtmospheric Refraction– DispersionDispersion– RainbowsRainbows– Lenses and TelescopesLenses and Telescopes– Your EyeYour Eye– Image FormationImage Formation

ExercisesExercises Bob the Builder and Filter GlassesBob the Builder and Filter Glasses ““Goggles” - SupplementGoggles” - Supplement ““Kaleidoscope”Kaleidoscope” ““Animal Shadow”Animal Shadow” ““Prism Power”Prism Power” ChromatographyChromatography

Diffraction a modification which light undergoes in

passing by the edges of bodies or through narrow slits

…and in which the rays appear to be deflected and to produce fringes of parallel light and dark or colored bands

Water Wave Interference Movie

Multiple Slit Interference Movie

Doppler Effect the change in wavelength due to motion of

the source or observer

"Wheeeeeeeeeeee…….Oooooooooooooo”

Examples: Water, Sound, and Light

Source at Rest

Wavelength

What happens when the source in in motion?

Movie #1Movie #1

Java

Source in Motion

Short Wavelength

High Frequency

High Pitch

Weeeeeeeee!!!

Long Wavelength

Low Frequency

Low Pitch

Ooooooo!!!

As a team, describe what happens to the wavelength, frequency, and pitch both in front of and behind a moving sound source.

Doppler Effect Examples:

moving cars and trains Sound Movie #2

moving buzzer in a nerf ball (in class)

Chapter 14 & Chapter 14 & 1515

Light and ColorLight and Color

Be prepared to turn in your notebook at the beginning of Test 3.Be prepared to turn in your notebook at the beginning of Test 3.It will be returned at the end of Test 3.It will be returned at the end of Test 3.

Please keep your notebook after that for your future class.Please keep your notebook after that for your future class.

Test 3 Test 3

• Everyone starts Test 3 at 1pm.Everyone starts Test 3 at 1pm.

• Manipulative Manipulative – Transparent, Translucent, OpaqueTransparent, Translucent, Opaque– Spectra, Color, and LensesSpectra, Color, and Lenses– Pendulum (Optional)Pendulum (Optional)

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Remember Attendance Remember Attendance SheetsSheets

Remember Attendance Remember Attendance SheetsSheetsYour view…Your view…

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Chapter 14 & 15Chapter 14 & 15Light and ColorLight and Color

Remember Attendance Remember Attendance SheetsSheets(Role Rotation)(Role Rotation)

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Remember Attendance Remember Attendance SheetsSheets(Role Rotation)(Role Rotation)

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Remember Attendance Remember Attendance SheetsSheets(Role Rotation)(Role Rotation)

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