LIGHTLIGHT

M A PM A P ssMeaningful Applications of Physical ScienceEmail: MAP@ScienceScene.com

LIGHTLIGHT . .

LIGHTLIGHT

A. Properties of light

B. Absorption

C. Reflection

D. Refraction

E. Application of the Properties of Light

LIGHTLIGHT

A. Properties Of Light

1. How Is A Radiometer Affected By Light? . . . . . . . . . . . . . . . . . 7

2. Speed Of Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3. The Role Of Light In Seeing . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4. The Affect Of A Pinhole On Light . . . . . . . . . . . . . . . . . . . . . . . 12 5. Properties Of Shadows . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 16

6. Representing The Behavior Of Light By Drawing Light Rays . . 25

7. A Model Of Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 A. What Is A Pulse? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 B. What Are The Properties Of Pulses? . . . . . . . . . . . . . . . . . . 29 C. Light As Waves – Electromagnetic Radiation . . . . . . . . . . . 35 D. Interference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

LIGHTLIGHT

B. Absorption

1. Absorption Of Light Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

2. Absorption Of Light Energy and the Greenhouse Effect . . . . . . . . . . 46

LIGHTLIGHT

C. Reflection1. How Do Things Appear In A Mirror? (Palindromes) . . . . . . 50

2. How Much Of Yourself Can You See In A Mirror? . . . . . . . . . 56

3. Where Is The Mirror Image? (Single Burning Candle, Double Burning Candle) . . . 61

4. How Does Light Reflect? (The Law) . . . . . . . . . . . . . . . . . . 65Building The Ray Maker, Three Mirrors, Classroom Reflection

Pin Reflection Game, Two Handled Mirror - Three Hands?

Aquarium - Count The Strings

Barber Pole Effect, Peppers Box, Infinity Box

5. How Does Light Reflect From A Non-shiny Surface? . . . . . . 71

6. How Do Curved Mirrors Reflect Light? . . . . . . . . . . . . . . . . . 76Concave Mirror and The Inverted Light bulb

Circus Mirrors, Mirage (pick up the object)

LIGHTLIGHT

D. Refraction

1. Transparent, Translucent And Opaque Objects . . . . . . . . . . . . . 81

2. How Does Light Change Direction When Refracted? . . . . . . . . 82

Ghost Crystals, Oil Immersion Oil, Plastic Rod, Pepsi Bottle Refraction

3. Laws Of Refraction (Plastic Block) . . . . . . . . . . . . . . . . . . . . . . 88

4. Seeing Objects Through Transparent Materials? (Aquarium). . . . . 93

5. Spear Fishing, Mirages And Twinkling Stars . . . . . . . . . . . . . . 99

6. Lenses - Magnifying Lens For Image Production (Pin Hole Camera Extension)

A. Types Of Lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107B. Power And Focal Length . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

C. Eye Defects - Nearsightedness And Farsightedness . . . . . 123D. How To Make A Telescope . . . . . . . . . . . . . . . . . . . . . . . . . 125

LIGHTLIGHT

E. Application of the Properties of Light

1. Dark Suckers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

2. Transmitted Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132Coiled Plastic Rod, Critical Angle demonstration, Fiber optics,

Transmission of Sound by Modulation of Light Energy

3. Polarized light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

We Had A Great Time

1. Light is associated only with either a source or its effects. Light is not considered to exist independently in space; and hence, light is not conceived of as “traveling”.

2. The effects of light are instantaneous. Light does not travel with a finite speed.

3. An object is “seen” because light shines on it. Light is a necessary condition for seeing an object, but there is no recognition of anything that moves between the object and the eye.

4. Lines drawn outward from a light bulb in a sketch represent the “glow” surrounding the bulb.

5. A shadow is something that exists on its own. Light pushes the shadow away from the object to the wall or ground and is thought of as a “dark” reflection of the object

6. Light is not necessarily conserved. It may disappear or be intensified.

7. Light from a bulb only extends outward a certain distance, arc then stops. How far it extends depends on the brightness of the bulb.

Naïve Ideas - Properties of light

7

How is a Radiometer Affected by Light?

A radiometer consists of a set of vanes, each shiny on one side and blackened on the other, that is mounted in an evacuated vessel. When exposed to light, the vanes revolve. The first radiometer was constructed to settle the controversy regarding whether light exerts a force. The idea was that a reflecting surface would experience a greater force from the light than an absorbing one. Unexpectedly, the opposite effect was observed. The blackened vane retreated from the light source. We now know that the black surface is warmer than the shiny one and that gas molecules will recoil faster from the hot surface. The slight difference in molecule recoil is what causes the device to spin.

Speed Of Light Compared to the Speed of Sound

1

Light: 3 x 108 meters per second or 186,000 miles per second

Sound: 330 meters per second or 1100 feet per second.

BANG!

See The Book

1

Spreading Light

0

2

The affect of a pinhole on light

3

1

Pinhole Image

0

I. Characteristics Of A Wave

A. Pulse: a single disturbance in a medium.

B. Frequency: the number of occurrences of some event per unit of

time.

(example; the number of times the meter stick goes up and down in one minute.)

C. Amplitude: the measurement of the distance the medium moves from

the

zero point to the maximum displacement. (example; the distance of the

very end of the meter stick - from standing still to the farthest distance away from

that zero position.)

D. Wavelength: the distance along a wave front — from any starting

point

to the next successive starting point. (example; looking at a slinky in motion.

Begin with the very beginning of a pulse to the very beginning of the next pulse.)

E. Loudness: occurs with the addition of energy to the vibrating

medium.

Characteristics Of Waves

Wavelength

Period = .5-sec.

Time = 1 sec

Frequency = 2 Hz

Amplitude

Five Basic Characteristics of Waves

1. Wavelength (l), is the distance from a point on a wave to the next point

2. Amplitude (A), is the maximum displacement. Amplitude indicates the loudness of a sound.

3. Period (t), is the time (in seconds) that it takes for a wave to travel one full wavelength.

4. Frequency (f), is the number of vibrations (waves) per second. This indicates the pitch of a sound.

5. Wave speed (V), is the rate the wave is traveling; the units of measurement are meters/sec. 9

FUNdamentals of Waves

II. Components Of Light and Sound waves

A Energy is needed to form any Light or Sound wave.

B Light waves are made by continuous succession of oscillating magnetic and

electric fields. These fields travel as a wave, an EM (Electromagnetic) wave.

C. Sound waves are made by the vibrations (moving back and forth) of

the particles of an object.

D. A medium is NOT needed to transport the Light energy.

E. A medium is needed to transport the Sound energy.

F. Waves are formed when energy is transported from one place to another.

8

FUNdamentals of Waves

III. Three Types Of WavesA. Torsional waves when the disturbance occurs as a twisting effect in a plane that is perpendicular to the direction on the wave motion (examples: twisters, hurricanes, tornados).

B. Longitudinal waves when the disturbance occurs in the same direction of the wave motion. (examples: sound, people standing in line, cars taking off from one red light and coming to a stop at another red light.)

C. Transversal waves when the disturbance occurs at right angles to the direction of the wave motion. (examples: water, light, radio, electromagnetic.)

7

Building a Wave Model

6

Wave Patterns

http://www.explorelearning.com/index.cfm?method=cResource.dspView&ResourceID=28

35

4

Propagation of Light Energy

3

Wave Properties

2

Construction & Destructive Interference

Constructive Interference

Destructive Interference 1

EM Spectrum

0

Shadows

Object

Object Shadow

Shadow

Illumination

Illumination

Illumination

Illumination

Screen

Bulb

Bulb

3

1

Multiple Shadows

Object FullShadow

FullIllumination

Screen

Bulb

Bulb

PartialShadow

PartialShadow

FullIllumination

0

1

Absorption of Light Energy

Absorption of Energy and the Greenhouse Effect

Naïve Ideas - Reflection

1. A mirror reverses everything.

2. For an observer to see an object it must be directly in front of the mirror.

3. The position of the observer is not important in determining whether the mirror

image can be seen.

4. An observer can see more of his or her mirror image by moving further back from

the mirror.

5. The mirror image of an object is located on the surface of the mirror. The image

is thought of as a picture on a flat surface.

6. A mirror’s image goes from the object to the mirror’s surface. The observer sees

the image on the mirror surface which is reflected off the mirror.

7. Light reflects from a shiny surface in an random manner.

8. Light is reflected from smooth surface mirrors but not from non-shiny surfaces.

9. Curved mirrors make everything distorted.

9

PalindromesWords and numbers that read the same forward as backward.

1

Some Palindromes have symmetry. When a mirror is

placed on the right, of the word, and perpendicular to

the surface the word is read the same in the mirror as

without the mirror.

Palindromes

MOM

RACECAR.

EVIL OLIVE.

STEP ON NO PETS

RISE TO VOTE, SIR

DO GEESE SEE GOD?

NEVER ODD OR EVEN.

A DOG! A PANIC IN A PAGODA!

A MAN, A PLAN, A CANAL -- PANAMA!

DRAW, O CAESAR! ERASE A COWARD!

NO, SIR, PANIC IS A BASIC IN A PRISON.

GO HANG A SALAMI. I'M A LASAGNA HOG.

STRESSED? NO TIPS ? SPIT ON DESSERTS.

ARE WE NOT DRAWN ONWARD, WE FEW? DRAWN ONWARD TO NEW ERA?

DOC, NOTE. I DISSENT. A FAST NEVER PREVENTS A FATNESS. I DIET ON COD

0

Mirror Image

2

Single Candle Reflection

A single piece of plastic is held in a vertical position by two support blocks.When viewing from the position of the lit candle the reflection, of the lit candle, makes the unlit candle, on the other side of the plastic, look lit.

1

Double Candle Reflection

Two pieces of

plastic are held in a

vertical position by

two support blocks.

When viewing from

the position of the

lit candle the two

reflections, one for

each piece of

plastic makes the

unlit candles, on

the other side of

the plastic, look lit.

0

How Much of Yourself Can You See in a Mirror?

Two Questions:

1. How tall, compared to his actual height, is the man’s image in the mirror?

2. If the man mover two meters further from the mirror what will happen to his image?

Mirror

51

How Much of Yourself Can You See in a Mirror?

Two Questions:

1. How tall, compared to his actual height, is the man’s image in the mirror?

2. If the man mover two meters further from the mirror what will happen to his image?

Mirror

5

165.0-cm

180.0-cm

a

a

b

b

82.5-cm

90.0-cm

7.5-cm

0

Making Rays of light

5

Making Rays of light

4

Investigating The Law of Reflection

3

The Reflection Game

Midpoint

Normal

Place a pin at the point labeled midpoint. This will hold the mirror in a vertical position to the cardboard and be used as a reference point. Looking at the protractor select any number along the outside and place the second pin at that point. Hold the cardboard at eye level. Move the cardboard until you discover the position that you can see the first and second pins lined up in the mirror. When the two pins appear to be lined up in the mirror adjust the third pin so that all three pins appear to be in a straight line and insert it into the cardboard at that point. Compare the number, on the protractor, of the first pin to the third pin.

2

Law of Reflection

Reflecting Surface

Incoming

Ray Of Light

Normal

Outgoing

Ray Of Light

41

Law of Reflection

REFLECTIVE

SURFACE

Incident Ray

Reflected Ray

Normal

A reference line drawn

perpendicular to the surface at

the point the light ray strikes

Angle of

Incidence

Angle of

reflection

Angle of Incident = Angle of Reflection4

Simulator the Light Laboratory

0

How does light reflect from a non-shiny surface? Regular & Diffuse Reflection

Regular Reflection

Diffuse Reflection

How Do Curved Mirrors Reflect Light?

33

How Do Curved Mirrors Reflect Light?

Concave Mirror Convex Mirror

2

How Do Curved Mirrors Reflect Light?Using a Simulator

1

How Do Curved Mirrors Reflect Light? Using a Simulator

0

Naïve Ideas - Refraction

1. Light shines on a translucent material and illuminates it so that it can be

seen. Light does not travel from the material to the eye.

2. Light always passes straight through a transparent material without

changing direction.

3. When an object is viewed through a transparent solid or liquid material,

the object is seen exactly where it is located.

3

Transparent, Translucent & Opaque

Transparent

Translucent

Opaque

3

How Does Light Change Directions?Refraction

Light Ray

Light Ray

Light Ray

Transparent Material

Transparent Material

Transparent Material

Refracted Light Ray

Refracted Light Ray

3

Refraction Through A Block

2

Refraction Summary

AirAir – Less Dense

Air

Air

Light Ray

3

2

Normal

Glass – More Dense

In the drawing air has less optical density than glass. The light ray is passing from a medium of lesser optical density to one of greater optical density. The light ray will bend towards the normal.

1. Determine the position of the normal.

To determine how a ray of light is refracted as it passes from one optical medium to a different optical medium follow these three steps.

1

2. Determine where the ray of light would have gone if the medium through which the light passed had not changed.

3. Determine whether the ray is bent away from, or towards the normal. (Greater density toward the normal, lesser density away from the normal)

13

A How Does Light Change Directions? Party Trick Based on the Refraction of Light

Explain that just as a glass prism splits up the different colors of white light, when different colored light passes through glass; it is also affected to an extent that depends on its color. Write the words CARBON DIOXIDE on a piece of paper, CARBON in red and DIOXIDE in blue. Put the paper close behind the stem of a wine glass, and look at the words through the stem. The red letters turn upside down, but the blue ones don't.

This has nothing to do with the different colors of the words, or of red light being bent more or less than blue light. The stem of the wine glass turns both words upside down, but because DIOXIDE is symmetrical about a horizontal line, you don't notice that it is upside down - it looks just the same either way. Try the words CHOICE QUALITY.

0

CARBON DIOXIDE

1

Refraction Analyzed

Incomming Ray of Light

Normal

Air

Water

Air

Air

Water

7

1

Measuring Index of Refraction

Incoming Ray of LightNormal

Refracted Ray

of Light

Where the light Ray o

would have gone if it was

not refracted

Water

Air

0

Seeing Objects Through Transparent Objects Refraction - Appearing Coin

3

Seeing Objects Through Transparent Objects The Distorted Straw

Apparent Position

Actual Position

2

Seeing Objects Through Transparent ObjectsRefraction Through a Block

Side View

Actual Pencil

Plexiglas

Block

Virtual image of

Pencil as seen

through the block

1

Seeing Objects Through Transparent Objects

Sight Here to See The Coin

Aim Here to Hit The Coin

Air

Water

Apparent Direction

To the CoinActual Position

of the Coin0

Where Do You Aim

1

Road Mirage

Observer

Mirage

Light From Sky

0

Types of Lenses

Converging Lenses Diverging Lenses

6

Investigating Convex Lenses Simulator

5

Image Formation With a Converging Lens Simulator

4 4

Seeing the Image

3

Image Formation With a Diverging Lens Simulator

21

Investigating Concave Lenses Simulator

1

Diverging Lens Increases the field

Field of

View

Field of

View

Without Diverging Lens

With Diverging Lens

0

Power & Focal Length

Higher

Power

Lower Power

Shorter Focal Length

Longer Focal Length

The lens strength in diopters

is defined as S = 1/f (meters).

Note: Converging lenses are

+ and diverging lenses as - .

What is the diopter number of

a lens of focal length 0.05

meters? S = 1 / 0.05 = 20

What is the focal length of a

+7 diopter lens?S = 1 / f

f x S = 1

f = 1 / S = 1 / 7 = .143-m

Normal Eye

4

Farsighted Eye

3

Nearsighted Eye

2

Nearsighted Eye

Diverging Corrective Lens

Nearsighted Eye

1

Farsighted Eye

Converging Corrective Lens

Farsighted Eye

0

How to make a telescope

Simulator - The Light Laboratory1 2

How to make a telescope Simulator

1

Telescopes

Astronomical Telescope

Galilean Telescope0

DarkSucker

s

The light beam stays internal to the water,

continuously reflecting at each boundary.

Transmitted Light - Total Internal Reflection

3

Transmitted Light - Total Internal Reflection

2

Transmitted Light - Coiled Plastic Rod

11

Transmission of Sound Through The Modulation of Light

400 – Turn Coil

Wrapped on

Bolt

470 – Ohm

Resistor

9-volt

Battery

Radio or

Tape Recorder

Amplified

Speaker

Solar

Cell

LED

0

Transmitted Light - Polarized Light

We Had A Great Time