Experimental Demonstration ofOptics Using Easily Obtainable
and Low Cost materials

Kiichiro Kagawa
Fukui Science Education AcademyJAPANContents of presentationI) One day workshop on optics for children(held on July 25, in Fukui by our NPO)
II) Simple direct-vision spectroscopeIII) Water lens microscope
If high school students have no experience seeing these kind ofbasic experiments, please show them. Physics should belearned through experiments, not through books!
My assertion

Chapter .1
One day workshop on optics for children

Workshop in old house(150y old)

Very dark
Wide wooden floor

Wide earthen floor

One Day Workshop for Children
Old people help this workshop
as volunteer• Contents• 1) Experiments using big smoke box• 2) Experiments using laser light• 3) Experiments using sun light (I)• 4) Experiments of reflection and dispersion• 5)Experiments using sun light (II)Spectrum• 6) Experiments of big pin-hole camera• 7) Construction of big pin-hole camera

Small smoke box
In regular workshop, we use small
smoke box and a battery lamp

Very effective to learn optics.

Just see, then understand
Small smoke box
30cm
30cm

Hard black paper

Inside is black

30cm

Battery lamp
Slit

IncentBattery lamp
Cooking wrap film

In a small smokes box

In a small smokeboxa<fConvex lensa>fFigure II.2

Batterylamp
Hardblackblackpaper
paper
Hard(Shielding plate)Figure III.3(Shielding plate)Big smoke box

Transparentplate

Size: 57 x 57 x 45 cm
Fill smoke of stick incense tosee the light ray.

Light directivity
Big smoke box
Aperture of star
shapeGroup Exp.

Point light source:
Car’s head light(12V,55W)
See the light scattering in thedirection to which light propagatesShadow
Shadow also shows the evidence of the light directivity
せんめいな影手手スクリーン

スクリーン

懐中電灯

懐中電灯

How change, when
we use light sourcewith wide area?

Image oflight
directivity

Carefully see the shadow,
Where is light source?

Enlargement using light directivity
Question for high school students
What percentage of high school
students can give right answer?

•Pulse X rayaNear point
sourceMeshd

Battery lampd'bd’ = (d x b)/ d (application of similarity)

Convex lens
凸レンズ

using Big smoke box

Convex and concave mirror
Parallel beam

for concave mirror

for convex mirror

using Big smoke box

Laser light
Directivity of laser light

Sheet beam

Glass rodIn big smoke box

In big smoke box

Application of sheet beam• 1) Draw a slight line on irregular surface• 2) Cross sectional observation of eddy

In big smoke box

Point light source made by laser light
New light source

Laser

White paper

Very simple, but important to get the conceptof laser light and ordinary lightCan see inside of bulb?

Laser

Panasonic
What percentage of high school
students can give right answer?

bulb
laser light

This Phe. relates toCoherence of laser light?

HitachiFrostedglass plate?

Attraction for children!

Jewel of diamondExperiments using sun light (I)Ask children how to know sun light isparallel beam?

Big parallel beam for optics

Drive sun light Using big mirrors

Tropical countries have muchadvantages to use sun light;
There is sun light almost every
day . (free charge)

Use as big parallel beamHome made big parallel beam
BigFresnel
lens
Diameter of 15cm

Big
FresnellensPower transformer

Head light for car:
12V, 55W (20US&)

FanWax and wane of moon
Earth science

1)Universe isdark

Optics problem2)Sun is far from earth:
Parallel beam illuminates
sphere ball3)Moon rotatesaround the earth

ウエックス、ウオン

Hemi-sphere ball

Direct demonstration to explain
wax and wane of moon
Only hemisphere is bright

Sun lightCB

Children turn aroundＡA

Suspendedballfrom A
half moonfrom B
crescent moonfrom CDemonstration of shimmer of hot air
Black and whitepatternHeat by gas lighter

きれいな平行光線

Black and white
pattern

Heated soldering iron

空気の密度の変化
光の明暗の模様ができる

We can see this
only for parallel
beam and light
ray from a point
sourceMixing process of water and alcohol
エタノールの部分

Irregular
patternが黒く見える isAlcohol
pouredinto water

Water cell

Sun light

Refraction and dispersion of light in the smoke box
paralellA little milk is added

Apex angle

Deviation
angle

verticalinclining

Water prism

Deviation angle

Two laser beam werecoincided to be one beamusing a slide glass

Glass slide

Demonstration in the big smoke boxColor dispersion in the smoke box
In the text book, but actually ,little students see!
White parallel beam

Bright point source and lensGlass prism
Water prism

White parallel beam

for glass prism

for water prism

Basic exp. can be done in the big smoke box

Color dispersion using sun light

Big water prism
Water prism

One side: 30cm
height: 25cm
Aquarium ok!

1mSpectrum of sunlight
For 90degreeFor 60degreeColor and Absorption
Sun light

Color cellophane
red cellophane1myelow cellophane

without cellophanegreen cellophane

Rainbow color due to CD gratingCDSun light

In a dark room, impressive demonstration can bemade using sun lightRainbow experiments?
Very interesting topics , but eliminated because oflack of time

Big pin-hole camera
Application of light directivity
Hole(1～3cm φ）

Usually in a small box

As dark box
Door of old house

Outside of house
Opposite image

Moving car is much better

On a screen

Home work for children
Peep
Falme of candle
consist of many
points light source

Inside of the box
Should be paintedblackCandle

ＨoleDark box madeof thick paper

In order to improve the ability of logical thinking, try to do thesebasic experiments .
Changeable conditions: hole size, number of candle, height ofcandle, distance between candle and hole, distance between hole
and white paper, number of hole, shape of the holeConstruction of big pin-hole camera
One children made one, and bring backPaint black
Old man’s lens(+ 3.0)

By digital camera

Peep

2mm φ pin-holeComparison of camera
Our type
Commercial type

＊市販の見るピンホールカメラ

Weak points

・We are forced tosee the lens- hole・image is dark.

Good point
Clear and bright image

Chapter .2Simple direct-vision spectroscope

Various types of direct-vision spectroscope

Commercial direct –vision spectroscope~ 300 US$

Simple direct-vision spectroscope

three types

1) water prism ----insufficient resolution - 95 degree prism type2) using film grating ---- a little dark3) using CD grating ---- good but one problem improved type

Water prism
Salty
waterLessresolution

Improved water prism
Apex angle: αdδWe published in Journal of Indonesia PhysicalSociety in 2003

ｄｎdn is therefractive index
difference
between red lightand blue lightAttention:
Total reflection
Control by salt
concentration

How to construct 95 degree water prism

Lengthof 75,53, 51 Glass slides
mm95 oStudent’s activity using the CD spectroscope
Every high school students should construct by themselves

Sun light spectrum:
Fraunhofer’s line
High pressure
sodium lump

Lens

NaCl

Battery lamp

Alcohol lamp

Simple exp. for Atomic
Absorption Spectroscopy

Direct vision –spectroscopeChapter .3
Water lens microscope

Water lens microscope

Screw ring
Front coverHigh magnificationof Physics
Education, 2001

Low magnification

Magnification ~10 to 40Children should repeat exp. for more thanfive hours, if cannot, no hopeEndColor of soap bubble

No fringe, no color

Fringe appear

Upper, no color

Lay a glass slide onanother, due to thesandwiched air space

Very big soap babble
Cylindricalmembrane

輪をシャボン液につけてそっと引き上げる。膜は円筒パイプになっている

表面張力が働き、底の方が縮み、ついに膜は液から離れるWave demonstrationDiffraction Pattern Using a
Caliper (Jangka Sorong)caliper

Variable Single Slitis very expensive

Razer Blades

wide single slit

narrow single slit

Dancing fringe

Lens actionof dropletsMove with time