Light Touch

Sunsets & Rainbows—Experiments for Kids Imagine the w o r l d w i thout l ight. This place w o u l d probably be pretty bor­ing. In fact, noth ing m u c h w o u l d be here at a l l . L igh t is not on ly the rea­son for l i fe on Ear th , but it is our ma in source of in format ion about our wo r l d and the universe. The on ly extraterrestr ia l b o d y that w e h a v e a c t u a l l y touched has been the moon , and that d idn ' t happen u n ­t i l 1969. L ight and the phe­nomena that s u r r o u n d it creep into our l ives every d a y , r a i s i n g a l l sor ts of " d u m b " q u e s t i o n s , l i k e " W h y is the sky b lue? " or " W h y is a sunset red?" or "Wha t is a ra inbow, any­w a y ? " M a n y ch i ld ren are prone to ask questions l ike these, and that 's a green l ight to learn about optics! Here are a couple of ideas that might get their atten­t ion.

M A K I N G A S U N S E T IN A

G L A S S O F W A T E R

To set this up , y o u w i l l need a tal l , clear glass of water, 1/2 teaspoon of m i l k , and a flashl ight. M i x the m i l k into the glass of water and turn off the l ights so that the r o o m is dark . Sh ine the flashl ight through the side of the glass and notice the b lu ish color of the water-mi lk mixture. N o w , ho ld the f lashl ight under the glass and look at the bulb through the water. The bu lb shou ld appear to be an orange-red color. Exper iment w i t h dif­ferent amounts of m i l k and different levels of water.

Here 's w h y it wo rks :

JOSH COBB is an optical systems engi­neer/lens designer with IBM's Optical Development Services, Poughkeepsie, N.Y., and co-author of L igh t Ac t i on , a children's book on optics.

The Eng l i sh physic is t L o r d John W.S. Ray le igh , w h o l i ved f rom 1842-1919, d iscovered the pr inc ip le beh ind this phenomenon that creates blue skies and r ich , red sunsets. W h e n a wave of l ight is in terrupted by a t iny par­

ticle that is smal ler than its wave­length, part of the l ight is scattered. This happens because the part ic le is too smal l to reflect any of the l ight, so the l ight diffracts a round it. A smal l part icle w i l l scatter short wavelengths of l ight (the blue end of the spectrum)

more than long wavelengths (the red end of the spectrum). A s the l ight trav­els through the l i qu id it meets up w i th smal l fat part ic les suspended i n the water. The blue l ight is scattered and l ights up the l i qu i d to g ive it a b lu ish

hue. W h e n the l ight trav­e ls t h r o u g h a l a rge amount of the l i qu id most of the blue and green l ight is dep le ted . W h e n y o u look at the bulb through a l l of that l i qu id most of the l igh t that makes it f rom the bu lb to your eye has longer wavelengths, so the bu lb appears to be red.

The a tmosphere is f i l led w i t h t iny part icles of dust , water, and gas molecules. These scatter the b lue l ight f r om the sun, g i v ing the sky a blue appearance. A s the sun starts to set it is lower i n the sky and goes through more of the atmosphere. M o r e of the b lue, green, and ye l low l ight is scat­tered off, leav ing the sun a deep orange color.

S U N G L A S S E S T H A T

E R A S E R A I N B O W S

To set this up , y o u w i l l need a pair of po la r i zed s u n g l a s s e s , a g a r d e n hose, and a sunny day. Stand w i t h your back to the sun and use the gar­den hose to spray a fine mist of water into the air. W h e n y o u see a ra inbow, put on the sunglasses. Ti l t your head f rom side to s ide as y o u w a t c h the ra inbow. Y o u shou ld see

parts of it d isappear and reappear as y o u ti lt your head.

Here 's w h y it works : W h e n the sunl ight enters a droplet of water, the different wavelengths are refracted by

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56 OPTICS & PHOTONICS N E W S / M A R C H 1994

How-To

Affecting Positive Change with Subcontractors In any complex manufacturing pro­cess, the end product depends greatly on the efforts of various subcontrac­tors who have distinct areas of exper­tise. The main contracting house performs integration of the subcon­tracted items and end item testing. For the end item to perform as adver­tised, the subcontractor must be viewed not only as a critical team member, but also as a peer. A compli­cated project wi l l only succeed as long as the value and importance of the subcontractor is acknowledged.

As a subcontract manager for a large aerospace firm, I have had many opportunities to witness and partici­pate in both bad and good subcon­tract administration. In many cases, the differences were purely on a per­sonal, not a product, basis. This does not imply that personnel changes would fix problems on a consistent basis; sometimes the "personnel" problem reaches deeply into a corpo­rate history and no amount of change in personnel wi l l affect performance. What must be changed are attitudes and perceptions.

In this article I would like to ad­dress three related areas that I be­lieve wi l l affect change in a positive manner. These observations are based on 21 years of dealing with subcon­tractors from both small and large companies. Although the size may differ from company to company, I believe that the application of the fol­lowing concepts wi l l have an overall positive impact on the delivery of a value-added product.

WIN-WIN

Much has been written about "win-win." Win-win is a concept that is currently in vogue, but is not gener­ally understood. The key is in the self-explanatory definition. Win-win does not mean "I win—you lose—I look good." Too many times we work to­

gether as a team during a proposal preparation, but upon contract award, the partners become adversaries. The honeymoon is over when profit is on the line. For win-win to be effective, both parties must be wil l ing to give and take to achieve the best possible solution. During the early proposal preparation, both sides must be up front and candid with each other. Can­did discussions that are held early in the procurement process can identify and resolve issues that, if left unat­tended, wi l l come back to haunt both sides. Win-win can and does work if it is actively pursued by all affected parties.

T R U S T

A corollary to win-win must be trust. To perform as a team, trust must be established on both sides. Each com­pany must keep to its strategic agen­das to achieve their overall goals, but it is possible to meet your goals and trust someone else at the same time. Given competitive environments and shrinking budgets, trust is not easy to establish or maintain. However, these are the very reasons that trust must be an objective in any enterprise that wishes to succeed. Trust is gained slowly and lost quickly, so the gain­ing and maintaining of trust must be­come an everyday, ongoing way of doing business. Subcontracting is dif­ficult; if trust does not exist, the task can become impossible.

C R E D I T

When a business relationship goes badly, there is no lack of blame to spread to anyone associated with the effort. On the other hand, when an effort goes as planned and is viewed as a glorious success, the tendency is to personalize the success. Too often the main, or Prime Level, contractors see themselves as omnipotent givers of direction who would always suc­ceed if subcontractors would only fol­low directions. This phenomenon of sharing the grief and taking the glory is not unique to business relation­ships. It is a basic human trait that we

all like things that make us look good while we distance ourselves as rap­idly as possible from actions that put us in a bad light. While I cannot change human nature, I do actively try to share the good and the bad with my suppliers. I have found that, if credit for a job well done is recog­nized quickly, a by-product wi l l be the element of trust mentioned above.

C O N C L U S I O N

This is all intended to point out that common courtesy and personal integ­rity are not only necessary when deal­ing with people, but also required when dealing with institutions. To be successful, we must all work to de­liver the highest quality at the lowest cost. By treating subcontractors as members of the product team, cost and quality wi l l both be affected in a positive manner. OPN

Light Touch continued from page 56

various amounts. The light reflects off the back wall of the droplet and exits toward your eye. Only a small band of wavelengths from each droplet ac­tually reaches your eyes, which cre­ates different colored droplets. The color depends on the location of the water relative to the sun and to your eyes. A ring of colored water vapor can be seen, and we all see a slightly different rainbow because no one stands in exactly the same place.

The light is also linearly polar­ized in the direction of the bow. The sunglasses act as an analyzer that only allows one orientation of polarized light through. As you rotate your head, you allow different parts of the rainbow to pass through to your eyes.

Sunsets and rainbows are com­mon optical phenomena to which chil­dren can relate. Curious questions that children ask about such phenom­ena can open up an opportunity to help them understand the nature of science. OPN

J E F F BROMBERG is a principal special­ist, supplier management, with McDon­nell-Douglas Aerospace, St. Louis, Mo.

OPTICS & PHOTONICS N E W S / M A R C H 1994 59