Sun, Dec 09, 2007 page14

• Sunday Science: Colorful oil slicks 週日科學: 七彩繽紛的水面浮油

  Welcome to Sunday Science! Every Sunday, we're going to guide you through some cool experiments that you can do at home. It's a good idea for you to keep a record of what you do in a Science Journal. That way you can record what you learn, compare results and maybe use them to design new experiments! Have a look at the Science Journal box for some ideas to get you started. Remember to always ask a grown-up's permission before trying out an experiment.
  歡迎閱讀《週日科學版》！我們每週日都要為你介紹可以在家中進行的有趣科學實驗。你可以在《科學日誌》中記錄自己做了哪些活動，這樣就可以將所學的紀錄下來，比較這些結果，也許還可以利用它們來設計新的實驗！先看一下《科學日誌》的點子再開始吧。展開實驗之前，記得要獲得大人許可喔！

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  Have you ever noticed how a slick of oil on a puddle can have a rainbow of colors? This week we're going to make our own colorful oil slicks.

  What you will need:

  a black bowl (or a bowl with the inside covered in black paper)

  

  照片︰MICHAEL KEARNEY

  PHOTO: MICHAEL KEARNEY, TAIPEI TIMES

  a sink

  a desk lamp (optional)

  various kinds of oil (note that sesame oil works well)

  toothpicks

  rubber bands

  ▲ Fill the bowl with water and leave a thin stream of water slowly running over the bowl. This will help clean away the oil. Make sure that the stream is thin enough that no waves are created.

  ▲ Shine the light on the ceiling above the sink. If the room is very bright, this won't be necessary.

  ▲ Dip the end of a toothpick into the oil. Now add a drop of oil to the water. The oil will form a thin film on top of the water. Watch how the light reflects off the oil slick. Try looking at it from different angles.

  ▲ Try using different types of oil. Some work better than others. Use a different toothpick for each type of oil.

  ▲ Try floating a rubber band on top of the water. Add a drop of oil to the middle of the rubber band. Wait a few seconds and then lift up one end of the rubber band.

  ▲ Try adding two oil drops and see how they interact.(MICHAEL KEARNEY, STAFF WRITER)

  你曾經注意過地面上的漂有浮油的水面會反映出彩虹般的色彩嗎？本週我們要來自製七彩繽紛的水面浮油。

  所需材料︰

  一個黑色的碗（或是在有顏色的碗上舖一層黑紙）

  水槽

  一盞桌燈

  多種不同種類的油（麻油的效果尤佳）

  牙籤

  橡皮筋

  ▲ 將碗中裝滿水，並讓保持微弱水量持續流入碗中，這樣可以讓油流走，注意水要開得夠小才不會在水面上產生波紋。

  ▲ 將燈光對著水槽上方的牆壁打。如果房間已經很亮了，可以省略這個步驟。

  ▲ 用牙籤末端浸入油中，用牙籤在水中點一滴油，油會在水面上形成一層薄膜，注意觀察浮油在燈光下的變化。

  ▲ 嘗試用不同種類的油實驗，有些效果比較好，每換一種油就要換一根牙籤喔。

  ▲ 放一根橡皮筋在水面上，然後在橡皮筋中間輕點一滴油，數秒後，挑起橡皮筋一端。

  ▲ 加入兩滴油，看看他們會怎麼互相作用。

  （翻譯︰袁星塵）

  For your information

  Vocabulary 今日單字

  1. slick n. 水面浮油 (shui3 mian4 fu2 you2) 2. film n. 薄膜 (bo2 mo2) 3. reflect v.t./v.i. 反射 (fan3 she4) 4. interact v.i. 互相影響 (hu4 xiang1 ying2 xiang3) 5. transparent adj. 可穿透的 (ke3 chuan1 tou4 de5) 6. wave n. 波 (bo1), 陣動 (zhen4 dong4) 7. wavelength n. 波長 (bo1 chang2) 8. crest n. 波峰 (bo1 feng1) 9. trough n. 波谷 (bo1 gu3) 10. toxic adj. 有毒的 (you3 du2 de5)

  For your information

  What's the science? 科學原理

  When light is shined at the oil slick, some of it reflects off the top of the oil slick and some off the bottom. White light is made up of many different colors of light. Light is a wave. Each color of light has a different wavelength. Waves have both crests and troughs. When a light wave reflects off the oil slick's top, it changes in a way that causes the crests and the troughs to switch places. This happens because air is a lot less dense than oil. But the crests and the troughs don't switch places when light reflects off the bottom of the oil slick. Depending on the thickness of the oil slick and the wavelength of the light, the reflections of a light wave from the oil slick's front and back might meet up in a way that the crests match up, causing a bright color. The conditions at different places in the oil slick are different. That's why you can see so many different colors at once. 當光線照射到浮油表面時，有些在浮油表面就被折射回來，有些則到油底才被折射回來。 白光是由多種不同色的光線組成的，光是波的一種，每種顏色的光都有不同的波長。 波有波峰和波谷，當光從浮油表面折射時，波峰和波谷互換了位置，這是因為空氣比油的密度小很多。但光從浮油底層折射回來時，波峰和波谷並不會交換位置。 依照油層厚度和光線波長，兩個同色的波峰可能交疊，當它們相疊時，你就會看到一個特別亮的顏色了。 浮油層各處的情況都不盡相同，這就是為什麼你會同時看到這麼多顏色的原因了。

  For your information

  Science Journal 科學日誌

  What do you know about oil? Does it mix with water? What is light? What does it do when it hits a transparent surface? 你對油認識多少？油會和水相混合嗎？光線是什麼？當光線碰到一個可穿透的表面時會如何？

  For your information

  Bonus 你知道嗎

  Oil dumped down the sink could end up polluting rivers. For this experiment we're only using a small amount of oil that isn't very toxic. But if you ever need to dump a lot of oil, especially something like car oil, make sure to properly dispose of it. 倒到水槽裡的油可能會造成河流污染，在這個實驗中，我們只使用非常少量的油，因此不會造成太大的傷害。但如果你要倒大量的油，尤其像是汽油等，要用適當的方法回收。

  For your information

  Further ideas 進階點子

  What happens if you drip a lot of oil into the bowl? Does it make more or less colors? What happens when you change your viewing angle? Why do you think this is? Don't forget to record your observations in your Science Journal. 如果你在碗中滴入很多油會如何呢？這樣會反映更多或更少顏色呢？如果你換個角度觀察會如何呢？你認為為什麼會出現這些顏色呢？，別忘了在《科學日誌》裡記下你的觀察。

  For your information

  Next week 下週預告

  For next Sunday's experiment you will need the following special items: a thermometer, a measuring jug, and ice (homemade or store bought, about two bags worth). 下週日的科學實驗，需要特別準備以下的東西︰一個溫度計、一個量杯和冰塊（自製或向商店購買均可，需約兩包的量）。
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