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Sunday Science: Making a homemade compass 週日科學：自製指南針
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！
Sunday, Mar 02, 2008,Page 14
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照片： MICHAEL KEARNEY
PHOTO: MICHAEL KEARNEY, TAIPEI TIMES
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Have you ever used a compass to find your way? Today we’re going to find out why compasses point north and make our own homemade compass.
What you will need:
A plate (with raised edges).
A cork, or something else that floats.
A magnet.
A needle, or a wire-like piece of metal.
Water.
Scissors.
▲ Put water into the plate. The water should be about 1cm deep.
▲Cut the cork so that it’s shaped like a NT$10 coin. The cork will be able to float on water and turn with very little friction. If you don’t have cork, what else do you think would work?
▲You need to make the needle (or other piece of metal) magnetic. Rub the needle in a circular direction along the magnet. Make sure the metal is thin because the compass needs to be very light to work properly. Be careful not to poke yourself with the needle.
▲ Attach the needle lengthwise to the top of the cork. A staple works well.
▲ Place the compass into the water. Be careful not to disturb the water. Make sure there isn’t any wind blowing on the water or anything nearby that might interfere with the magnet.
▲ The compass should slowly turn until it’s pointing north. Try magnetizing the needle and placing it in the water a few times to test how well it works. Don’t forget to record your observations in your Science Journal.
(MICHAEL KEARNEY, STAFF WRITER)
你曾經用指南針找路嗎？今天我們將找出指南針為什麼總是指向北方，並動手自製一個指南針。
所需材料︰
一個碟子（碟緣隆起）
一個軟木塞，或某個漂浮物體
一個磁鐵
一根針，或鐵絲類金屬
水
剪刀
▲ 在碟中裝水，水深約一公分。
▲ 把軟木塞剪成一枚十元硬幣的形狀，這樣軟木就能漂在水上，翻轉時也不會產生太大的摩擦力。若你沒有軟木，你想可以用什麼代替呢？
▲ 把針和磁鐵放在一起繞圓摩擦，這樣你就可以讓針（或金屬絲）帶有磁性；你必須要選用夠細的金屬絲，因為指南針負擔要輕才能順利運作了；另外要注意別被針戳到了。
▲ 把磁針橫放固定在軟木片上，訂書針效果很好。
▲ 將你的指南針放到水面上，小心不要攪亂水面，並要避免讓風吹過水面或其他可能干擾磁鐵的東西。
▲ 指南針這時應該會緩慢轉動，最後指向北方；使針帶有磁性再放到水中幾次，實驗看看成效如何。別忘了在《科學日誌》裡記下你的觀察。
（翻譯︰袁星塵）
WHAT'S THE SCIENCE? 科學原理
Magnets have a northern and a southern end. The northern end is attracted to the southern end (and vice versa). The needle of a compass is just a very light magnet that’s able to spin with very little friction. The earth has a magnetic north pole and a magnetic south pole. These poles are close to, but not exactly at, the earth’s axis of rotation. What’s more, they are constantly moving! Think of the earth as having a big bar magnet stuck through it, with the southern end located at the magnetic north pole. The northern end of the compass will point toward the magnetic north pole. Because the earth is so big, its magnetic field is weak on the surface. That’s why the compass needs to be light and turn on a surface with very little friction.
磁鐵有分N極和S極，N極會吸引S極（反之亦然）；指南針的指針是一個極輕的磁鐵，轉時才不會製造太多摩擦力。地球也有南、北兩磁極，這兩極很接近地球自轉的軸線，但並不完全相同；再者，它們不斷地在改變位置！想像有一根大磁條穿過地球，磁條的S極設置在地理北極附近，因此指南針的N極會指向地球的北磁極。因為地球非常大，地表的磁場很弱，所以指南針必須很輕才能克服摩擦力而旋轉。 FURTHER IDEAS 進階點子
There are other ways to build a compass. One problem you might encounter is that your compass keeps bumping into the side of the plate. To avoid this problem, try poking another needle through the cork to act as an axis. If you don’t use a needle, remember to use something pointy to keep the friction to a minimum.
Don’t forget to record your observations in your Science Journal.
要自製指南針還有別的方法喔。這個實驗中你的指南針可能會一直跑到碟子的邊緣，試試看把另一根針穿過軟木片作為軸心來修正這個問題；若你不是用針狀物，也要找一個尖頭的替代品來減低摩擦力。別忘了在《科學日誌》裡記下你的觀察。
| VOCABULARY 今日單字 |
| 1. compass n.
指南針 (zhi3 nan2 zhen1)
2. cork n.
軟木塞 (ruan3 mu4 sai1)
3. magnet n.
磁鐵 (ci2 tie3)
4. friction n.
摩擦力 (mo2 ca1 li4)
5. disturb v.t.
擾亂 (rao3 luan4)
6. interfere v.i.
干擾 (gan1 rao3)
7. axis n.
軸心 (zhou2 xin1)
8. vice versa adv.
反之亦然 (fan3 zhi1 yi4 ran2)
9. rotation n.
自轉 (zi4 zhuan3) |
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| SCIENCE JOURNAL 科學日誌 |
| What do you know about the earth? How about its magnetic field? Have you ever wondered why the earth has a magnetic field? Try checking the Internet to find out.
你對地球有哪些了解呢？你了解地球的磁場嗎？你曾對地球為何有磁場感到納悶嗎？你可以試著上網找出原因。
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| NEXT WEEK 下週預告 |
| For next Sunday’s experiment you will need the following special items: cotton, gravel, sand, dirt, and a water bottle.
下週日的科學實驗，需要特別準備以下的東西︰棉花、小碎石、沙子、泥土和一個水瓶。 |
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