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  • You probably know the drill: You're handed an exam, and you're told you need to fill out

    你可能很熟悉這個情況:你拿到考試卷,有人告訴你需要

  • the bubbles completely, and then reminded that -- for reasons that no one ever explains

    完全塗滿答案格,並被提醒只能使用 2 號鉛筆

  • -- you can only use a number 2 pencil!

    而且也沒有告訴你為什麼!

  • Now, unless you're an artist, you've probably never even seen a pencil that's not number 2,

    現在,除非你是個藝術家,你可能從來都沒有看過 2 號以外的鉛筆

  • also known as an HB pencil outside the U.S.

    2 號鉛筆在美國以外的國家稱作 HB 鉛筆

  • The thing is, if you used any other kind of pencil when you took an automatically-scored test,

    其實,如果你在考電腦閱卷的考試時,使用其他類型的鉛筆

  • you'd probably be fine.

    可能也沒關係

  • However there are reasons that test instructors still tell you to stick to number 2.

    然而,考試仍然規定你只能使用 2 號鉛筆是有原因的

  • And they have a lot to do with how machines score your tests -- or at least, how they used to.

    因為這跟電腦閱卷機器的閱卷方式有關──或者至少過去是這樣

  • In 1931, a high school physics teacher named Reynold Johnson was grading exams

    在 1931 年,一個名叫 Reynold Johnson 的高中物理老師在改考卷

  • when he wondered if there might be a way to score them without actually having to go through

    他開始思考是否有別的辦法可以不用親自閱卷

  • every single answer by hand.

    就能打分數

  • He knew that graphite, the writing material in pencils, was electrically conductive.

    他知道鉛筆書寫的原料「石墨」可以導電

  • It's made of flat sheets of carbon, and its outer electrons are relatively free to move around

    它是由碳原子平面層所組成,且其外層電子可以相對自由地

  • within the material.

    在物質裡流動

  • So Johnson devised a machine with many small electrical circuits that would pass over an answer sheet.

    所以 Johnson 發明了一台裡面有許多小電路的機器,可以審閱答案卷

  • If there was a pencil mark on the sheet, it would conduct electricity through

    如果有答案欄上有鉛筆畫記痕跡,將會透過其中一個電路導電

  • one of the circuits, and the machine could record it as an answer.

    而後機器可以將其記錄為答案

  • Eventually, he sold the idea to IBM, which produced the first mark-sensing machine.

    最後,他把點子賣給了 IBM,製造出第一個能偵測鉛筆畫記的機器

  • But the number 2 thing didn't become an issue until the next generation of machines were introduced in the 1960s and 70s.

    但是 2 號鉛筆直到第二代機器在 1960 到1970 年代被發明後才受到重視

  • Those machines had light-sensing devices called phototubes, and if they did not detect light

    那些機器裡有叫做光電管的光感測設備,如果在某個點沒有偵測到光

  • in a certain spot, they recorded it as an answer.

    它就會被記錄為答案

  • That made graphite especially useful, because it's better at blocking light than many inks.

    這使得石墨特別有用,因為它阻斷光的效果比其他油墨更好

  • Graphite reflects most light -- that's why pencil marks are so shiny -- and absorbs the rest,

    石墨反射了大多數的光,並且吸收其他的光,這就是鉛筆痕跡如此閃亮的因素

  • which is why it's black.

    使得鉛筆痕跡很黑

  • But for a long time, these optical mark-sensing machines were very picky.

    但有很長一段時間,這些光學標記感應機器是很挑剔的

  • And that's where the different grades of pencil came in.

    而這也正是不同硬度鉛筆出場的原因

  • The graphite in pencils is held together by clay, so manufacturers can control how soft

    鉛筆的石墨是由黏土結合在一起,因此製造商可以控制

  • or hard it is, and also how dark it is. The softer the graphite, the darker the pencil's mark.

    軟硬及深淺程度。石墨越軟,鉛筆畫記越黑

  • Pencils are labeled accordingly.

    鉛筆具有相應的深淺程度標記

  • In the United States, those labels are numbers. International manufacturers use a different system,

    在美國,那些標記用數字表示。國際製造商使用不同的系統

  • with HB corresponding to number 2.

    就像 HB 就等於 2 號

  • Number 2 pencils make marks that are just dark enough to be sensed by the machine,

    2 號鉛筆讓畫記夠黑,足以被機器偵測

  • but also light enough to be erased without leaving a readable mark.

    但也能輕鬆地被擦掉,不留下會被偵測到的殘留痕跡

  • These days, scoring machines use much more advanced sensors that can detect almost any

    近來,閱卷機器使用更先進的感應器,幾乎可以檢測

  • sort of marks you make, as long as they're in the bubbles.

    所有形式的畫記,只要它們在答案框裡

  • So you could probably take your next exam with any kind of pencil you wanted.

    所以下次考試你可以試著用任何一種你想用的鉛筆來作答

  • But your SATs probably aren't the time to test that hypothesis.

    但是,你的 SAT 測驗可能不是驗證這個假設的好時機

  • Maybe bring a couple of number 2s just to be safe.

    或許可以帶一些 2 號鉛筆以防萬一

  • Thanks for asking, and thanks especially to all of our supporters on Patreon, where,

    感謝發問,並特別感謝所有 Patreon 的支持者

  • if you support us at four dollars per month or more, you can submit your questions to be

    如果你願意用一個月四塊錢來支持我們,你可以傳給我們你的問題

  • answered right here on SciShow Quick Questions. And if you want to keep getting smarter with us,

    並由 SciShow Quick Questions 幫你解答。如果你想要和我們一起變聰明

  • don't forget to go to youtube.com/scishow, and subscribe.

    別忘了訂閱 youtube.com/scishow

You probably know the drill: You're handed an exam, and you're told you need to fill out

你可能很熟悉這個情況:你拿到考試卷,有人告訴你需要

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A2 初級 中文 美國腔 鉛筆 石墨 機器 畫記 痕跡 2號

為什麼畫答案卡一定要用 HB 鉛筆? Why Do I Have to Use a Number 2 Pencil?

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    王妍心   發佈於 2017 年 08 月 14 日
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