產生靜電
在任何時候都有可能無預警的被電到， 你可能正踩過軟毛地毯，然後要去拉門把 突然…觸電了！ 要了解靜電是什麼， 首先我們需要了解物質的自然特性。 所有物質都是由原子構成， 原子則是由三個小部分所組成的， 帶負電的電子， 帶正電的質子， 以及不帶電的中子。 通常一個原子裡的電子與質子所帶的電會抵銷， 因此大部分你遇見的物質都不帶電。 不過電子很微小，而且幾乎微不足道， 經過搓揉或磨擦後可以讓鬆散的束縛電子， 有足夠能量脫離它們的原子，然後附到其他原子上， 在不同的表面間相互遷移。 當這個情況發生時， 原先物體留下的質子多於電子， 這個東西就變成帶正電； 另一物體則累積較多電子而變成帶負電， 這個情況稱為電荷不平衡， 或淨電荷分離。
放電
不過自然界傾向維持平衝， 所以當其中一個新的帶電物體接觸到另一個材料時， 可移動的電子一有機會就會， 移到最需要它們的地方。 不論是跳離帶負電的物體， 或是跳到帶正電的物體上， 都是要試圖回復到中性的電荷平衝。 這種快速的電子移動稱為靜電釋放， 就是我們認知中突然出現的火花。 這個過程並不會發生在所有物體上， 不然你就會隨時被電到。
金屬與絕緣體
像金屬與鹽水之類的導體， 傾向帶有鬆散的外層束縛電子， 這些電子很容易在分子間流動。 相反的，像是塑膠、橡膠 與玻璃之類的絕緣體， 它們有緊密的束縛電子無法輕易跳到別的原子上。 靜電累積幾乎都發生在， 其中一種材料是絕緣體的時候。 當你踩過地毯時， 電子會從你的身體磨擦掉到地毯上， 然而地毯的絕緣毛線會抵抗失去它原有的電子， 雖然你的身體和地毯加在一起仍然算是不帶電， 不過在這兩者間進行了電荷極化， 所以當你去接觸門把時， 金屬門把的鬆散束縛電子會跳到你的手上， 來取代你身體已經失去的電子， 當這發生在臥室時只能算是小麻煩而已， 如果是在空曠的戶外， 靜電可以是自然界中可怕且具毀滅性的力量--閃電。
閃電
在某種情況下電荷分離會發生在雲層中， 我們不知道到底是如何發生的， 有可能與小水滴， 以及其中的冰粒循環有關。 不論如何，中和電荷不平衡要靠朝向另一物體釋放電荷。 例如一朵雲朝向建築物或另一朵雲釋放電荷，放電過程中產生巨大火花──即閃電。 就像你的手指頭會常常被同一個地方電到， 你最好相信閃電也可以再次擊中相同地點。
靜電的科學 - Anuradha Bhagwat(TED)
It can strike without warning, at any moment. You may be walking across a soft carpet and reaching for the door knob when suddenly...zap! To understand static electricity, we first need to know a bit about the nature of matter. All matter is made up of atoms that consist of three types of smaller particles: negatively charged electrons, positively charged protons, and neutral neutrons. Normally, the electrons and protons in an atom balance out, which is why most matter you come across is electrically neutral. But electrons are tiny and almost insignificant in mass, and rubbing or friction can give loosely bound electrons enough energy to leave their atoms and attach to others, migrating between different surfaces. When this happens, the first object is left with more protons than electrons and becomes positively charged, while the one with more electrons accumulates a negative charge. This situation is called a charge imbalance, or net charge separation. But nature tends towards balance, so when one of these newly charged bodies comes into contact with another material, the mobile electrons will take the first chance they get to go where they're most needed, either jumping off the negatively charged object, or jumping onto the positively charged one in an attempt to restore the neutral charge equilibrium. And this quick movement of electrons, called static discharge, is what we recognize as that sudden spark. This process doesn't happen with just any objects. Otherwise you'd be getting zapped all the time. Conductors like metals and salt water tend to have loosely bound outer electrons, which can easily flow between molecules. On the other hand, insulators like plastics, rubber and glass have tightly bound electrons that won't readily jump to other atoms. Static build-up is most likely to occur when one of the materials involved is an insulator. When you walk across a rug, electrons from your body will rub off onto it, while the rug's insulating wool will resist losing its own electrons. Although your body and the rug together are still electrically neutral, there is now a charge polarization between the two. And when you reach to touch the door knob, The metal door knob's loosely bound electrons hop to your hand to replace the electrons your body has lost. When it happens in your bedroom, it's a minor nuisance. But in the great outdoors, static electricity can be a terrifying, destructive force of nature. In certain conditions, charge separation will occur in clouds. We don't know exactly how this happens. It may have to do with the circulation of water droplets and ice particles within them. Regardless, the charge imbalance is neutralized by being released towards another body, such as a building, the Earth, or another cloud in a giant spark that we know as lightning. And just as your fingers can be zapped over and over in the same spot, you better believe that lightning can strike the same place more than once.
授課教師
陳永忠 ycchen@thu.edu.tw