Sunday, February 21, 2010

The Highly-Charged Arm Hair Theory

After going through the chapter of electrostatics one night before bed, I dreamt of discussing physics with Joshua. Call me freaky!

In my sub-conscious state, I asked, "Do you know why when we bump arms in dry air areas, we feel that sharp zap which we usually call 'static shock', but we don't feel it when we bump elbows, if we do?"

I went on to explain that electric charge gathers only on the surface of an object such that the electric field within the object is zero. Plus, the electric field is much higher on sharp points, like this:



When we move, friction between our bodies and the air or other objects cause electrons to jump on to us. Static electricity usually occurs in dry air areas, like air-conditioned rooms, because water in the air helps electrons move off you quickly, thus preventing a large electron build up.

So, back to the sharp surfaces. On our arms, we have more hair than well, our elbows. And hairs can be considered 'sharp surfaces' compared to our skin. That means, there would be more charge build-up on our arms compared to our elbows, like this:



Each of us would be negatively charged in dry air. And as you know, like charges repel. Hence, when our highly-charged arm hairs come in to contact with another person's highly-charged arm hairs, ZAPP! - we repel.

Crazy dream, huh?

Makes me wonder whether my sub-conscious mind is more brilliant than my conscious mind.

But then again, the validity of The Highly-charged Arm Hair Theory can be doubted. Care to expound on this, Physics people?

Talk nerdy to me! :)

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