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Static Electricity

  1. May 12, 2012 #1
    What does static mean ?

    Why is a positive charge attracted to a negative charge ? What makes them attractive ?
  2. jcsd
  3. May 12, 2012 #2


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    The word static means "fixed" or "unmoving." In this context, it means there's no current: charges aren't flowing around. They are stationary and just slowly build up on surfaces, until two surfaces with opposite net charge get close enough that a "discharge" can occur (all of the unbalanced charges on one surface suddenly travel to the other surface and vice versa, making everything neutral). This is the "shock" that stings you when you get a build up of static on your body and then touch something else.

    The charges are attracted to each other by the electric force. As for "why", the best answer we can give you is, "because that's the way the electric force works." Any two electric charges will experience a force between them. If those two charges are of the same type, then that force will repulsive. If the charges are of opposite types, the force between them will be attractive.

    Magnetism and electricity are two aspects of the same phenomenon, which is called electromagnetism. Electromagnetism is one of the four *fundamental* forces of nature along with gravity, the strong nuclear force, and the weak nuclear force.

    There are well-tested theories that unify electromagnetism and the weak force, (i.e. they can both be explained using the same underlying theory). There are some theories now that are attempting to unify all four forces, but for now, there is no better answer to the question of "why" there are four forces and why they work they way they do other than, "because that is the way nature fundamentally works."
  4. May 12, 2012 #3
    So you can be here.

    Without the electromagnetic force there would be no electrons bound to atoms ...no elements....just 'lonely' nuclei wandering around....no nothing except maybe space and time.
  5. May 15, 2012 #4
    Both of your explanations have been very explicit to me. My question was "why" but as cepheid said we don't really understand how the universe fundamentally works. I thought we already knew about it.

    I want to know the name of the underlying theory that unifies Electromagnetism and Weak force.

    My next question is :

    When the wind comes into contact with the clouds, the electrons come out of the cloud. This creates a positive charge on the cloud. This attracts electrons on the surface of the earth. When there is enough charges,i.e, when the force of attraction is strong enough, the electrons from the earth's surface move to neutralise the positive charges.

    The electrons move from downwards to upwards, so why do we see lightning moving from upwards to downwards ?
  6. May 15, 2012 #5


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    That's NOT what I said. What I said was that we DO have AN understanding of how the universe fundamentally works, and our BEST current understanding of how the universe fundamentally works is that there are four types of forces. Some of these have been unified, but for the most part, we don't yet have a fully-fledged underlying theory that explains WHY there are four forces and not five, or three, and why the forces have the relative strengths that they do. That's not actually true: we do have such theories, but they are not yet subject to experimental test.

    It could be that there is such a theory that will explain these things, OR it could be that there are NO answers to these questions and *that's just the way it is.* If so, then any further "why" questions are not within the realm of science to answer. Science describes HOW nature works. That is its purpose. Some "why" questions can be answered by answering the "HOW" i.e. by explaining the underlying mechanism for a phenomenon. But eventually, as you keep digging deeper for more and more fundamental underlying explanations for things, you will reach a point where the answer to your "why" question is simply, "because that's the way nature is." At that point, it is not the purpose of science to explain "why" it is that way.

    The electroweak theory. http://en.wikipedia.org/wiki/Electroweak_interaction
  7. May 15, 2012 #6


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    I think that there are still some aspects of lightning that are not fully understood. I certainly am not an expert.

    However, a brief glance at the Wikipedia article suggests that you simply have things backwards: you get a surplus of negative charge on the cloud, not a deficit:

  8. May 19, 2012 #7
    I understood what you said. But still theories like the "String theory" seems too much fictional to me in a sense.

    Thanks, I'll read more about the Electroweak theory.
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