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I have two 4,000V, 2.5mA, DC power supplies and am attempting to use them in such a way to cause a 6x4x1-inch ABS plastic object to repel dust from the ambient air and prevent this dust from settling on the object.

I understand that two points that have opposite electrical charges will attract each other and that two points that have like electrical charges will repel each other. Using one or both of my power supplies and the plastic object described above, I am looking to somehow charge any potential dust particles that are in a small room and apply the opposite charge to the plastic object.

First Question: Assuming all potential dust particles in the small room can be charged and the plastic object can be given an opposite charge, it should repel the dust particles and prevent them from settling on it. Is this correct?

Second Question: How can I apply a charge to all potential dust particles in the small room?

Third Question: Is it possible to apply a charge to a plastic object of this size? Does the ABS plastic present too high resistance for an object this size?

Fourth Question: If the answer to the third question is yes, what ways can be used to enhance the conductivity of the plastic part. Perhaps a process such as dipping the plastic part in a liquid suspension of copper powder. Any other ideas?

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3 Answers 3

If you just connect your plastic object to your power supply it may or may not become significantly charged. That depends on how big the resistivity of the plastic is relative to that of the air. If you want to make the object more conductive you can just apply some anti static spray. But I do not believe that you can charge all the dust particles in the room. You will probably just end up making dust settle on your object more quickly. Instead I would suggest to build an electrostatic dust filter. http://en.wikipedia.org/wiki/Electrostatic_precipitator If you remove all the dust from the air, none can settle on your object.

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The words you're looking for are static electricity, which isn't the same thing as a current, which you clearly realize.

If you charge the plastic object with some charge (say $Q$), and you (manage to) charge the dust particles with the opposite charge ($-Q$), then the dust would stick to the plastic. You need them both to have the same charge.

Also, if you apply a copper coating (or any other conductive material) to your plastic, it won't really make a difference, apart from perhaps allowing the charge to be spread more evenly across the surface. This question addresses some questions about leakage of charge.

Finally (disclaimer: I don't know if this is physically feasible, it's just an idea) you could charge the plastic with some charge $Q$, and via electrostatic induction the dust particles will probably settle on it. Then if you can reverse the charge on only the plastic, you would be able to repel those dust charges. I can already think of a few problems with this approach, but it may make a starting point for you to think about it.

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well plastic is not a conductor so there would be no way to get it to repel dust. the only solution is to coat it with a metallic coating and then apply a voltage to this coating. Before this, you need to find out the affinity of the dust particles, whether they are likely to become positively or negatively charged. Then you need to connect the terminal of the batttery which has the same polarity. So now after contact with the coating the dust particles will acquire the same type of charge and will get repelled from the coating.

Though plastic can be charged directly by rubbing also it will not be able to retain this charge for long and will soon lose it to water vapour in the atmosphere. Also if it has the opposite affinity as the dust particles then it may end up attracting dust particles rather than repelling it!

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