Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Silly but still hope

  1. Sep 7, 2004 #1
    I posted this on a different thread but I think you people would be better at seeing what I mean. I am a layman so try see what I mean not what I say . Make a circuit that adds or removes electrons from a molecule of air( I just heard a lab has added then removed a electron from a atom of gold) at that moment repel and or attract the air molecule in a desired direction. Can we make it work so that as soon as a particle makes contact it charges then forced to move done over and over again This circuite would cover a surface all air and only the air in contact with the surface would be made to move in the same direction at ever increasing speed. It may make more sense to have it only do this to a % of air. The hope I have is to make a very small amount of air move a small amount just the air in contact with a surface very fast reducing pressure on that surface. The list of things I do not know are extensive how many molecules are in contact with a surface at sea leva
    at normal temps. How much energy to remove a electron or more than one electron from a air molecule .With the mass of a atom or molecule being so large compared to the slight charge can you apply adequate force to move them.
    I will not list the things I do not know but ask for some insight from people with some eduction behind them
  2. jcsd
  3. Sep 8, 2004 #2


    User Avatar
    Science Advisor

    Ionizing air is pretty simple with high voltages. The Sharper Image air filter moves air past its particle collection plates in this manner.

    What application are you trying to use this on? It almost sounds like some sort of magneto-hydrodynamic propulsion or ion drive concept by your description. Neither is simple, inexpensive, or very effective for usage right now as a means of doing much work outside of a few space probes.

  4. Sep 8, 2004 #3
    This may give you a idea make circuit that if a nitrogen atom makes Contact one or more electrons are released at that moment the atom is exposed to a positive charge repealing it forcing a little momentum to be imparted to it before it loses that momentum it is done again and again imparting a little momentum every time (no moving parts). Trying to get a pressure drop with the bernoulli effect. I can not do the math and I know that is what will kill this Idea
  5. Sep 9, 2004 #4


    User Avatar
    Science Advisor

    Ok, I think one flaw is in the "again and again" part of the process you describe.

    Sure an air molecule can become a positive ion by losing an electron to a positively charged plate and then be repeled by the like charge. But as it is repeled away from the plate the force will decrease dramatically - its an exponential curve.

    Also, as with any ion engine, the mass of the molecules is very very small. And with a rapidly decreasing field strength, the quantity of molecules you can operate on is limited to those close to the surface and you will not be able to impart that much energy to each particle as it easily moves away from the surface since its mass is so small.

    Think newton. You're sitting on a wheeled cart and you have bowling balls you can throw out the back. With each ball you toss, you move forward, easy to visualize. Now instead you are trying to toss ping-pong balls to propel yourself forward, and you're only tossing them at the same speed as the bowling ball. Likely not enough force to overcome the static friction in the wheel bearings and tire contact with the ground. You need lots of ping-pong balls and to accelerate them to a high speed to get that forward motion.

  6. Sep 10, 2004 #5
    This would not be a thrust device it is a air pressure reducing device. I hope to push the air over a surface. It would nano electronic circuit creating tiny positive charged plows going over are surface pushing air as fast as electricity can make it move.( Bernulli effect) Think one foot by one foot cube there is around 2160 pounds of pressure on all sides of that surface. Bernulli effect says if we can make the air on one side move faster than the rest the pressure will drop.Think paper thin not large volume. Think little tiny electronic hands covering the top garbing air throwing air acrose that surface as fast as electricity will alow. How fast can we do that? How much would that 2160 pounds of pressure drop? How much energy would it need? I know we can do these things. We already do but in different applications. This would be a high speed electric fans with no moving parts very little volume. The speed on the surface limit should be friction heat since we are using electricity to move it. As for the heat from charging the air the volume of that air is so small and we will only do a % of the air and only be charging a fraction of a second it should dissipate. It takes math to know if this a laymans silly fantasie ,or some thing that mite work but not be paretical ,or really some thing worth trying to do.
  7. Mar 14, 2007 #6
    Im doing something similar

    I want to know if threr is a way of creating something that will be repeled by air with some force. You guys seem to know what you'r talking about.

    Any ideas?

  8. Mar 15, 2007 #7
    If I get what you are talking about, I think there was a mythbusters episode about this. They ordered this device what was shaped like a triangle and ran on 10kV. It was really neat...when they applied power to it, it lifted off the ground and started flying around. It used the principle of ionization to levetate and they could feel air blowing around it.

    After searching I found an example of a similiar one: http://jnaudin.free.fr/html/lftphv.htm
    Last edited: Mar 15, 2007
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook