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Insulating box in a lightning storm

  1. Jun 8, 2014 #1
    This question is a variation on another question I asked recently.

    Suppose you were in a box made from a perfectly insulating material, and a thunderstorm was raging all around you. Would the box offer you any protection from lightning strikes?

    I think it would, because there would be no induced charge on the surface of the box and thus no 'reason' for lightning to hit it. Does this reasoning make sense?
     
  2. jcsd
  3. Jun 8, 2014 #2
    Yes but the thunder can hit nearby objects (for example if the box is under a tree the thunder can hit the tree and not sure what could happen to the insulating box).
     
  4. Jun 8, 2014 #3

    Vanadium 50

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    What does the box do to the lightning's electric field?
     
  5. Jun 8, 2014 #4
    so you mean the thunder can pass through the box?
     
  6. Jun 8, 2014 #5

    Vanadium 50

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    Of course the thunder can pass through the box. Thunder is sound. My question/hint - what does the box do to the lightning's electric field?
     
  7. Jun 9, 2014 #6
    You dont have to be ironic, as far as i know thunder is an electric discharge between a cloud and a point in the ground, while lightning is the discharge between two clouds.

    An insulating box cant block the electric field from an outside source.
     
  8. Jun 9, 2014 #7

    TumblingDice

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    That isn't the correct definition of thunder. You should also check the definition of ironic.
     
  9. Jun 9, 2014 #8
    Yes apparently in english the word thunder is used for the sound of lightning. Ok then. The words when translated in greek have the meaning i ve told though.
     
  10. Jun 9, 2014 #9
    First, why does lightning even create an electric field? I know that there's an electric field between the cloud and the ground -- this is of course what causes the lightning strike. But why would a lightning bolt, which is essentially just a big current, create its own electric field?

    Second, why would this hypothetical electric field be harmful?
     
  11. Jun 9, 2014 #10
    Currents can create their own electric field when they are time varying (and the current of the "lightning bolt" is time varying. Thats why u hear parasites on radio or see distortion on the tv when a nearby lightning hits the sky.)

    If the electric field is too strong it can cause serious problems to human body (from burns in the skin to cancer and even instanteneous death ).
     
  12. Jun 9, 2014 #11
    Huh, interesting.

    Approximately how far away from the lightning strike would you have to be to experience these effects? That is, if we agree that a lightning bolt won't strike a perfectly insulating box, how big would it have to be to keep a person inside at a safe enough distance from any possible nearby lightning strikes?
     
  13. Jun 9, 2014 #12
    Well i can briefly say that the electric field is inversely proportional to the distance from the current source, that is E~(1/r) where r is the distance. So at a distance of 10 meter is 10 times weaker than it is at a distance of 1m, at a distance of 100 meter is 100 times weaker than it is at distance of 1m and so on.
     
  14. Jun 10, 2014 #13

    Drakkith

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    The ionized channel through the air that the lightning takes is made up of ionized gas. This ionized gas is a good conductor of electricity. Applying a large voltage to an ungrounded conductor will charge it. So the ionized channel is charged to whatever the voltage of the cloud is, and getting near this channel is exactly the same as getting close to a highly charged conductor. (since that's essentially what it is)

    So if the channel of ionized air decides to include you or even be near you, then you will become part of the circuit and current will flow through you, causing severe injury and possible death.

    I know of people who have been about 20-30 feet away from a strike and not been injured, so I would guess that to be about a minimum distance. Any closer and you're likely to injured.
     
  15. Jun 10, 2014 #14

    Drakkith

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    Actually the electric field strength is inversely proportional to the square of the distance, so at 10 meters it is 100 times weaker than at 1 meter, and at 100 meters it is 10,000 times weaker than at 1 meter.
     
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