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Homework Help: Electroscope Leaves Me Puzzled

  1. Apr 7, 2004 #1
    Electroscope "Leaves" Me Puzzled

    You know what's funny? By looking at the questions being posted, you can see students from all over plowing through the same topics at approximately the same time. People are getting to E&M now.

    Okay, Q.
    An electroscope is a simple device consisting of a metal ball attached by a conductor to two thin leaves of metal foil protected from air disturbances by a jar. When the ball is touched by a charged body, the leaves that normally hang down spread apart. But the leaves of a charged electroscope collapse in time. At higher altitudes, they collapse more rapidly. WHY? (Hint: The existence of cosmic rays was first indicated by this observation.)

    I am completely puzzled. Cosmic rays are certainly beyond my ken. I thought they were fantasy. And now they're spreading leaves apart on mountaintops?

    Thanking you in advance for any help.
  2. jcsd
  3. Apr 7, 2004 #2
    Try finding out the answer to the following: What kind of particles are present in a cosmic ray? Are they charged? See if you can work out with that information.
  4. Apr 7, 2004 #3


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    And you might try reading the problem more carefully- it clearly does NOT say that cosmic rays are "spreading leaves" apart- it says they are causing them to collapse (come together).
  5. Apr 7, 2004 #4
    I don't think snide remarks are in order.
  6. Apr 7, 2004 #5
    Let's not turn this into some kind of personal argument. I think physics is in order, not a fistfight. =]

  7. Apr 7, 2004 #6
    Physics, smysics...really, the last thing I need is for people to tell me to go research cosmic rays or smirk about reading more carefully.

    What did you two do today? Did you go work with the dead and dying, like I did? Did you wash up a dead person today? Did you help the elderly who have been thrown away by their own families? Wipe butts, feed, clean up sputum, suction??? Did YOU take a punch in the nose from a poor guy whose mind is gone? I get off my shift early, due to PUNCHED NOSE, and come home not to some help, but some BULLCORN. THANKS.
  8. Apr 7, 2004 #7
    Now that we've got that out of our systems, back to physics!

    At higher altitudes, there is less atmosphere to shield the electroscope from cosmic rays. So there will be a greater frequency of incidence of cosmic rays. How does that affect our electroscope?

    For reference, cosmic rays are made up of charged particles.

  9. Apr 8, 2004 #8
    Thanks cookiemonster, you're one of the good guys in life. I hope you turn out to have a really good life & get your share of the good stuff. But I give up. :)
  10. Apr 11, 2004 #9


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    Hi Holly: Look up "dosimeter" and read all about how electroscopes are actually used to measure radiation exposure. Cosmic rays are energetic particles; you're exposed to them all the time, and as reported above, the atmosphere protects you from too much exposure. When you fly in a jet, your dose is higher than when on the ground.
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