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.