Problem P. 4073. (April 2008)

P. 4073. An electrometer is charged to 3 kV. Then the electrometer is touched with an - initially neutral - metal ball, mounted on an insulating rod, and then the metal ball is taken away and earthed. The process is repeated 10 times, and finally the electrometer reads 1.5 kV. After this, at least how many times must the above process be repeated in order that the electrometer reads less than 1 kV?

(5 pont)

Deadline expired on May 13, 2008.

Statistics:

44 students sent a solution.
5 points:	Almási 270 Gábor András, Berta Katalin, Blázsik Zoltán, Filep Tibor, Fonai Dániel, Harsányi Szabolcs, Hartstein Máté, Hlatky Dávid, Kovács 888 Gábor, Krämer Zsolt, Kunsági-Máté Éva, Lovas Lia Izabella, Marák Károly, Mayer Martin János, Nagy 648 Donát, Najbauer Eszter Éva, Pálovics Péter, Papp Ádám, Pázmán Koppány, Szikszay László, Szolnoki Lénárd, Tamási Mátyás, Tolner Ferenc, Tószegi Károly, Túri Attila.
4 points:	Deák Zsolt, Fonyó Dávid, Iván Dávid, Jakab Dávid, Nagy Loránd, Szük Dániel, Tihanyi Benedek, Tolnai Gábor, Trényi Róbert.
3 points:	6 students.
2 points:	3 students.
1 point:	1 student.

Problems in Physics of KöMaL, April 2008