Mathematical and Physical Journal
for High Schools
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# Problem P. 4217. (January 2010)

P. 4217. If the pair of plates, which is to deflect the charges, in the cathode ray tube is uncharged, then the electrons, which are ejected from the electron gun, travel through the tube with a constant velocity and they hit the screen with this speed. What can be stated about the speed of the electrons with which they hit the screen when there is a constant amount of charge on the pair of plates?

(5 pont)

Deadline expired on February 10, 2010.

Sorry, the solution is available only in Hungarian. Google translation

Megoldás. Az elektronok a lemezpártól nagyon messze az ütközés előtt és után is ugyanakkora (zérus) potenciált érzékelnek, tehát a sebességük nagysága nem változik meg, csak az iránya(!).

### Statistics:

 47 students sent a solution. 5 points: Jéhn Zoltán, Patartics Bálint. 3 points: 28 students. 2 points: 3 students. 1 point: 5 students. 0 point: 9 students.

Problems in Physics of KöMaL, January 2010