Mathematical and Physical Journal
for High Schools
Issued by the MATFUND Foundation
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# Problem P. 4294. (November 2010)

P. 4294. An initially stationary, charged, pointlike object can move along a horizontal surface, without friction. Not far from the object there is a long vertical solenoid. The current in thee solenoid is uniformly increased from zero to a given value, and then it is decreased also uniformly to zero again. At the end of this process to which direction will the charged object move with respect to the point P, shown in the figure?

(6 pont)

Deadline expired on December 10, 2010.

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

Megoldás. A töltött test perdületének (impulzusnyomatékának) változása az áramerősség változásával arányos. A folyamat végén a perdület ismét nulla lesz, tehát a töltött test sebessége a $\displaystyle P$ pont felé mjutató, vagy azzal ellentétes irányú vektor kell legyen.

### Statistics:

 7 students sent a solution. 6 points: Bolgár Dániel, Jéhn Zoltán, Nagy Lajos, Szabó 928 Attila. 1 point: 1 student. 0 point: 2 students.

Problems in Physics of KöMaL, November 2010