Mathematical and Physical Journal
for High Schools
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Problem P. 4354. (May 2011)

P. 4354. A 12 cm long bar magnet is placed vertically above the centre of a horizontal, fixed, open conducting ring, such that the lower end of the magnet is 4 cm from the centre of the ring. The magnet is dropped and when its lower end reaches the plane of the ring the induced e.m.f. between the ends of the ring is +2 V. What are the magnitude and the polarity of the induced e.m.f. at the instants when the centre of the magnet, and when the upper end of the magnet passes the centre of the ring?

(4 pont)

Deadline expired on June 10, 2011.

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

Megoldás. Ha a rúdmágnes tere szimmetrikus a felezősíkjára, akkor a közepe áthaladásakor nem indukálódik feszültség a karikában.

Amikor a felső vége áthalad a karikán, az indukált feszültség $\displaystyle -4$ V lesz.

Statistics:

 23 students sent a solution. 4 points: Antalicz Balázs, Béres Bertold, Bolgár Dániel, Csóka József, Dávid Péter, Dénes Benjámin, Filep Gábor, Juhász Péter, Koncz Gabriella, Maknics András, Nagy 111 Miklós, Pázmán Zalán, Szabó 928 Attila, Szemes Gábor Bence, Vuchetich Bálint. 3 points: Hoffmann Hanna, Pető János. 2 points: 3 students. 0 point: 1 student. Unfair, not evaluated: 2 solutionss.

Problems in Physics of KöMaL, May 2011