Mathematical and Physical Journal
for High Schools
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# Problem P. 4263. (May 2010)

P. 4263. The rate of change of the current in a toroidal coil is 10 A/s. The number of turns of the coil is 2000, its cross section is 2 cm2, and the radius of its central circle is 0.5 m. At what acceleration does a proton or an electron starts to move if it is initially at the centre of the toroidal coil?

Hint: The electric field generated by the varying magnetic field of the toroidal coil is similar to the magnetic field generated by a circular current.

(5 pont)

Deadline expired on June 10, 2010.

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

Megoldás. $\displaystyle a=\frac{\mu_{0}}{4\pi}\,\frac{Q}{m}\frac{NA}{4r^2\pi}\frac{\Delta I}{\Delta t}$, melynek segítségével a megadott adatokkal protonra $\displaystyle 1,\!5\cdot 10^{2}$ $\displaystyle m/s^2$, elektronra $\displaystyle 2,\!8\cdot 10^{5}$ $\displaystyle m/s^2$ gyorsulást kapunk.

### Statistics:

 26 students sent a solution. 5 points: Balogh Gábor, Béres Bertold, Bolgár Dániel, Filep Gábor, Fonai Dániel, Galzó Ákos Ferenc, Kaposvári István, Kungl Ákos Ferenc, Laczkó Zoltán Balázs, Patartics Bálint, Pázmán Koppány, Szabó 928 Attila, Varju 105 Tamás. 4 points: Batki Bálint, Jéhn Zoltán, Para Attila. 3 points: 4 students. 2 points: 6 students.

Problems in Physics of KöMaL, May 2010