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Problem P. 4481. (November 2012)

P. 4481. A big piece of positively charged metal sheet is illuminated by light of wavelength \lambda. The surface charge density of the metal is \sigma, and the work function of the metal is W.

a) At what greatest distance from the metal can electrons be found?

b) At what speed do the electrons moving back to the sheet hit the sheet?

(Data: \sigma=2.10-6 C/m2, W=0.41 aJ, \lambda=400 nm.)

(4 pont)

Deadline expired on December 10, 2012.


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

Megoldásvázlat. \(\displaystyle a)\) 2,5 mikron. (Ha \(\displaystyle \sigma\) a fémlemez két oldalának együttes töltéssűrűsége, akkor a legnagyobb eltávolodás 5 mikron.)

\(\displaystyle b)\) \(\displaystyle 4{,}4\cdot10^5\) m/s.


Statistics:

37 students sent a solution.
4 points:Antalicz Balázs, Balogh Menyhért, Barta Szilveszter Marcell, Bingler Arnold, Buttinger Milán, Csáky Pál, Csathó Botond, Csóka József, Czipó Bence, Dávid Bence, Dinev Georgi, Filep Gábor, Garami Anna, Horicsányi Attila, Jenei Márk, Juhász Péter, Kollarics Sándor, Kovács 444 Áron, Medek Ákos, Nagy Zsolt, Nárai Ádám, Olosz Balázs, Pázmán Zalán, Plaszkó Noel, Sisák Mária Anna, Szabó 928 Attila, Tanner Martin, Ürge László, Varju Ákos.
3 points:Forrai Botond.
2 points:4 students.
1 point:3 students.

Problems in Physics of KöMaL, November 2012