Mathematical and Physical Journal
for High Schools
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Problem P. 4042. (January 2008)

P. 4042. A filament lamp rated at 40 W transforms 2% of the total energy to visible light. Suppose that the time of the emission of one photon is 10-14 second. Find the average number of visible photons emitted by the filament at the same time.

(4 pont)

Deadline expired on February 11, 2008.


Statistics:

85 students sent a solution.
4 points:56 students.
3 points:12 students.
2 points:5 students.
1 point:9 students.
Unfair, not evaluated:3 solutions.

Problems in Physics of KöMaL, January 2008