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[Phy] [E2 Atomic World] Aurora Borealis are often observed in

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[E2 Atomic World] Aurora Borealis are often observed in

Aurora Borealis are often observed in skies at high latitudes. When energetic electrons from outerspace collide wit the oxygen atom in the upper atmosphere, the oxygen atoms are excited. The subsequent emission of light is usually green light of wavelength 558nm. The minimum speed of these energetic electrons is of order of magnitude ?
A. 10^(2) ms^(-1)
B. 10^(4) ms^(-1)
C. 10^(6) ms^(-1)
D. 10^(8) ms^(-1)
   

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this Q requires approximation.

KE of electron = energy of the photon

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引用:
原帖由 yeungwk91 於 2016-3-3 01:48 PM 發表
this Q requires approximation.

KE of electron = energy of the photon
First, v=f入
Then, e=hf
Finally 0.5mv^2=hf

am i correct?

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回覆 3# bakhan.golden 的帖子

Yes , correct

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