## Quiz 1 #5 [ENDORSED]

$c=\lambda v$

Pauline Tze 3B
Posts: 57
Joined: Sat Jul 09, 2016 3:00 am
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### Quiz 1 #5

Hi, can someone please explain why the photoelectric effect does not apply to this question and what principle you would actually apply?

Question: "5. Iron is an important element in the environment and water systems. Given its environmental significance, we know it emits 510. nm light and absorbs 1.333 x 10^-19 J per photon. What is the energy of light that excites the iron in joules?"

My reasoning was that the emission of light would be the equivalent of kinetic energy (excess) and absorption of light would be the equivalent of threshold energy and the "energy of light that excites the iron" would be the equivalent of the energy in a photon.

Cindy Flores 2C
Posts: 27
Joined: Wed Sep 21, 2016 2:59 pm

### Re: Quiz 1 #5  [ENDORSED]

The concept here would actually be atomic spectra because the question clearly states that the light only excites the atom. Electrons are excited to different n levels, which means light was absorbed to reach that level and it is also emitted when the electron returns to its original state. Photoelectric effect would only be applied when the electron is completely taken out of the atom.