Question

More emission lines than absorption lines


I just read that, due to some reason ( i want the reason),

All the lines present in absorption spectrum (dark lines against bright background) are present in its emission spectrum (bright lines against dark background), BUT THE CONVERSE IS NOT TRUE..

so I don't get WHY the converse is not true part :-/

Answer 1

So the claim is: every absorption line can be an emission line, but not every emission line can be an absorption line? I don't see why not in theory, given how absorption lines are generated.

Is what your reading in some particular context?

Answer 2

a body which can absorb a particular radiation will emit the same radiation when its "made to", thats the black body radiation theory.. so how come it would not absorb some radiation which it would emit?

Answer 3

Yes, as a matter of general theory, it sounds wrong to me that the two cannot be equal.
E.g., https://www.cfa.harvard.edu/~jbattat/a35/cont_abs_em.html

Answer 4

ok it states that.. the reason is because during emission and absorption, the material is in different physical condition,

so i think, during absorption its cooler, and emission its hotter, could this have anything to do with it?

Answer 5

It's hard to second guess the text you're reading and in what context it is discussing the issue.

If you can, insert the entire paragraph or two or three, and tell us what the chapter/section heading is as well.

Answer 6

Actually this textbook is not discussing all this at this high level, the purpose in that chapter is to introduce the concept of spectrum and its various types, but I am becoming a lecturer, and I wanna know in depth, now there was a small note given which said whatever i had mentioned in the beginning of this thread.

This is under "Introduction to atomic physics" by MES SUBHAS a textbook for second year pre-university (india)

Answer 7

Well, based on what you are reporting, it is wrong. Every emission line can be an absorption line.

Answer 8

So i better not mention that to my students tomorrow :D

Answer 9

I just downloaded Resnik and HAlliday textbook but that text has nothing about this :-/