CHAPTER 16. OPTICAL PHENOMENA; PROPERTIES OF MATTER 16.4
For 400 nm:E =
hc
λ=(6, 63 × 10 −^34 )× (3× 108 )
400 × 10 −^9
= 4, 97 × 10 −^19 J
For 580 nm:E =hc
λ=(6, 63 × 10 −^34 )× (3× 108 )
580 × 10 −^9
= 3, 43 × 10 −^19 J
For 650 nm:E =
hc
λ=(6, 63 × 10 −^34 )× (3× 108 )
650 × 10 −^9
= 3, 06 × 10 −^19 J
For 300 nm:E =hc
λ=(6, 63 × 10 −^34 )× (3× 108 )
300 × 10 −^9
= 6, 63 × 10 −^19 J
Therefore, the photons with the highest energy are the ultra-
violet photons.
The photons with the lowest energy are from light which is red.Applications of emissionand absorp-
tion spectra
ESCHM
The study of spectra fromstars and galaxies in astronomy is called spectroscopy. Spec-
troscopy is a tool widelyused in astronomy to learn different things aboutastronomical
objects.
Identifying elements inastronomical objects using their spectra
Measuring the spectrumof light from a star can tell astronomers what the star is made
of! Since each element emits or absorbs light only at particular wavelengths, as-
tronomers can identifywhat elements are in the stars from the lines intheir spectra.
From studying the spectra of many stars we knowthat there are many different types of
stars which contain different elements and in different amounts.