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plz solve this numerical ***************************** A coherent length of sodium D2 line is 2.5 cm .deduce coherence time , spectral width of line, and purity factor .given wavelength=5990A°
Asked by 3047-manvir | 04 Jul, 2022, 12:33: PM
answered-by-expert Expert Answer
Wavelength of Sodium D2 line = 589.6 nm
 
Coherent Length L = c × Δτ
 
where c is speed of light and Δτ is coherent time .
 
coherent time  Δτ = L / c = ( 2.5 × 10-2 ) / ( 3 × 108 ) = 8.333 × 10-11 s
 
----------------------------
 
Frequency interval Δν = 1 / Δτ = 1/ ( 8.333 × 10-11 ) = 1.2 × 1010 Hz
 
we know that , ν = c / λ  
 
Hence Δν = - ( c / λ2 ) Δλ
 
where Δλ is spectral width
 
Δλ = ( λ2 × Δν ) / c = ( 5896 × 5896 × 10-16 ×  1.2 × 1010 ) / ( 3 × 108 )
 
Δλ = 13.905 × 10-8 m
 
--------------------------
 
purity factor  Q = Δλ / λ = 13.905 / 5896 = 2.358 × 10-3
 
 
Answered by Thiyagarajan K | 04 Jul, 2022, 23:20: PM
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plz solve this numerical ***************************** A coherent length of sodium D2 line is 2.5 cm .deduce coherence time , spectral width of line, and purity factor .given wavelength=5990A°
Asked by 3047-manvir | 04 Jul, 2022, 12:33: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
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