Question 1
What does the Einstein coefficient $B_{ul}$ represent in atomic processes?
Question 2
In the context of line formation, what is the effect of increasing optical depth ($\tau_{\nu}$)?
Question 3
Which transition involves an electron moving from a bound state to a free state?
Question 4
What is the primary mechanism for the formation of absorption lines in a spectrum?
Question 5
How does Doppler broadening affect spectral lines?
