Emission from hydrogen discharge tube

[utkarshakash]

Homework Statement

In a lab experiment on emission from atomic hydrogen in a discharge tube only a small number of lines are observed whereas a large number of lines are present in the hydrogen spectrum of a star. Why?

The Attempt at a Solution

I think it is related to temperatue but I don't know why.

 

[Simon Bridge]

The lines come from atomic transitions.
What determines which transitions can happen and which get observed?

 

[utkarshakash]

The lines come from atomic transitions.
What determines which transitions can happen and which get observed?

The photons

 

[Simon Bridge]

The photons come from the transitions - what determines which transitions can happen and which get observed?
Do you know how a gas-discharge tube makes light? Why it is a particular color?