Question

what is the formula for finding the no. of spectral lines ?​

Answer 1

Answer:

For example, suppose one atom with an electron at energy level 7 (n2=7). That electron can "de-excite" from n2=7 to n1=6,5,4,3,2, or 1. All those transitions give one spectral line for each. Thus, total of 1×6=n1(n2−n1) (foot note 1) spectral lines would be present in the spectrum.

Answer 2

Explanation:

n(n-1)/2.

hope it is useful.....

mark me as brainleist