Question

When an electrons comes back from fifth orbit to ground state of Hydrogen atom the total number of spectral lines and lines in UV regions are?

Answer 1

Number of visible lines when an electron returns from 5th orbit to the ground state in the H spectrum is 10.

The number of spectral lines =

2

n(n−1)

.

The number of spectral lines =

2

5(5−1)

=10.

These lines belong to the UV region.

Note: Lyman series corresponds to transitions to n=1 level.

Answer 2

Answer:

Number of spectral lines in a series =n

2

−n

1

, where n

2

and n

1

are excited state and ground state respectively.

Number of spectral lines in Lyman series =n

2

−n

1

=5−1=4

Hence, 4 lines appear in Lyman series of hydrogen spectrum when an electron present in 5

th

orbit in an excited hydrogen atom returns back to the ground state.