Question

How many spectral lines are seen for hydrogen atom when electron jump from $n_2=5$ to $n_1=1$ in visible region?

Answer 1

Given

A hydrogen atom, Having $n_2=5$ and $n_1=1$

Total no of the spectral lines $=\frac{(n_2-n_1)(n_2-n_1-1)}{2}$

Here $n_2=5$ and $n_1=1$

Therefore the total no of the spectral line

$\frac{(5-1)(5-1-1)}{2}=\frac{20}{2}=10$

So, the ten lines is

$5\to 4,5\to 3,5\to 2,5\to 1,4\to 3,4\to 2,4\to 1,3\to 2,3\to 1,2\to 1$ are

possible in this case.

Of all this lines only, one's falling in Balmer series are in visible region.

For Balmer series,$x=2$ and $y=3,4,5$

Thus,

$5\to 2,4\to 2,3\to 2$ it shows three lines lie in the visible region.