Question

Points: 80
When an electron makes a transition from (n + 1) state to nth state, the frequency of emitted
radiations is related to n according to:

Answer 1

this is based on concept of Rydberg formula ,

e.g 1/lemda = R Z² { 1/n1² - 1/n2² }

here , n1 = n
n2 = n+1

1/lemda = R.Z² { 1/n² - 1/( n +1)² }

= R.Z² { (n+1)² -n²}/n²( n+1)² }

=R.Z² { (2n+1)/n²( n+1)² }

becoz n >> 1
so, 1/n →0

=R.Z² { n( 2+1/n )/n².n²( 1+1/n)² }

=R.Z² { 2/n³}

=2R.Z²/n³

hence, 1/lemda = 2R.Z²/n³

we know ,
C = frequency × wavelength

frequency = C/wavelength

= C × 2R.Z²/n³

=2RC.Z²/n³

hence, option ( A ) is correct .

Answer 2

Hope this helps...........