Balmer gave an equation for wavelegth of visible region of H-spectrum as `lambda=(Kn^(2))/(n^(2)-4).
Where n= pricipal quantum number of energy level, K=constant in terms of R (Rydberg constant).
The value of K in term of R is :

Options

A. R
B. `(R)/(2)`
C. `(4)/(R)`
D. `(5)/(R)`

Answer

C

Explanation

`(1)/(lambda) = R [(1)/(2^(2)) - (1)/(n^(2))] = R[(n^(2) - 4)/(4n^(2))]`
`lambda =(4)/(R) xx (n^(2))/(n^(2) - 4)" ".....(i)`
Given:`lambda = (kn^(2))/(n^(2) - 4)" "....(ii)`
Comparing equation (i) and (ii) we have `K = (4)/(R)`