Question

The short wavelength limits of Lyman, Paschen and Balmer series in the hydrogen spectrum are denoted by `lambda_L, lambda_P and lambda_B` respectively. Arrange these wavelength in increasing order.

Answer 1

As `1/lambda prop(1/(n_1^2)-1/(n_2^2))`
`1/lambda prop 1/(n_1^2) (because n_2=oo)`
for Lyman series `n_1=1`
for Balmer series `n_1=2`
for Paschen series `n_1=3`.
`:. lambda_(L) lt lambda_(B) lt lambda_(P)`.