Find the ratio of wavelengths of first line of Lyman series and second line of Balmer series

Explanation

Use Rydberg formula
`1/(lambdak_alpha)=R_H(1/1^2-1/2^2)`
`1/(lambda_(Lbeta))=R_H(1/2^2-1/4^2)`
`(lambda_(kalpha))/(lambda_(Lbeta))=((16-4)xx4xx1)/(4xx16(4-1))`
`=12/(16xx3)=1/4`