Question

The frequency of the first line in Lyman series in the hydrogen spectrum is $\gamma$. The frequency of the corresponding line in the sepectrum of doubly ionized lithium will be

• A. $\gamma$
• B. $4\gamma$
• C. $9\gamma$
• D. $27\gamma$

Answer 1

The correct option is B $4\gamma$

we know that $frequency=c/\lambda$

but $\frac{1}{\lambda }=R{Z}^2(1-\frac{1}{2^2})$ for first line of Lyman series

Here we can see that $\frac{1}{\lambda }\propto Z^2$

For Hydrogen $Z^2=1$ and for helium $Z^2=4$ so frequency in case of Helium will be $four$ times that is $4\gamma$

Option B is correct.