Physics - Modern Physics Question with Solution | TestHub

Number of possible spectral lines emitted when an electron jumps back to ground $$\text{ state from }{\mathrm{n}}^{\text{th }}\text{ orbit }=\frac{\mathrm{n}(\mathrm{n}-1)}{2}$$ Here, $\frac{\mathrm{n}(\mathrm{n}-1)}{2}=6\Rightarrow \mathrm{n}=4$ Wavelength $\lambda$ from transition from $\mathrm{n}=1$ to $\mathrm{n}=4$ is given by, $$\frac{1}{\lambda }=R\left(\frac{1}{1}-\frac{1}{4^2}\right)\Rightarrow \lambda =\frac{16}{15R}=975\mathring{A}$$