Q127 / 160 · WBJEE 2009 · Physics
If the electron in a hydrogen atom jumps from an orbit with level $\mathrm{n}_1=2$ to an orbit with level $\mathrm{n}_2=1$ the emitted radiation has a wavelength given by
- A$\lambda=5 / 3 \mathrm{R}$
- Correct answerB$\lambda=4 / 3 \mathrm{R}$
- C$\lambda=\mathrm{R} / 4$
- D$\lambda=3 \mathrm{R} / 4$
Solution
$\frac{1}{\lambda}=R\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)=R\left(\frac{1}{1^2}-\frac{1}{2^2}\right)=\frac{3 R}{4}$
$\Rightarrow \lambda=\frac{4}{3 R}$
Hence, the correct answer is option: 'B'.