Question

The wavelength of radiation required to shift the electron from first Bohr's orbit to infinite Bohr's orbit will be

• A. $252$ $A^{\circ }$
• B. $345$ $A^{\circ }$
• C. $878$ $A^{\circ }$
• D. $911$ $A^{\circ }$

Answer 1

The correct option is D $911$ $A^{\circ }$

Here, $n_1=1$ and $n_2=\infty$.
The equation for wave number(reciprocal of wavelength) is
$\overline{\nu }=\frac{1}{\lambda }=R[\frac{1}{n_1^2}-\frac{1}{n_1^2}]$

$\frac{1}{\lambda }=10.96\times {10}^6[\frac{1}{1^2}-\frac{1}{{\infty }^2}]$

$\frac{1}{\lambda }=10.96\times {10}^6$

$\lambda =\frac{1}{10.96\times {10}^6}$

$\lambda =0.0911\times {10}^{-6}$

$\lambda =911\times {10}^{-10}m$

$\lambda =911A^{\circ }$