Question

In a hydrogen atom, an electron jumps from second orbit to the first orbit. The wavelength of radiation in $\mathring{A}$ is :

• A. $1.325\times {10}^3$
• B. $2.430\times {10}^3$
• C. $1.215\times {10}^3$
• D. $2.255\times {10}^3$

Answer 1

Answer: (C)

$1.215\times {10}^3$

From Rydberg's equation,

$\nu =R_H(\frac{1}{n_1^2}-\frac{1}{n_2^2})$

$\nu =3.29\times {10}^{15}(\frac{1}{1^2}-\frac{1}{2^2})$

$\nu =2.47\times {10}^{15}cps$

$\lambda =\frac{c}{\nu }=\frac{3\times {10}^8}{2.47\times {10}^{15}}m$

$=1.215\times {10}^{-7}$

$=1.215\times {10}^3\mathring{A}$

Hence, option $\left(C\right)$ is correct.