Question

Consider an electron in a hydrogen atom, revolving in its second excited state (having radius $4.65\mathring{A}$). The de-Broglie wavelength of this electron is:

• A. $12.9\mathring{A}$
• B. $3.5\mathring{A}$
• C. $9.7\mathring{A}$
• D. $6.6\mathring{A}$

Answer 1

The correct option is C $9.7\mathring{A}$

$2\pi r_n=n{\lambda }_n$
${\lambda }_3=\frac{2\pi (4.65\times {10}^{-10})}{3}$
${\lambda }_3=9.7A^{\circ }$