Question

The circumference of the second orbit of an atom or ion having single electron ,is $4\times {10}^{-9}$ m.The de-Brogile wavelength of electron revolving in this orbit should be

• A. $2\times {10}^{-9}m$
• B. $4\times {10}^{-9}m$
• C. $8\times {10}^{-9}m$
• D. $1\times {10}^{-9}m$

Answer 1

The correct option is A $2\times {10}^{-9}m$

The circumference of the orbit $=4\times {10}^{9}m$
The orbit number $=2$
$n\lambda =2\pi r$
$\Rightarrow \lambda =\frac{4\times {10}^9}{2}m$
$\Rightarrow \lambda =2\times {10}^{-9}m$