Question

The number of De-Broglie wavelengths contained in the second Bohr orbit of Hydrogen atom is

• A. $1$
• B. $2$
• C. $3$
• D. $4$

Answer 1

Answer: (B)

$2$

De-broglie wavelength of a particle is given as

$\lambda =\frac{h}{mv}$
According to the Bohr's postulate,

$mvr=\frac{nh}{2\pi }$

$⟹2\pi r=n\frac{h}{mv}=n\lambda$

Hence there are $n$ De-Broglie wavelengths in $n^{th}$ Bohr orbit.

Hence correct answer is option B.