Question

An electron is moving in 4th orbit and its de-Broglie wavelength is $\lambda$. What is the circumference of the fourth orbit?

• A. $2/\lambda$
• B. $2\lambda$
• C. $4\lambda$
• D. $4/\lambda$

Answer 1

The correct option is C $4\lambda$

Bohr's model says that, $mvr=nh/2\pi$.
As per DeBroglie's theory, $\lambda =h/mv$.
Therefore, $2\pi r=nh/mv=n\lambda$.
DeBroglie's Wavelength of electron in 4th orbit $=\lambda$.
Therefore circumference of 4th orbit $=4\lambda$.