Question

The electron in a hydrogen atom jumps from the ground state to the higher energy where its velocity is reduced to one-third of its initial value. If the radius of the orbit in the ground state is $r$, the radius of new orbit will be

• A. $3r$
• B. $9r$
• C. $\frac{r}{3}$
• D. $\frac{r}{9}$

Answer 1

Answer: (B)

$9r$

Velocity is inversely proportional to $n$, hence $n_2=3$
Radius is directly proportional to square of $n$.
Therefore, $r_3=9r$