To explain his theory,Bohr used

$A$ particular hydrogen-like ion emits radiation of frequency $3 \times 10^{15} \,Hz$ when it makes a transition from $n=2$ to $n=1$. The frequency of radiation emitted in a transition from $n=3$ to $n=1$ is $\frac{x}{9} \times 10^{15} \,Hz$, where $X = \text{ . . . . . . }$.

The magnitude of angular momentum,orbit radius,and frequency of revolution of an electron in a hydrogen atom corresponding to quantum number $n$ are $L, r$,and $f$ respectively. According to Bohr's theory of the hydrogen atom,which of the following is constant for all orbits?

In Bohr's model,if the atomic radius of the first orbit is ${r_0}$,then the radius of the fourth orbit is

At which excited state of $Be^{3+}$ will the radius of the $e^{-}$ be the same as that of an $H$ atom in the ground state?

The orbital acceleration of an electron in a hydrogen atom is given by: