If the radius of the first orbit of a hydrogen atom is $5.29 \times 10^{-11} \, m$,the radius of the fourth orbit will be ......... $\mathring{A}$.

The radius of the innermost electron orbit of a hydrogen atom is $5.3 \times 10^{-11} \text{ m}$. What is the radius of the $n = 3$ orbit?

The magnetic moment of an electron due to its orbital motion is proportional to (where $n$ is the principal quantum number).

The de Broglie wavelength of the electron in the ground state is $\lambda_1$ and that in the $n = 3$ level is $\lambda_3$. Then $\lambda_3$ is given by:

In a hydrogen atom,the radius of the $n^{th}$ Bohr orbit is $r_n$. The graph between $\log \left( \frac{r_n}{r_1} \right)$ and $\log n$ will be:

In accordance with Bohr's model,find the quantum number that characterizes the Earth's revolution around the Sun in an orbit of radius $1.5 \times 10^{11} \; m$ with an orbital speed of $3 \times 10^{4} \; m/s$. (Mass of Earth $= 6.0 \times 10^{24} \; kg$)