Question

The magnetic moment $(\mu )$ of a revolving electron around the nucleus varies with principal quantum number $n$ as

• A. $\mu \propto n$
• B. $\mu \propto 1/n$
• C. $\mu \propto n^2$
• D. $\mu \propto 1/n^2$

Answer 1

Answer: (A)

$\mu \propto n$

Answer 2

From Bohr's model of atom, electrons can revolve only in those orbits in which their angular momentum is an integral multiple of $\frac{h}{2 \pi}$, where $h$ is Planck's universal constant. From Bohr's postulate $\mu = \frac{nh}{2 \pi}$ $\Rightarrow \mu \propto n$ where $n$ is integer $(=1,2,3, \ldots \ldots)$ and is called principal quantum number. The discrete orbits in which electrons can revolve are known as stable orbits.