On which power of the principal quantum number (n) of the orbit, will the magnetic moment `(mu)` of an electron revolving in the Bohr orbit of an atom be directly proportional ?

Explanation

Due to rotation of electron in the n-th orbit, effective current, `I_n=e/(T_n)`
Now, time period, `T_n prop n^3, hence I_n prop 1/(n_3)`
Again, area of n-th orbit ,`A_n =pi r_n^2`
Since, `r_n prop n^2, A_n prop n^4`
Magnetic moment of electron in the n-th orbit,
`mu_n=I_nA_n`
so, `mu_n prop 1/(n_3)*n^4 i.e mu_n prop n`