Obtain an express

According to magnetic dipole moment of revolving electron in Bohr's model

Magnetic moment of the electron is

V is the speed

e is the charge of electron

r is the radius of the orbit

Here is the mass of electron

And also

h is the Plank’s constant

n is the quantum number

For n=1 magnetic moment will be minimum.

It is called Bohr’s model of magnetic dipole moment of an electron.