consider the hydrogen atom

Let the electron be in ground state,

Now the current by definition is the amount of charge passing through a cross sectional area in a unit time.

Now the time period for the electron’s rotation,

,

where v = orbital velocity of electron

T=time period of the electron

r= radius of the 1^st orbit.

Now by definition we know current,

Substituting value of T in above equation, we get,

∴ the current produced by revolving electron of hydrogen atom