Question

what will be the total energy (+ve or -ve) of an electron revolving around nucleus in an atom ?

Answer 1

An atom is electrically neutral which is surrounded by some electrons. This is due to the total negative charge of electrons surrounding the nucleus is equal to total positive charge on the nucleus. Electrons revolve around the nucleus in various circular orbits as do the planets around the sun.

Answer 2

-1/(8π€o)*

$\binom{ - 1}{8\pi}$