The electron in an atom is restricted to revolve in certain allowed circular orbit known as stationary orbit. The centripetal force for its motion is provided by electrostatic force of attraction between positively charged nucleus and negatively charged electron.
The formula for velocity of an electron in the nth orbit is given as,
vn = 2π2 Kme2 Z / nh
vn =velocity
K = 1/(4πε0) = constant = 9 x 109 N m2 C–2
m= mass of an electron (9.1 x 10–31 Kg)
e = Charge on an electron (1.6 x 10–19 C)
Z= atomic number (No. of Protons)
h= Planck’s constant (6.67 x 10–34 J-s)
n is a positive integer.