Electron of an atom orbiting around a nucleus are permitted to revolve in those orbit for which angular momentum is equal to integral multiple of h/2π, where h is the Planck’s constant.
The equation or formula for Bohr model for postulate 2 is given as,
m vn rn = n h / 2π
m= mass of an electron (9.1 x 10–31 Kg)
vn = velocity of electron in nth state (orbit)
h= Planck’s constant (6.67 x 10–34 J-s)
rn = radius of nth orbit
n is a positive integer