An electron is moving round the nucleus of a hydrogen atom

An electron is moving round the nucleus of a hydrogen atom in a circular orbit of radius r. The Coulomb force F^{^→} between the two is

Charges (–e) on electron and (e) on proton exert a force of attraction given by

Force = (K)	(-e)(e)	r̂ =	-Ke²	ṙ		∵ r̂ =	r^{^→}
	r²		r³				\| r \|

Note : Magnitude of Coulomb force is given by

F =	1	.	q₁q₂
	4πε₀		r²

but in vector form F^{^→} =	1	.	q₁q₂	r^{^→}
	4πε₀		r²

	where K =	1
		4πε₀