Charge density of a point charge at origin

[kolahal_b]

Are we justified in writing ρ(r’)=Q[δ^3(r’)] to designate the charge density of a charge Q at origin?I say this because the standard expression is

ρ®=Q[δ^3(r-r’)].

However,I believe the first expression will do as well.

[Qfwfq]

The expression you write is, as you say, for a charge at the origin. The other one is, quite obviously, for a point charge at a position other than the origin. :)