  We calculate the effective Komar angular momentum for the Kerr-Newman (KN)
black hole. This result is valid at any radial distance on and outside the
black hole event horizon. The effcetive values of mass and angular momentum are
then used to derive an identity ($K_{\chi^{\mu}}=2ST$) which relates the Komar
conserved charge ($K_{\chi^{\mu}}$) corresponding to the null Killing vector
($\chi^{\mu}$) with the thermodynamic quantities of this black hole. As an
application of this identity the generalised Smarr formula for this black hole
is derived. This establishes the fact that the above identity is a local form
of the inherently non-local generalised Smarr formula.
