is kohlrausch's law same for weak and strong electrolytes??

if so, why?

Yes !
The Kohlrausch's law is applied same in both types of the strong and weak electrolytes. Because, it gives the molar conductance of an electrolyte at infinite dilution for both types of electrolyte in which each ion is considered to have its contribution irrespective of the nature of other ion as the weak electrolye dissociate completely at infinite dilution.