what are the dimensions of resistivity and conductivity ??

and what are their units ??

We know that the unit of resistivity  is Ωm

So dimension of resistivity will have the dimension of resistance(R)/length (L)

Dimension of resistance can be obtained the following way

Dimension of electric potential V = W/q

                                                       = [ML²T^-2]/[AT]

                                                       =  [ML²T^-3A^-1]

Now R = V/I

         [R] = [ML²T^-3A^-1]/[A] = [ML²T^-3A^-2]

[ρ] = [ML²T^-3A^-2][L] = [ML³T^-3A^-2]

SI unit of ρ = Ωm

Conductivity is reciprocal of resistivity

So it will have a dimension of [1/ρ]

[C] = [ML³T^-3A^-2]^-1 = [M^-1L^-3T³A²]

SI unit of conductivity thus becomes Ω^-1m^-1

Ω^-1 is called Siemens S

SI unit of conductivity can also be written as Sm^-1