birbhadra: we are assumming resistance for a given temperature at which resistivity is always the same.........so can't we just keep one single constant K for three constants..divided or multiplied.....in a dimensional analysis........elimination of rho was just to keep a new constant we can keep the rho as it is and get ....R=Rho*L/Pi*(nL)^2 which also implies R is inversely to L tero dai i'm still trying to follow you.........will be back