when we go from one end to other

that is perpendicular to flat surfaces.. resistance = rho l/a

 

 

now if we move perp. to curved surfaces....

from one end of diam to other...

 

thn

let l b lenth of cylinder..

and conider dx elemnt ... that is a rectangle with length l and breadth

 2root (R^2 - x^2) =b.... usin geometry

which is at dist. x frm centre of cylinder

 

resistance offred by it = rho dx/lb = dk

 we integrate dk frm 0 - K

and x has limits frm 0- R

thus we get resist. K by half the cylinder .... for full cylinder multiply 2 to ans..

as it is symmetric

 

thus we get the ans.... resistance = 2K

 

 

 

Cheers!!!!!