The external diameter of a 5 metre long hollow tube is 10cm and the th

1.	The external diameter of a 5 metre long hollow tube is 10cm and the thickness of its wall is 5mm. If the specific resistance of copper be 1.7*10 ki power -5 ohm metre, then determine its resistance.solve it fast !!
Answer» GIVEN, $r_{1} = 4.<klux>5</klux>10^{-2} m\\\\r_{2}= 510^{-2}m$ $\rho = 1.710^{-5} ohm m.$ l = 5 m. Let the cross section area of the TUBE be A. We KNOW, A = $\pi(r_{2}^{2} - r_{1}^{2})$ on PUTTING the values, $A = 3.14[(510^{-2})^{2}-(4.510^{-2})^{2}]$ = $14.910^{-4}m^{2}$ ∴ $\rho\frac{l}{A}$ Resistance =* on putting the values, = $\frac{1.710^{-5}5}{14.910^{-4}}$ = 0.57 $10^{-1}$ = 0.057 ohm.