A thin metal cylinder of length L and radius R₁ is coaxial with a thin metal cylinder of length L and a larger radius R₂. The space between the two coaxial cylinders is filled with a material that has resistivity ρ. The two cylinders are connected to the terminals of a battery with potential difference ­ΔV, causing current I to flow radially from the inner cylinder to the outer cylinder. Find an expression for the resistance of this device.