A cylindrical aluminium pipe of length 1.42 m has an inner radius of 1.90*10-3 m and an outer radius of 2.90*10-3 m. The interior of the pipe is totally filled with copper. What is the resistance of this unit? (Hint: Imagine that the pipe is connected among the terminals of a battery and decide whether the copper and aluminium parts of the pipe are in parallel or in series.)