The first telegraphic messages crossed the Atlantic in 1858, by a cable 3000 km long laid between Newfoundland and Ireland. The conductor in this cable consisted of seven copper wires, each of diameter 0.73 mm, bundled together and surrounded by an insulating sheath. (a) Calculate the resistance of the conductor. Use3⋅10−8ohm-meter for the resistivity of the copper, which was of somewhat dubious purity. (b) A return path for the current was provided by the ocean itself. Given that the resistivity of seawater is about 0.25 ohm-meter, see if you can show that the resistance of the ocean return would have been much smaller than that of the cable. (Assume that the electrodes immersed in the water were spheres with radius, say, 10 cm.)