Walker, Halliday & Resnick — Current and Resistance: Problem 6

6 Kiting during a storm. The legend that Benjamin Franklin flew a kite as a storm approached is only a legend—he was neither stupid nor suicidal. Suppose a kite string of radius 2.00 mm extends directly upward by 1.80 km and is coated with a 0.500 mm layer of water having resistivity \(150 \ \Omega \cdot \text{m}\). If the potential difference between the two ends of the string is 213 MV, what is the current through the water layer? The danger is not this current but the chance that the string draws a lightning strike, which can have a current as large as 500 000 A (way beyond just being lethal).