Avery long two-wire transmission line, each wire of radius a and separated by a distance d, is supported at a height h above a flat conducting ground. assuming both d and h to be much larger than a, find the capacitance per unit length of the line.

Suppose a diode consists of a cylindrical cathode with a radius of 6.200×10^−2 cm , mounted coaxially within a cylindrical anode with a radius of 0.5580 cm . the potential difference between the anode and cathode is 260 v . an electron leaves the surface of the cathode with zero initial speed (v initial=0). find its speed vfinal when it strikes the anode.