Final answer:
A short section of an open transmission line appears as a capacitor due to the behavior of the electric field between the conductors. The charging and discharging effect in the transmission line is similar to how a capacitor functions. It accumulates charge on its plates, storing electrical energy.
Step-by-step explanation:
In an open transmission line, a short section can appear as a capacitor at high frequencies due to the behavior of the electric field. The open transmission line consists of two conductors, and when an AC voltage is applied, the electric field between the conductors causes a charging and discharging effect, similar to how a capacitor functions. The short section of the transmission line acts as a capacitor because it accumulates charge on its plates, storing electrical energy.