일반물리학 2 — Electromagnetic Oscillations and Alternating Current: Problem 21

21 An ac generator provides emf to a resistive load in a remote factory over a two-cable transmission line. At the factory a step-down transformer reduces the voltage from its (rms) transmission value \(V_t\) to a much lower value that is safe and convenient for use in the factory. The transmission line resistance is 0.30 \(\Omega\)/cable, and the power of the generator is 300 kW. If \(V_t = 80 \text{ kV}\), what are (a) the voltage decrease \(\Delta V\) along the transmission line and (b) the rate \(P_d\) at which energy is dissipated in the line as thermal energy? If \(V_t = 8.0 \text{ kV}\), what are (c) \(\Delta V\) and (d) \(P_d\)? If \(V_t = 0.80 \text{ kV}\), what are (e) \(\Delta V\) and (f) \(P_d\)?