(1.) Given a resistance of 5MO. what capacitance value is required to have a tim

Question

(1.) Given a resistance of 5MO. what capacitance value is required to have a time constant of 2s ?
(2.) An equipotential surface in three dimensions for the potential function is represented by: V = y2 - x2 - Z. Find the the function for the electric field for this potential.
(3.) A high voltage transmission line that connects a city 500 km away from a power plant consists of a pair of copper wire, each with a resistance of 4O. The current flows to the city along one wire, and back along the other.
(a.) the transmission line delivers to the city 1.7*105 kW of power at 2.3*105 V. What is the current in the transmission line? How much power is lost as joule heat in the transmission line ?
(b.)if the transmission line were to deliver the same power 1t 110 V, how much power would be lost as joule heat? is it ore efficient to transmit at high voltage or at low voltage?

Explanation / Answer

1) R = 5*10^6 ,

Time constant = RC = 5*10^6*C = 2

C = 4*10^-7F

2) E = (y^2 - x^2 -z)/3

3) a) P = 1.7*10^8 W, V = 2.3*10^5 V

i = P/V = 0.739kA

Power lost = iR^2 = 0.739*10^3*16 = 11.82kW

b) i = P/V = 1.7*10^8/110 = 1.545*10^6kA

Power lost = iR^2 = 1.545*16*10^6 = 24.72*10^6kW

Therefore as the power lost is more in the second case, it is better to transmit at high voltage

Related Questions

Navigate

• Browse (All)
• Browse #
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.