Ac power is carried to a home via a transmission line, where each wire has a res
ID: 1561245 • Letter: A
Question
Ac power is carried to a home via a transmission line, where each wire has a resistance of 0.36 Ohm. Transformer T_2 at the house has 50 turns on the home side and 1800 turns on the transmission line side. Inside the house, the voltage is 120 V (rms) and a total current of 45 A (rms) is being used by lights and appliances. a) What is the rms voltage on the primary side of transformer T_2? c) If the rms current in the current in the transmission lines is 1.35 A, how much power is being wasted as heat in the lines?Explanation / Answer
a)
On the secondary side the voltage is current times the resistance = > v = iR
v is given to be 120 V.
The relation between the primary and the secondary side of the transformer voltages is :
Vp/Np = Vs/Ns
Vp = NpVs/Ns = 1800*120/50 = 4320 V
b)
Heat wasted = I^2R = 1.35^2*(0.36+0.36) = 1.3122 W.