1. An AC power generator produces 23 A at 1800 V. The voltage is stepped up to 1

Question

1. An AC power generator produces 23 A at 1800 V. The voltage is stepped up to 110,000 V by a 98% efficient transformer and the energy transmitted through a long distance power line which has a total resistance of 175 . What percentage of the power delivered by the generator is dissipated as heat in the long distance line?

2. An airplane sends out a radar pulse of frequency 1.6x1011Hz. The signal returns to the plane 3.5 µs later. What is the wavelength of the wave? How far is the object that reflected the wave?

Please help show the steps! Thank you so much!!

Explanation / Answer

here,

current, i = 32 A at 1800 V

Power before stepping up, pi = V * I
Power before stepping up, pi = 1800 * 32
Power before stepping up, pi = 57600 watts

stepped up volatge, vs = 110000 V

Resistance, R = 175 ohms

Current after stepped up, Is = 57600 / 110000

Current after stepped up, Is = 0.524 A

Volatge drop, vd = 0.524 * 175
Volatge drop, vd = 91.7 V

dissipation in line = vd * Is
dissipation in line = 91.7 * 0.524
dissipation in line = 48.051 watts

%loss = 48.051 / 57600 * 100

%loss = 0.083 %

Ques 2:
Frequency, f = 1.6*10^11 Hz

Speed of sound at 20 c = 340 m/s

wavelength, w = speed of lsound / frequency

wavelength, w = 340 / (1.6*10^11)

wavelength, w = 2.125*10^-9 m or 2.125 nm

distance travelled, d = speed * time

distance travelled, d = 340 * 3.5*10^-6

distance travelled, d = 0.00119 m

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