Suppose there are two transformers between yout house and the high-voltage trans

Question

Suppose there are two transformers between yout house and the high-voltage transmission line that distributes the power. In addition, assume your house is the only one using electric power. At a substation the primary of a step-down transformer (turns ratio = 1:29) receives the voltage from the high-voltage transmission line. Because of your usage, a current of 48mA exists in the primary of this transformer. The secondary is connected to the primary of another step-down transformer (turns ratio 1:32) somewhere near your house, perhaps up on a telephone pole. The secondary of this transformer delivers a 240V emf to your house. How much power is your house using? Remember that the current and voltage given in this problem are rms values.

Explanation / Answer

We assume that the transformers are 100% efficient...then:    input voltage to second transformer =   32 * 240 =    7860 Volts .    input voltage to first transformer = 29 * 7860 =    222720 Volts .    Power used by your home = powerdelivered to first transformer = input current * inputvoltage = .            = 0.048 amps * 222720 Volts =   10691Watts    (that's quite a bit... you shouldturn off some lights)

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