20.5 Alternating Current versus Direct Current

Sinusoidal versus steady flow, rms voltage and current that deliver the same average power, and why transmission runs on AC.

College Physics 2e, 20.5 Alternating Current versus Direct Current

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6 exercises

20.5 Exercise 5

Certain heavy industrial equipment uses AC power that has a peak voltage of 679 V. What is the rms voltage?

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20.5 Exercise 7

Military aircraft use 400-Hz AC power, because it is possible to design lighter-weight equipment at this higher frequency. What is the time for one complete cycle of this power?

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20.5 Exercise 9

In this problem, you will verify statements made at the end of the power losses for the example. (a) What current is needed to transmit 100 MW of power at a voltage of 25.0 kV? (b) Find the power loss in a $1 . \text{00 }- \Omega$ transmission line. (c) What percent loss does this represent?

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20.5 Exercise 11

What is the peak power consumption of a 120-V AC microwave oven that draws 10.0 A?

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20.5 Exercise 13

Two different electrical devices have the same power consumption, but one is meant to be operated on 120-V AC and the other on 240-V AC. (a) What is the ratio of their resistances? (b) What is the ratio of their currents? (c) Assuming its resistance is unaffected, by what factor will the power increase if a 120-V AC device is connected to 240-V AC?

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20.5 Exercise 15

Find the time after $t = 0$ when the instantaneous voltage of 60-Hz AC first reaches the following values: (a) $V_{0} / 2$ (b) $V_{0}$ (c) 0.

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