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Chapter 4: Q21DQ (page 841)

Ordinary household electric lines in North America usually operate at 120 V . Why is this a desirable voltage, rather than a value considerably larger or smaller? On the other hand, automobiles usually have 12 V electrical systems. Why is this a desirable voltage?

Short Answer

Expert verified

The households have long wires so keep the power the voltage must be kept high.But in the car the wires are small so the resistance is small so there is no need for high voltage.

Step by step solution

01

Power consumption of the electric circuit

Power (P)in an electric circuit is exactly equal to current (I)multiplied by voltage (V).

P=VI=V2R

02

Compare power consumption in household and automobile

The equation of power consumption of an electric circuit is

P=V2R

Since the households have long wires so keep the power the voltage must be kept high.

But in the car the wires are small so the resistance is small so there is no need for high voltage.

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Most popular questions from this chapter

The potential difference across the terminals of a battery is 8.40 V when there is a current of 1.50 A in the battery from the negative to the positive terminal. When the current is 3.50 A in the reverse direction, the potential difference becomes10.20 V . (a) What is the internal resistance of the battery? (b) What is the emf of the battery?

An electron experiences a magnetic force of magnitude4.60×10-15Nwhen moving at an angle of 60.0° with respect toa magnetic field of magnitude3.50×10-3T. Find the speed ofthe electron.

An electron moves at 1.40×106m/sthrough a regionin which there is a magnetic field of unspecified direction and magnitude 7.40×10-2T. (a) What are the largest and smallest possible magnitudes of the acceleration of the electron due to the magnetic field? (b) If the actual acceleration of the electron is one-fourth of the largest magnitude in part (a), what is the angle
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When switch Sin Fig. E25.29 is open, the voltmeter V reads 3.08 V. When the switch is closed, the voltmeter reading drops to 2.97 V, and the ammeter A reads 1.65 A. Find the emf, the internal resistance of the battery, and the circuit resistance R. Assume that the two meters are ideal, so they don’t affect the circuit.

Fig. E25.29.

If a “75-W” bulb (see Problem 25.35) is connected across a 220-V potential difference (as is used in Europe), how much power does it dissipate? Ignore the temperature dependence of the bulb’s resistance.
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