Chapter 4: Q58P (page 845)
A resistor with resistance is connected to a battery that has emf 12.0 V and internal resistance . For what two values of will the power dissipated in the resistor be 80.0 W ?
Short Answer
The two values of are and .
Chapter 4: Q58P (page 845)
A resistor with resistance is connected to a battery that has emf 12.0 V and internal resistance . For what two values of will the power dissipated in the resistor be 80.0 W ?
The two values of are and .
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Get started for freeA light bulb glows because it has resistance. The brightness of a light bulb increases with the electrical power dissipated in the bulb. (a) In the circuit shown in Fig. Q25.14a, the two bulbs A and B are identical. Compared to bulb A, does bulb B glow more brightly, just as brightly, or less brightly? Explain your reasoning. (b) Bulb B is removed from the circuit and the circuit is completed as shown in Fig. Q25.14b. Compared to the brightness of bulb A in Fig. Q25.14a, does bulb A now glow more brightly, just as brightly, or less brightly? Explain your reasoning
Copper has free electrons per cubic meter. A 71.0-cm
length of 12-gauge copper wire that is 2.05 mm in diameter carries 4.85 A of
current. (a) How much time does it take for an electron to travel the length
of the wire? (b) Repeat part (a) for 6-gauge copper wire (diameter 4.12 mm)
of the same length that carries the same current. (c) Generally speaking,
how does changing the diameter of a wire that carries a given amount of
current affect the drift velocity of the electrons in the wire?
Can potential difference between the terminals of a battery ever be opposite in direction to the emf? If it can, give an example. If it cannot, explain why not.
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?
Light Bulbs in Series and in Parallel. Two light bulbs have constant resistances of and . If the two light bulbs are connected in series across a line, find (a) the current through each bulb; (b) the power dissipated in each bulb; (c) the total power dissipated in both bulbs. The two light bulbs are now connected in parallel across theline. Find (d) the current through each bulb; (e) the power dissipated in each bulb; (f) the total power dissipated in both bulbs. (g) In each situation, which of the two bulbs glows the brightest? (h) In which situation is there a greater total light output from both bulbs combined?
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