Physics for Scientists and Engineers with Modern Physics
10th Edition
ISBN: 9781337671729
Author: SERWAY
Publisher: Cengage
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Textbook Question
Chapter 27, Problem 2P
As in Example 27.2, consider a power supply with fixed emf ε and internal resistance r causing current in a load resistance R. In this problem, R is fixed and r is a variable. The efficiency is defined as the energy delivered to the load divided by the energy delivered by the emf. (a) When the internal resistance is adjusted for maximum power transfer, what is the efficiency? (b) What should be the internal resistance for maximum possible efficiency? (c) When the electric company sells energy to a customer, does it have a goal of high efficiency or of maximum power transfer? Explain. (d) When a student connects a loudspeaker to an amplifier, does she most want high efficiency or high power transfer? Explain.
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A capacitor that is initially uncharged is connected in series with a resistor and a 300.0 V emf source with negligible internal resistance. Just after the circuit is completed, the current through the resistor is 0.950 mA and the time constant for the circuit is 6.00 s.
(A) What is the resistance of the resistor? Express your answer with the appropriate units.
(B) What is the capacitance of the capacitor? Express your answer with the appropriate units.
(a) In the figure what value must R have if the current in the circuit is to be 1.1 mA? Take ε1 = 1.5 V, ε2 = 3.5 V, and r1 = r2 = 4.0 Ω. (b) What is the rate at which thermal energy appears in R?
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Chapter 27 Solutions
Physics for Scientists and Engineers with Modern Physics
Ch. 27.1 - To maximize the percentage of the power from the...Ch. 27.2 - With the switch in the circuit of Figure 27.4a...Ch. 27.2 - With the switch in the circuit of Figure 27.6a...Ch. 27.2 - Prob. 27.4QQCh. 27.4 - Consider the circuit in Figure 27.17 and assume...Ch. 27 - Two 1.50-V batterieswith their positive terminals...Ch. 27 - As in Example 27.2, consider a power supply with...Ch. 27 - Figure P27.3 shows the interior of a three-way...Ch. 27 - Prob. 4PCh. 27 - Consider the two circuits shown in Figure P27.5 in...
Ch. 27 - Consider strings of incandescent lights that are...Ch. 27 - You are working at an electronics fabrication...Ch. 27 - In your new job at an engineering company, your...Ch. 27 - A battery with = 6.00 V and no internal...Ch. 27 - A battery with emf and no internal resistance...Ch. 27 - Todays class on current and resistance is about to...Ch. 27 - Why is the following situation impossible? A...Ch. 27 - Calculate the power delivered to each resistor in...Ch. 27 - For the purpose of measuring the electric...Ch. 27 - Four resistors are connected to a battery as shown...Ch. 27 - You have a faculty position at a community college...Ch. 27 - The circuit shown in Figure P27.17 is connected...Ch. 27 - The following equations describe an electric...Ch. 27 - Taking R = 1.00 k and = 250 V in Figure P27.19,...Ch. 27 - In the circuit of Figure P27.20, the current I1 =...Ch. 27 - (a) Can the circuit shown in Figure P27.21 be...Ch. 27 - For the circuit shown in Figure P27.22, we wish to...Ch. 27 - An uncharged capacitor and a resistor are...Ch. 27 - Prob. 24PCh. 27 - In the circuit of Figure P27.25, the switch S has...Ch. 27 - In the circuit of Figure P27.25, the switch S has...Ch. 27 - A 10.0-F capacitor is charged by a 10.0-V battery...Ch. 27 - Prob. 28PCh. 27 - Prob. 29PCh. 27 - Prob. 30PCh. 27 - Prob. 31PCh. 27 - Prob. 32APCh. 27 - Find the equivalent resistance between points a...Ch. 27 - The circuit in Figure P27.34a consists of three...Ch. 27 - The circuit in Figure P27.35 has been connected...Ch. 27 - The resistance between terminals a and b in Figure...Ch. 27 - (a) Calculate the potential difference between...Ch. 27 - Why is the following situation impossible? A...Ch. 27 - When two unknown resistors are connected in series...Ch. 27 - Prob. 40APCh. 27 - The circuit in Figure P27.41 contains two...Ch. 27 - Prob. 42APCh. 27 - A power supply has an open-circuit voltage of 40.0...Ch. 27 - A battery is used to charge a capacitor through a...Ch. 27 - Prob. 45APCh. 27 - (a) Determine the equilibrium charge on the...Ch. 27 - In Figure P27.47, suppose the switch has been...Ch. 27 - Figure P27.48 shows a circuit model for the...Ch. 27 - The student engineer of a campus radio station...Ch. 27 - Prob. 50APCh. 27 - The switch in Figure P27.51a closes when Vc23Vand...
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