Physics for Scientists and Engineers
10th Edition
ISBN: 9781337553278
Author: Raymond A. Serway, John W. Jewett
Publisher: Cengage Learning
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Chapter 27, Problem 42AP
Two resistors R1 and R2 are in parallel with each other. Together they carry total current I. (a) Determine the current in each resistor. (b) Prove that this division of the total current I between the two resistors results in less power delivered to the combination than any other division. It is a general principle that current in a direct current circuit distributes itself so that the total power delivered to the circuit is a minimum.
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In a circuit, all the power delivered by the battery must be dissipated by the elements to the circuit. This is
simply a statement of the conservation of energy. How much energy dissipated depends on the resistance of
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problems are as follows. For a circuit element, the power dissipated (or generated) is P = IV, where Vand I are
the voltage across and current through a circuit element. We know that a resistor obeys OhmA ¢A^A^'s Law
V=IR, which means that for a resistor, the power dissipated is P = I*R = V²/R.
Consider the following two circuits with identical batteries and re-
sistors.
А
В
C
R
R
R RS
R
If the power dissipated by the resistor in circuit A is P, what is the
power dissipated by one resistor in circuit B?
If the power dissipated by the resistor in circuit A is P, what is the
power dissipated by one resistor in circuit C?
When unequal resistors are connected in series across an ideal battery,
a
the same power is dissipated in each one.
b
the potential difference across each is the same.
c
the current flowing in each is the same.
d
the equivalent resistance of the circuit is less than that of the smallest resistor.
e
the equivalent resistance of the circuit is equal to the average of all the resistances.
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Lx Give Up?
Consider the circuit shown in the diagram. Before the switch is closed, both capacitors are uncharged.
V = 9 V
C = 3.0 pF
C, = 4.5 µF
R = 90 2
R2 = 20 2
R = 60 Q
Immediately after the switch is closed, what is the amount of current supplied by the battery?
Iinitial =
Assuming the switch remains closed for a long time, which capacitor will be the first to reach 95% of its final charge level?
OC,
What is the time constant for charging this capacitor?
us
48°F
Chapter 27 Solutions
Physics for Scientists and Engineers
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 - Show that the time constant in Equation 27.20 has...Ch. 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 - Show that the integral 0e2t/RCdtin Example 27.11...Ch. 27 - You and your roommates are studying hard for your...Ch. 27 - Prob. 30PCh. 27 - Turn on your desk lamp. Pick up the cord, with...Ch. 27 - Four resistors are connected in parallel across a...Ch. 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 - When two unknown resistors are connected in series...Ch. 27 - The circuit in Figure P27.41 contains two...Ch. 27 - Two resistors R1 and R2 are in parallel with each...Ch. 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 - An ideal voltmeter connected across a certain...Ch. 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 - A voltage V is applied to a series configuration...Ch. 27 - The switch in Figure P27.51a closes when Vc23Vand...
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- If the terminals of a battery with zero internal resistance are connected across two identical resistors in series, the total power delivered by the battery is 8.00 W. If the same battery is connected across the same resistors in parallel, what is the total power delivered by the battery? (a) 16.0 W (b) 32.0 W (c) 2.00 W (d) 4.00 W (e) none of those answersarrow_forwardConsider a series RC circuit as in Figure P28.38 for which R = 1.00 M, C = 5.00 F, and = 30.0 V. Find (a) the time constant of the circuit and (b) the maximum charge on the capacitor after the switch is thrown closed. (c) Find the current in the resistor 10.0 s after the switch is closed.arrow_forwardPower P0 = I0 V0 is delivered to a resistor of resistance R0. If the resistance is doubled (Rnew = 2R0) while the voltage is adjusted such that the current is constant, what are the ratios (a) Pnew/P0 and (b) Vnew/V0? If, instead, the resistance is held constant while Pnew = 2P0, what are the ratios (c) Vnew/V0, and (d) Inew/I0?arrow_forward
- An automobile starter motor has an equivalent resistance of 0.0500 and is supplied by a 12.0-V battery with a 0.0100- internal resistance, (a) What is thecurrent to the motor? (b) What voltage is applied to it? (c) What power is supplied to the motor? (d) Repeat these calculations for when the battery connections are corroded and add 0.0900 to the circuit. (Significant problems are caused by even small amounts of unwanted resistance in low-voltage, high-current applications.)arrow_forwardThe terminals of a battery are connected across two resistors in parallel. The resistances of the resistors are not the same. Which of the following statements is correct? Choose all that are correct. (a) The resistor with the larger resistance carries more current than the other resistor. (b) The resistor with the larger resistance carries less current than the other resistor. (c) The potential difference across each resistor is the same. (d) The potential difference across the larger resistor is greater than the potential difference across the smaller resistor. (e) The potential difference is greater across the resistor closer to the battery.arrow_forwardProblem 2. Three resistors R1=2 ohm, R2=3 ohm, and R3=4 ohm are connected in parallel. The parallel connection is attached to a V= 6{V} voltage source. (a) What is the equivalent resistance? (b) Find the current supplied by the source to the parallel circuit. (c) Calculate the currents in each resistor and show that these add together to equal the current output of the source. (d) Calculate the power dissipated by each resistor. (e) Find the power output of the source and show that it equals the total power dissipated by the resistors. (f) draw the diagram.arrow_forward
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