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Chap27
1. Test Bank, Question 18
A battery has an emf of 9V and an internal resistance of 2
. If the potential difference across its terminals is greater
than 9V:
the current must be out of the negative terminal
it must be connected across a large external resistance
it must be connected across a small external resistance
the current must be zero
the current must be out of the positive terminal
2. Test Bank, Question 1
"The sum of the emf's and potential differences around a closed loop equals zero" is a consequence of:
Newton's third law
Ohm's law
Newton's second law
conservation of energy
conservation of charge
3. Test Bank, Question 21
"The sum of the currents into a junction equals the sum of the currents out of the junction" is a consequence of:
Newton's third law
Ohm's law
Newton's second law
conservation of energy
conservation of charge
4. Test Bank, Question 6
The positive terminals of two batteries with emf's of
1
and
, respectively, are connected together. Here
2
2
>
1.
The circuit is completed by connecting the negative terminals. If each battery has an internal resistance of r, the rate in
watts at which electrical energy is converted to chemical energy in the smaller battery is:
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5. *Chapter 27, Problem 17
In Fig. 27-33, battery 1 has emf
1
= 37.0 V and internal resistance r1 = 0.046 Ω and battery 2 has emf
2
= 37.0 V
and internal resistance r2 = 0.043 Ω. The batteries are connected in series with an external resistance R. (a) What R
value makes the terminal-to-terminal potential difference of one of the batteries zero? (b) Which battery is that?
(a) Number
(b)
0.003
Units Ω
1
6. *Chapter 27, Problem 29
In Fig. 27-40, R1 = 6.99 Ω, R2 = 19.5 Ω, and the ideal battery has emf ε = 10.8 V. (a) What is the magnitude of current
(in A) i1? (b) How much energy is dissipated by all four resistors in 0.570 min?
Figure 27-34
(a) Number
0.266864343958
(b) Number
295.707042253521
Units A
Units J
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7. *Chapter 27, Problem 31
In Fig. 27-42, the ideal batteries have emfs Ε1 = 5.8 V and Ε2 = 14.2 V, the resistances are each 2.2 Ω, and the
potential is defined to be zero at the grounded point of the circuit. What are potentials (a)V1 and (b)V2 at the indicated
points?
(a) Number:
-13
(b) Number:
-10.6
Unit: V
Unit: V
8. *Chapter 27, Problem 35
In Fig. 27-46, ε = 12.3 V, R1 = 1420 Ω, R2 = 2110 Ω, and R3 = 4290 Ω. What are the potential differences (in V) (a)
VA - VB, (b) VB - VC, (c) VC - VD, and (d) VA - VC?
Figure 27-46
(a) Number
5.288695643946
Units V
(b) Number
1.722608712109
Units V
(c) Number
5.288695643946
Units V
(d) Number
7.011304356054
Units V
9. *Chapter 27, Problem 41
In Fig. 27-41, ε1 = 4.05 V, ε2 = 1.35 V, R1 = 7.38 Ω, R2 = 2.40 Ω, R3 = 5.83 Ω, and both batteries are ideal. What is
the rate at which energy is dissipated in (a) R1, (b) R2, and (c) R3? What is the power of (d) battery 1 and (e) battery
2?
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Figure 27-41
(a) Number
0.856691158837
Units W
(b) Number
0.014347734317
Units W
(c) Number
0.404453081893
Units W
(d) Number
1.379872580270
Units W
(e) Number
-0.104380605224
Units W
10. Test Bank, Question 53
A certain galvanometer has a resistance of 100
and requires 1 mA for full scale deflection. To make this into a
voltmeter reading 1 V full scale, connect a resistance of:
1000
900
1000
in parallel
in series
in series
10
in parallel
0.1
in series
11. *Chapter 27, Problem 56
In Fig. 27-62, a voltmeter of resistance RV = 350 Ω and an ammeter of resistance RA = 1.78 Ω are being used to
measure resistance R in a circuit that also contains a resistance R0 = 100 Ω and an ideal battery of emf ε = 12.0 V.
Resistance R is given by R = V/i, where V is the voltmeter reading and i is the current in the resistance R. However, the
ammeter reading is not i but rather i', which is i plus the current through the voltmeter. Thus the ratio of the two meter
readings is not R but only an apparent resistance R' = V/i'. If R = 106 Ω, what are (a) the ammeter reading in
milliamperes, (b) the voltmeter reading (in V), and (c) R'?
Figure 27-62
(a) Number
65.523768651283
Units mA
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(b) Number
5.330990826672
(c) Number
81.359649122807
Units V
Units Ω
12. *Chapter 27, Problem 89
In Fig. 27-76, R = 9.1 Ω. What is the equivalent resistance between points A and B? (Hint: This circuit section might
look simpler if you first assume that points A and B are connected to a battery.)
Figure 27-73
Number
18.2
Units Ω
Significant digits are disabled; the tolerance is +/-2%
13. *Chapter 27, Problem 64
A capacitor with an initial potential difference of 198 V is discharged through a resistor when a switch between them is
closed at t = 0 s. At t = 10.0 s, the potential difference across the capacitor is 1.00 V. (a) What is the time constant of
the circuit? (b) What is the potential difference (in V) across the capacitor at t = 17.5 s?
(a) Number
1.890978640443
Units s
(b) Number
0.018945283448
Units V
14. *Chapter 27, Problem 65
In Fig. 27-66, R1 = 9.75 kΩ, R2 = 14.4 kΩ, C = 0.436 μF, and the ideal battery has emf ε = 20.0 V. First, the switch is
closed a long time so that the steady state is reached. Then the switch is opened at time t = 0. What is the current (in
A) in resistor 2 at t = 4.40 ms?
Number
0.000410915533
Units A
Significant digits are disabled; the tolerance is +/-2%
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15. *Chapter 27, Problem 69
A 2.43 MΩ resistor and a 0.877 µF capacitor are connected in series with an ideal battery of emf ε = 5.00 V. At 1.22 s
after the connection is made, what is the rate at which (a) the charge of the capacitor is increasing (in A), (b) energy is
being stored in the capacitor, (c) thermal energy is appearing in the resistor, and (d) energy is being delivered by the
battery?
(a) Number
0.000001160760
Units A
(b) Number
0.000002529706
Units W
(c) Number
0.000003274094
Units W
(d) Number
0.000005803800
Units W
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