# Quiz 18: Direct-Current Circuits

Physics & Astronomy

Q 1Q 1

The two ends of a 3.0-W resistor are connected to a 9.0-V battery.What is the current through the resistor?
A)27 A
B)6.3 A
C)3.0 A
D)0.33 A

Free

Multiple Choice

C

Q 2Q 2

The two ends of a 3.0-W resistor are connected to a 9.0-V battery.What is the total power delivered by the battery to the circuit?
A)3.0 W
B)27 W
C)0.33 W
D)0.11 W

Free

Multiple Choice

B

Q 3Q 3

The basic function of an electromotive force in a circuit is to do which of the following?
A)Convert electrical energy into some other form.
B)Convert some other form of energy into electrical.
C)Both choices (a) and (b) are valid.
D)None of the above choices are valid.

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Multiple Choice

B

Q 4Q 4

Which voltage is not caused by a source of emf?
A)the voltage across a charged capacitor
B)the voltage across two copper-iron junctions at different temperatures
C)the voltage across the terminals of a dry cell battery
D)the voltage from an electric generator

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Multiple Choice

Q 5Q 5

The internal resistances of an ideal voltmeter and an ideal ammeter are respectively (ideal meaning the behavior of the system is not changed when using the meter):
A)zero and zero.
B)infinite and infinite.
C)zero and infinite.
D)infinite and zero.

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Multiple Choice

Q 6Q 6

When a 24.0-W resistor is connected across a 12.0-V battery, a current of 482 mA flows.What is the internal resistance of the battery?
A)0.02 W
B)0.9 W
C)25.0 W
D)49.8 W

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Multiple Choice

Q 7Q 7

When a 24.0-W resistor is connected across a 12.0-V battery, a current of 482 mA flows.What is the power output delivered by the emf of the battery?
A)0.21 W
B)5.57 W
C)5.78 W
D)6.00 W

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Multiple Choice

Q 8Q 8

When a 24.0-W resistor is connected across a 12.0-V battery, a current of 482 mA flows.What is the resulting terminal voltage of the battery?
A)0.4 V
B)5.8 V
C)11.6 V
D)12.0 V

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Multiple Choice

Q 9Q 9

Three 8.0-W resistors are connected in series.What is their equivalent resistance?
A)24.0 W
B)8.0 W
C)0.38 W
D)0.13 W

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Multiple Choice

Q 10Q 10

Three resistors connected in series each carry currents labeled I

_{1}, I_{2}and I_{3}.Which of the following expresses the value of the total current I_{T}in the system made up of the three resistors in series? A)I_{T}= I_{1}+ I_{2}+ I_{3}B)I_{T}= (1/I_{1}+ 1/I_{2 }+ 1/I_{3}) C)I_{T}= I_{1}= I_{2}= I_{3}D)I_{T}= (1/I_{1}+ 1/I_{2 }+ 1/I_{3})^{-1}Free

Multiple Choice

Q 11Q 11

Three resistors connected in series have individual voltages labeled DV

_{1}, DV_{2}and DV_{3}, respectively.Which of the following expresses the value of the total voltage DV_{T}taken over the three resistors together? A)DV_{T}= DV_{1 }+ DV_{2}+ DV_{3}B)DV_{T}= (1/DV_{1}+ 1/DV_{2}+ 1/DV_{3}) C)DV_{T}= DV_{1}= DV_{2 }= DV_{3}D)DV_{T}= (1/DV_{1}+ 1/DV_{2}+ 1/DV_{3})^{-1}Free

Multiple Choice

Q 12Q 12

Three resistors with values of R

_{1}, R_{2}and R_{3}, respectively, are connected in series.Which of the following expresses the total resistance, R_{T}, of the three resistors? A)R_{T}= R_{1}+ R_{2}+ R_{3}B)R_{T}= (1/R_{1}+ 1/R_{2}+ 1/R_{3}) C)R_{T}_{ }= R_{1}= R_{2}= R_{3}D)R_{T}= (1/R_{1}+ 1/R_{2 }+ 1/R_{3})^{-1}Free

Multiple Choice

Q 13Q 13

Three resistors, with values of 2.0, 4.0 and 8.0 W, respectively, are connected in series.What is the overall resistance of this combination?
A)0.58 W
B)1.1 W
C)7.0 W
D)14.0 W

Free

Multiple Choice

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Multiple Choice

Q 15Q 15

Three resistors, each with resistance R

_{1}, are in series in a circuit.They are replaced by one equivalent resistor, R.Comparing this resistor to the first resistor of the initial circuit, which of the following is true? A)The current through R equals the current through R_{1}. B)The voltage across R equals the voltage across R_{1}. C)The power given off by R equals the power given off by R_{1}. D)R is less than R_{1}.Free

Multiple Choice

Q 16Q 16

If R

_{1}< R_{2}< R_{3},_{ }and if these resistors are connected in series in a circuit, which one dissipates the greatest power? A)R_{1}B)R_{2}C)R_{3}D)All are equal in power dissipation.Free

Multiple Choice

Q 17Q 17

When a light bulb is turned on, its resistance increases until it reaches operating temperature. What happens to the current in the bulb as it is warming up?
A)It stays constant.
B)It increases.
C)It decreases.
D)It increases at first and then decreases.

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Multiple Choice

Q 18Q 18

Resistors of values 8.0 W, 12.0 W, and 24.0 W are connected in series across a battery with a small internal resistance.Which resistor dissipates the greatest power?
A)the 8.0-W resistor
B)the 12.0-W resistor
C)the 24.0-W resistor
D)The answer depends on the internal resistance of the battery.

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Multiple Choice

Q 19Q 19

Three 8.0-W resistors are connected in parallel.What is their equivalent resistance?
A)0.054 W
B)0.13 W
C)0.38 W
D)2.7 W

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Multiple Choice

Q 20Q 20

Three 4.0-W resistors are connected in parallel to a 12.0-V battery.What is the current in any one of the resistors?
A)16 A
B)9.0 A
C)3.0 A
D)48 A

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Multiple Choice

Q 21Q 21

Three resistors connected in parallel have individual values of 4.0, 6.0 and 10.0 W, respectively.If this combination is connected in series with a 12-V battery and a 2.0-W resistor, what is the current in the 10-W resistor?
A)0.59 A
B)1.0 A
C)11 A
D)16 A

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Multiple Choice

Q 22Q 22

Three resistors connected in parallel each carry currents labeled I

_{1}, I_{2}and I_{3}.Which of the following expresses the value of the total current I_{T}in the combined system? A)I_{T}= I_{1}+ I_{2}+ I_{3}B)I_{T}= (1/I_{1}+ 1/I_{2}+ 1/I_{3}) C)I_{T}= I_{1}= I_{2}= I_{3}D)I_{T}= (1/I_{1}+ 1/I_{2}+ 1/I_{3})^{-1}Free

Multiple Choice

Q 23Q 23

Three resistors connected in parallel have the individual voltages labeled DV

_{1}, DV_{2}and DV_{3}, respectively.Which of the following expresses the total voltage DV_{T}across the three resistors when connected in this manner? A)DV_{T}= DV_{1 }+ DV_{2}+ DV_{3}B)DV_{T}= (1/DV_{1}+ 1/DV_{2}+ 1/DV_{3}) C)DV_{T}= DV_{1}= DV_{2 }= DV_{3}D)DV_{T}= (1/DV_{1}+ 1/DV_{2}+ 1/DV_{3})^{-1}Free

Multiple Choice

Q 24Q 24

Three resistors with values R

_{1}, R_{2}and R_{3}, respectively, are connected in parallel.Which of the following expresses the total resistance, R_{T}, of the three resistors when connected in parallel? A)R_{T}= R_{1}+ R_{2}+ R_{3}B)R_{T}= (1/R_{1}+ 1/R_{2}+ 1/R_{3}) C)R_{T}_{ }= R_{1}= R_{2}= R_{3}D)R_{T}= (1/R_{1}+ 1/R_{2 }+ 1/R_{3})^{-1}Free

Multiple Choice

Q 25Q 25

Three resistors, with values of 2.0, 4.0 and 8.0 W, respectively, are connected in parallel.What is the overall resistance of this combination?
A)0.58 W
B)1.1 W
C)7.0 W
D)14.0 W

Free

Multiple Choice

Q 26Q 26

Two resistors of values 6.0 and 12.0 W are connected in parallel.This combination in turn is hooked in series with a 4.0-W resistor.What is the overall resistance of this combination?
A)0.50 W
B)2.0 W
C)8.0 W
D)22.0 W

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Multiple Choice

Q 27Q 27

Two resistors of values 6.0 and 12.0 W are connected in parallel.This combination in turn is hooked in series with a 2.0-W resistor and a 24-V battery.What is the current in the 2-W resistor?
A)2.0 A
B)4.0 A
C)6.0 A
D)12 A

Free

Multiple Choice

Q 28Q 28

Two resistors of values 6.0 and 12.0 W are connected in parallel.This combination in turn is hooked in series with a 4.0-W resistor and a 24-V battery.What is the current in the 6-W resistor?
A)2.0 A
B)3.0 A
C)6.0 A
D)12 A

Free

Multiple Choice

Q 29Q 29

Which two resistors are in parallel with each other?
A)R and R

_{4}B)R_{2}and R_{3}C)R_{2}and R_{4}D)R and R_{1}Free

Multiple Choice

Q 30Q 30

Three resistors, each with resistance R

_{1}, are in parallel in a circuit.They are replaced by one equivalent resistor, R.Compare this resistor to the first resistor of the initial circuit.Which of the following statements is true? A)The current through R equals the current through R_{1}. B)The voltage across R equals the voltage across R_{1}. C)The power given off by R equals the power given off by R_{1}. D)R is greater than R_{1}.Free

Multiple Choice

Q 31Q 31

Resistors of values 6.0W, 4.0W, 10.0W and 7.0W are combined as shown.What is the equivalent resistance for this combination?
A)2.3 W
B)3.0 W
C)10.7 W
D)27 W

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Multiple Choice

Q 32Q 32

What is the equivalent resistance for these 3.00-W resistors?
A)1.33 W
B)2.25 W
C)3.00 W
D)7.50 W

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Multiple Choice

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Q 34Q 34

How much power is being dissipated by one of the 10-W resistors?
A)24 W
B)9.6 W
C)16 W
D)6.4 W

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Multiple Choice

Q 35Q 35

If e = 20 V, at what rate is thermal energy being generated in the 20-W resistor?
A)6.5 W
B)1.6 W
C)15 W
D)26 W

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Multiple Choice

Q 36Q 36

If e = 24 V, at what rate is thermal energy generated in the 20-W resistor?
A)13 W
B)3.2 W
C)23 W
D)39 W

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Q 38Q 38

Consider the circuit shown in the figure.What power is dissipated by the entire circuit?
A)14 W
B)28 W
C)52 W
D)112 W

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Multiple Choice

Q 39Q 39

If R

_{1}< R_{2}< R_{3},_{ }and if these resistors are connected in parallel in a circuit, which one has the highest current? A)R_{1}B)R_{2}C)R_{3}D)All have the same current.Free

Multiple Choice

Q 40Q 40

Resistors of values 8.0 W, 12.0 W, and 24.0 W are connected in parallel across a fresh battery.Which resistor dissipates the greatest power?
A)the 8.0-W resistor
B)the 12.0-W resistor
C)the 24.0-W resistor
D)All dissipate the same power when in parallel.

Free

Multiple Choice

Q 41Q 41

What is Kirchhoff's 1st equation for this junction?
A)I

_{1}= I_{2}+ I_{3}B)I_{2}= I_{1}+ I_{2}C)I_{3}= I_{1}+ I_{2}D)I_{1}+ I_{2}+ I_{3}= 0Free

Multiple Choice

Q 42Q 42

If I

_{1}goes to the right through R_{1}, I_{2}goes to the right through R_{2}, and I_{3}goes to the right through R_{3}, what is the resulting equation resulting from applying Kirchhoff's junction rule at point b? A)I_{1}+ I_{2}+ I_{3}= 0 B)I_{1}+ I_{2}- I_{3}= 0 C)I_{1}- I_{2}+ I_{3}= 0 D)I_{1}- I_{2}- I_{3}= 0Free

Multiple Choice

Q 43Q 43

If I

_{1}goes to the right through R_{1}, I_{2}goes to the right through R_{2}, and I_{3}goes to the right through R_{3}, what is the resulting equation resulting from applying Kirchhoff's loop rule for a clockwise loop around the perimeter of the circuit? A)8.0 V + I_{1}R_{1}+ I_{3}R_{3}= 0 B)8.0 V + I_{1}R_{1}- I_{3}R_{3}= 0 C)8.0 V - I_{1}R_{1}+ I_{3}R_{3}= 0 D)-8.0 V + I_{1}R_{1}+ I_{3}R_{3}= 0Free

Multiple Choice

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Q 49Q 49

Four 1.5-volt AA batteries in series power a transistor radio.If the batteries hold a total charge of 240 C, how long will they last if the radio has a resistance of 200 W?
A)1.1 h
B)2.2 h
C)4.1 h
D)13 h

Free

Multiple Choice

Q 50Q 50

In the circuit segment shown if I = 7 mA and Q = 50 µC, what is the potential difference, V

_{A}- V_{B}? A)-40 V B)+40 V C)+20 V D)-20 VFree

Multiple Choice

Q 51Q 51

If I = 2.0 mA and the potential difference, V

_{A}- V_{B}= +30 V in the circuit segment shown, determine the charge and polarity of the capacitor. A)1.5 mC, left plate is positive B)1.5 mC, right plate is positive C)0.50 mC, left plate is positive D)0.50 mC, right plate is positiveFree

Multiple Choice

Q 52Q 52

If one doubles the emfs in a circuit and doubles the resistances in the circuit at the same time, what happens to the currents through the resistors? Assume there are only emfs and resistors in the circuit.
A)They stay the same.
B)They double.
C)They quadruple.
D)They halve.

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Multiple Choice

Q 53Q 53

A 10-V-emf battery is connected in series with the following: a 2-µF capacitor, a 2-W resistor, an ammeter, and a switch, initially open; a voltmeter is connected in parallel across the capacitor.At the instant the switch is closed, what are the current and capacitor voltage readings, respectively?
A)zero A, 10 V
B)zero A, zero V
C)5 A, zero V
D)5 A, 10 V

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Multiple Choice

Q 54Q 54

A 10-V-emf battery is connected in series with the following: a 2-mF capacitor, a 2-W resistor, an ammeter, and a switch, initially open; a voltmeter is connected in parallel across the capacitor.After the switch has been closed for a relatively long period (several seconds, say), what are the current and capacitor voltage readings, respectively?
A)zero A, 10 V
B)zero A, zero V
C)5 A, zero V
D)5 A, 10 V

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Multiple Choice

Q 55Q 55

A circuit contains a 6.0-V battery, a 4.0-W resistor, a 0.60-µF capacitor, an ammeter, and a switch all in series.What will be the current reading immediately after the switch is closed?
A)zero
B)0.75 A
C)1.5 A
D)10 A

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Multiple Choice

Q 56Q 56

A circuit contains a 6.0-V battery, a 4.0-W resistor, a 0.60-µF capacitor, an ammeter, and a switch in series.What will be the charge on the capacitor 10 min after the switch is closed?
A)zero
B)0.10 mC
C)3.6 mC
D)2.4 mC

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Multiple Choice

Q 57Q 57

A 1 000-V battery, a 3 000-W resistor, and a 0.50-µF capacitor are connected in series with a switch.The capacitor is initially uncharged.What is the value of the current the moment after the switch is closed?
A)0.39 A
B)0.33 A
C)0.84 A
D)2 000 A

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Multiple Choice

Q 58Q 58

A 1 000-V battery, a 3 000-W resistor and a 0.50-µF capacitor are connected in series with a switch.The time constant for such a circuit, designated by the Greek letter, t, is defined as the time required to charge the capacitor to 63% of its capacity after the switch is closed.What is the value of t for this circuit?
A)6.0 * 10

^{9}s B)1.7 * 10^{-10}s C)1.7 * 10^{-7}s D)1.5 * 10^{-3}sFree

Multiple Choice

Q 59Q 59

A 1 000-V battery, a 3 000-W resistor, and a 0.50-mF capacitor are connected in series with a switch.The time constant for such a circuit, designated by the Greek letter, t, is defined as the time that the capacitor takes to charge to 63% of its capacity after the switch is closed.What is the current in the circuit at a time interval of t seconds after the switch has been closed?
A)0.14 A
B)0.21 A
C)0.12 A
D)0.32 A

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Multiple Choice

Q 60Q 60

A certain capacitor is charged to 10 V and then, at t = 0, allowed to discharge through a certain resistor.There will be a certain time before the voltage across the capacitor reaches 5 V.This time can be decreased for this circuit by increasing:
A)the size of the capacitor.
B)the size of the resistor.
C)the size of the time constant.
D)None of the above.

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Multiple Choice

Q 61Q 61

A series RC circuit has a time constant of 1.0 s.The battery has a voltage of 50 V and the maximum current just after closing the switch is 500 mA.The capacitor is initially uncharged.What is the charge on the capacitor 2.0 s after the switch is closed?
A)0.43 C
B)0 66 C
C)0.86 C
D)0.99 C

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Multiple Choice

Q 62Q 62

A voltage source of 10 V is connected to a series RC circuit where R = 2.0 * 10

^{6}W, and C = 3.0 µF.Find the amount of time required for the current in the circuit to decay to 5% of its original value. Hint: This is the same amount of time for the capacitor to reach 95% of its maximum charge. A)3.0 s B)6.0 s C)9.0 s D)18 sFree

Multiple Choice

Q 63Q 63

A series RC circuit, which is made from a battery, a switch, a resistor, and a 3.0-mF capacitor, has a time constant of 9.0 ms.If an additional 6.0-mF is added in series to the 3.0-mF capacitor, what is the resulting time constant?
A)4.0 ms
B)6.0 ms
C)10 ms
D)This cannot be found without the value of the resistance being given.

Free

Multiple Choice

Q 64Q 64

The following three appliances are connected to a 120-V house circuit: i) toaster, 1 200 W, ii) coffee pot, 750 W, and iii) microwave, 800 W.If all were operated at the same time, what total current would they draw?
A)3.0 A
B)5.0 A
C)10 A
D)23 A

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Multiple Choice

Q 65Q 65

What is the maximum number of 60-W light bulbs you can connect in parallel in a 120-V home circuit without tripping the 30-A circuit breaker?
A)11
B)35
C)59
D)3 600

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Multiple Choice

Q 66Q 66

A hair dryer draws 1 200 W, a curling iron draws 800 W, and an electric light fixture draws 500 W.If all three of these appliances are operating in parallel on a 120-V circuit, what is the total current drawn?
A)19.4 A
B)20.8 A
C)25.4 A
D)36.7 A

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Multiple Choice

Q 67Q 67

Household circuits are wired in ________.
A)series
B)parallel
C)both series and parallel
D)neither series nor parallel

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Q 68Q 68

In applications where electrical shocks may be more likely, such as around water in kitchens and bathrooms, special outlets called GFI's are used.What does GFI stand for?
A)get free instantly
B)ground-fault interrupter
C)give fast interruption
D)gravity-free insulator

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Q 69Q 69

Household 120-V outlets are made to accept three-pronged plugs.One of the prongs attaches to the "live" wire at 120 V, and another attaches to the "neutral" wire that is connected to ground.What is the round third prong for?
A)It serves as a backup to the hot wire.
B)It lets the appliance run if the neutral wire breaks.
C)It connects the case of the appliance directly to ground for safety purposes.
D)Nothing electrical, it is for mechanical sturdiness.

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Multiple Choice

Q 70Q 70

Three resistors, each of different value, are used in a circuit with a power source supplying 12 volts.For which of the following resistor combinations is the total power supplied the greatest?
A)all three resistors in series
B)all three resistors in parallel
C)two of the resistors in parallel with the third resistor in series with the parallel pair
D)This cannot be found until it is known which resistor is in series with the parallel pair.

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Multiple Choice

Q 71Q 71

Kirchhoff's rules are the junction rule and the loop rule.Which of the following statements is true?
A)Both rules are based on the conservation of charge.
B)Both rules are based on the conservation of energy.
C)The junction rule is based on the conservation of charge, and the loop rule is based on the conservation of energy.
D)The junction rule is based on the conservation of energy, and the loop rule is based on the conservation of charge.

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Multiple Choice

Q 72Q 72

Using a capacitor and two different value resistors, which of the following combinations in an RC circuit would give the greatest time constant?
A)the capacitor in series with both resistors in series with each other
B)the capacitor in series with both resistors in parallel with each other
C)the capacitor in series with the higher value resistor
D)the capacitor in series with the lower value resistor

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Multiple Choice

Q 73Q 73

Using a resistor and two different value capacitors, which of the following combinations in an RC circuit would give the greatest time constant?
A)the resistor in series with both capacitors in series with each other
B)the resistor in series with both capacitors in parallel with each other
C)the resistor in series with the larger value capacitor
D)the resistor in series with the lower value capacitor

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Multiple Choice

Q 74Q 74

In an RC circuit using two capacitors in series with two resistors, which of the following combinations would give the greatest time constant?
A)both capacitors in series placed in series with both resistors in series
B)both capacitors in parallel placed in series with both resistors in parallel
C)both capacitors in series placed in series with both resistors in parallel
D)both capacitors in parallel placed in series with both resistors in series

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Multiple Choice