Deck 26: Dc Circuits

Question 1

An RC circuit is connected across a DC voltage source through an open circuit and a switch. As soon as the switch is closed, the charge on the capacitor increases but the voltage across it decreases as a function of time.

Answer 1

False

Question 2

As a dry cell ages, its internal resistance goes up.

Answer 2

True

Question 3

When resistors are connected in parallel, we can be certain that

A)the same current flows in each one.
B)the potential difference across each is the same.
C)the power dissipated in each is the same.
D)their equivalent resistance is greater than the resistance of any one of the individual resistances.

Answer 3

the potential difference across each is the same.

Question 4

Four unequal resistors connected in series have same current but different voltages.

Question 5

An RC circuit is connected across a DC voltage source through an open switch. As soon as the switch is closed, the capacitor charges linearly as a function of time.

Question 6

Four unequal resistors are connected in a series circuit. Which one of the following statements is correct about this circuit?

A)The total resistance is equal to any one of the resistors.
B)The total resistance is equal to average of the four resistors.
C)The total resistance is less than the smallest resistor.
D)The total resistance is less than the largest resistor.
E)The total resistance is more than the largest resistor.

Question 7

Kirchhoff's voltage rule is an example of conservation of energy.

Question 8

A series circuit is a current divider and a parallel circuit is a voltage divider circuit.

Question 9

Three identical resistors are connected in series to a 12-V battery. What is the voltage across any one of the resistors?

A)36 V
B)24 V
C)12 V
D)4 V
E)zero

Question 10

Three identical resistors are connected in series to a battery. If the current of 12 A flows from the battery, how much current flows through any one of the resistors?

A)12 A
B)4 A
C)36 A
D)24 A
E)zero

Question 11

The electromotive force of a battery is the maximum potential difference between the terminals of the battery.

Question 12

The potential difference between the terminals of a battery, when no current flows to an external circuit, is referred to as the

A)emf.
B)terminal voltage.

Question 13

Four equal resistors connected in series have same current and same voltage across each resistor.

Question 14

State Kirchhoff's junction rule.

Question 15

When resistors are connected in series,

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)More than one of the given answers is true.
E)None of the given answers are true.

Question 16

The potential difference between the terminals of a battery, when current flows to an external circuit, is referred to as the

A)emf.
B)terminal voltage.

Question 17

When two or more resistors are connected in series to a battery

A)the total voltage across the combination is the algebraic sum of the voltages across the individual resistors.
B)the same current flows through each resistor.
C)the equivalent resistance of the combination is equal to the sum of the resistances of each resistor.
D)all of the given answers
E)none of the given answers

Question 18

Four equal resistors connected across a DC voltage source in either series or parallel will have equal voltage drops across each resistor.

Question 19

When two or more resistors are connected in parallel to a battery,

A)the voltage across each resistor is the same.
B)the total current flowing from the battery equals the sum of the currents flowing through each resistor.
C)the equivalent resistance of the combination is less than the resistance of any one of the resistors.
D)all of the given answers
E)none of the given answers

Question 20

State Kirchhoff's loop rule.

Question 21

Three identical resistors are connected in parallel to a 12-V battery. What is the voltage of any one of the resistors?

A)36 V
B)24 V
C)12 V
D)4 V
E)zero

Question 22

Which one of the following is a correct statement for a number of resistors connected in series or parallel?

A)The total resistance in a series circuit decreases as more resistors are added.
B)The flow of current is different through resistors connected in a series circuit.
C)The voltage is different across resistors connected in a parallel circuit.
D)The total resistance in a parallel circuit decreases as more resistors are added.
E)None of the above statements is correct.

Question 23

FIGURE 26-8
For the circuit shown in Fig. 26-8, which equation is correct for loop2 (going clockwise)?

A)E₂ + R₃I₃ + E₃ - R₂I₂ = 0
B)E₂ + R₃I₃ - E₃ + R₂I₂ = 0
C)E₂ - R₃I₃ - E₃ - R₂I₂ = 0
D)E₂ + R₃I₃ + E₃ + R₂I₂ = 0
E)-E₂ + R₃I₃ - E₃ + R₂I₂ = 0

Question 24

As more resistors are added in series to a constant voltage source, the power supplied by the source

A)increases.
B)decreases.
C)does not change.
D)increases for a time and then starts to decrease.
E)decreases for a time and then starts to increase.

Question 25

The lamps in a string of Christmas tree lights are connected in parallel. What happens if one lamp burns out? (Assume negligible resistance in the wires leading to the lamps.)

A)The brightness of the lamps will not change appreciably.
B)The other lamps get brighter equally.
C)The other lamps get brighter, but some get brighter than others.
D)The other lamps get dimmer equally.
E)The other lamps get dimmer, but some get dimmer than others.

Question 26

FIGURE 26-9
Which of the following equations represents a Kirchhoff's voltage rule for the circuit shown in Fig. 26-9?

A)-6 V + 2 V - (6Ω) i₃ = 0 V
B)+4 V - (8Ω) i₂ - (12Ω) i₁ = 0 V
C)-(8Ω) i₂ + 4 V + 6 V + (12Ω) i₁ = 0 V
D)+6 V - (12Ω) i₁ - (8Ω) i₂ + 4 V = 0 V
E)none of the above

Question 27

You obtain a 100-W light bulb and a 50-W light bulb. Instead of connecting them in the normal way, you devise a circuit that places them in series across normal household voltage. Which statement is correct?

A)Both bulbs glow at the same reduced brightness.
B)Both bulbs glow at the same increased brightness.
C)The 100-W bulb glows more brightly than the 50-W bulb.
D)The 50-W bulb glows more brightly than the 100-W bulb.

Question 28

Kirchhoff's loop rule is a statement of

A)the law of conservation of momentum.
B)the law of conservation of charge.
C)the law of conservation of energy.
D)the law of conservation of angular momentum.
E)Newton's second law.

Question 29

As more resistors are added in parallel to a constant voltage source, the power supplied by the source

A)increases.
B)decreases.
C)does not change.
D)increases for a time and then starts to decrease.
E)decreases for a time and then starts to increase.

Question 30

FIGURE 26-10
Which of the equations here is valid for the circuit shown in Fig. 26-10?

A)2 - I₁ - 2I₂ = 0
B)2 - 2I₁ - 2I₂ - 4I₃ = 0
C)4 - I₁ + 4I₃ = 0
D)-2 - I₁ - 2I₂ = 0
E)6 - I₁ - 2I₂ = 0

Question 31

FIGURE 26-4
In Fig. 26-4 four identical resistors labeled A to D are connected to a battery as shown. S₁ and S₂ are switches. Which of the following actions would result in the greatest increase in the current through resistor A?

A)closing both switches
B)closing S₁ only
C)keeping both switches open as shown
D)closing S₂ only
E)The answer depends on the value of the emf of the battery.

Question 32

FIGURE 26-6
In Fig. 26-6 shown below what combination of values for the emfs of the batteries would make the electric current in the circuit equal to zero?

A)E₁ = E₃ and E₂ = 2E₁
B)E₁ = E₂ = E₃
C)E₁ = E₂ and E₃ =E₁/2
D)E₁ = E₃ and E₂ =E₁/2
E)E₁ = E₂ and E₃ = 2E₁

Question 33

FIGURE 26-3
In Fig. 26-3 which resistor has the largest value of the electric current?

A)R₃
B)R₂
C)R₁
D)R₄
E)All the resistors have the same current.

Question 34

Kirchhoff's junction rule is a statement of

A)the law of conservation of momentum.
B)the law of conservation of charge.
C)the law of conservation of energy.
D)the law of conservation of angular momentum.
E)Newton's second law.

Question 35

FIGURE 26-1
Fig. 26-1 shows three identical lightbulbs connected to a battery. What happens to the brightness of lightbulb 1 when the switch S is closed?

A)The brightness will increase momentarily then return to its previous level.
B)The brightness increases.
C)The brightness will decrease momentarily then return to its previous level.
D)The brightness remains the same as before the switch is closed.
E)The brightness decreases.

Question 36

FIGURE 26-7
Fig. 26-7 shows a junction with currents labeled I₁ to I₆. Which of the following statements is correct?

A)I₁ + I₃ = I₆ + I₄
B)I₄ + I₃ = I₆
C)I₁ + I₂ = I₆ + I₄
D)I₂ = I₆ + I₄
E)I₆ + I₅ = I₁

Question 37

FIGURE 26-2
In Fig. 26-2 all the lightbulbs are identical. The lightbulbs are ranked in decreasing order of their brightness. What is the correct ranking?

A)(B and C are the same.), A
B)(A & B are the same.), C
C)A, B, C
D)A, (B and C are the same.)
E)All 3 lightbulbs have the same brightness.

Question 38

FIGURE 26-5
In Fig. 26-5 shown below, the resistors A, B and C have resistances R, 2R, and R respectively. Which resistor dissipates the most power?

A)A
B)B
C)C
D)A & B dissipate the same amount of power.
E)All 3 resistors dissipate the same amount of power.

Question 39

Four unequal resistors are connected in a parallel circuit. Which one of the following statements is correct about this circuit?

A)The total resistance is less than the smallest resistor.
B)The total resistance is equal to average of the four resistors.
C)The total resistance is more than the largest resistor.
D)The total resistance is equal to zero.
E)None of the other answers is correct.

Question 40

Three identical resistors are connected in parallel to a battery. If the current of 12 A flows from the battery, how much current flows through any one of the resistors?

A)12 A
B)4 A
C)36 A
D)24 A
E)zero

Question 41

If you connect two identical storage batteries together in series ("+" to "-" to "-" to "+"), and place them in a circuit, the combination will provide

A)zero volts.
B)twice the voltage, and different currents will flow through each.
C)twice the voltage, and the same current will flow through each.
D)the same voltage, and different currents will flow through each.
E)the same voltage, and the same current will flow through each.

Question 42

A voltage reading is obtained by placing a voltmeter across a resistor. What happens to the total current flowing in the circuit as a result of this action?

A)The current increases.
B)The current decreases.
C)The current does not change.
D)The current increases if the meter's internal resistance is less than the original resistance in the circuit and decreases if its internal resistance is greater than the circuit's original resistance.

Question 43

An ideal voltmeter is one that does not change the behavior of a circuit when it is properly used to measure potential difference. The internal resistance of such a meter is

A)dependent on the circuit.
B)infinite.
C)the same resistance as the circuit.
D)0 Ω.
E)cannot be determined

Question 44

An RC circuit is connected across a DC voltage source through an open switch. The switch is closed at t = 0 s. Which of the following is a correct statement regarding the circuit?

A)The capacitor charges to its maximum value in one time constant.
B)The capacitor charges to its maximum value in two time constants.
C)The resistor and the capacitor share the applied voltage equally as a function of time.
D)The current flows through the circuit even after the capacitor is fully charged.
E)Once the capacitor is fully charged, there is no current in the circuit.

Question 45

A resistor and a capacitor are connected in series to an ideal battery of constant terminal voltage. At the moment contact is made with the battery, the voltage across the resistor is

A)greater than the battery's terminal voltage.
B)less than the battery's terminal voltage, but greater than zero.
C)equal to the battery's terminal voltage.
D)zero.

Question 46

Which of the following combinations would make a good analog ammeter?

A)a coil with a large resistance in parallel
B)a coil with a large resistance in series
C)a coil with a small resistance in parallel
D)a coil with a small resistance in series
E)More information is needed to answer the question.

Question 47

A resistor and a capacitor are connected in series to an ideal battery of constant terminal voltage. When this system reaches its steady-state, the voltage across the resistor is

A)greater than the battery's terminal voltage.
B)less than the battery's terminal voltage, but greater than zero.
C)equal to the battery's terminal voltage.
D)zero.

Question 48

If you connect two identical storage batteries together in parallel, and place them in a circuit, the combination will provide

A)twice the voltage and twice the total charge that one battery would.
B)twice the voltage and the same total charge that one battery would.
C)the same voltage and twice the total charge that one battery would.
D)half the voltage and half the total charge that one battery would.
E)half the voltage and the same total charge that one battery would.

Question 49

A galvanometer can be converted to an ammeter by the addition of a

A)small resistance in parallel.
B)large resistance in parallel.
C)small resistance in series.
D)large resistance in series.

Question 50

A resistor and a capacitor are connected in series to an ideal battery of constant terminal voltage. At the moment contact is made with the battery, the voltage across the capacitor is

A)greater than the battery's terminal voltage.
B)less than the battery's terminal voltage, but greater than zero.
C)equal to the battery's terminal voltage.
D)zero.

Question 51

A current reading is obtained by properly placing an ammeter in a circuit consisting of one resistor and one battery. As a result,

A)the voltage drop across the resistor increases.
B)the current flowing in the circuit increases.
C)the current flowing in the circuit decreases.
D)the current flowing in the circuit does not change.

Question 52

In order to construct a voltmeter from a galvanometer, one normally would

A)use a very small shunt resistor.
B)use a very large shunt resistor.
C)use a very small series resistor.
D)use a very large series resistor.

Question 53

An unknown resistor is wired in series with an ammeter, and a voltmeter is placed in parallel across the resistor only. This network is then connected to a battery. If one computes the value of the resistance by dividing the voltmeter reading by the ammeter reading, the value obtained

A)is less than the true resistance.
B)is greater than the true resistance.
C)is the true resistance.
D)could be any of the given answers. It depends on other factors.

Question 54

A 22-A current flows into a parallel combination of 4.0 Ω, 6.0 Ω, and 12 Ω resistors.
(a) What current flows through the 12-Ω resistor?
(b) What current flows through the 6.0-Ω resistor?
(c) What current flows through the 4.0-Ω resistor?

Question 55

Two resistors of 5.0 and 9.0 Ω are connected in parallel. A 4.0-Ω resistor is then connected in series with the parallel combination. A 6.0-V battery is then connected to the series-parallel combination.
(a) What is the current through the 4.0-Ω resistor?
(b) What is the current through the 5.0-Ω resistor?
(c) What is the current through the 9.0-Ω resistor?

Question 56

If you connect two identical storage batteries together in series ("+" to "-" to "+" to "-"), and place them in a circuit, the combination will provide

A)zero volts.
B)twice the voltage, and different currents will flow through each.
C)twice the voltage, and the same current will flow through each.
D)the same voltage, and different currents will flow through each.
E)the same voltage, and the same current will flow through each.

Question 57

An unknown resistor is wired in series with an ammeter, and a voltmeter is placed in parallel across both the resistor and the ammeter. This network is then placed across a battery. If one computes the value of the resistance by dividing the voltmeter reading by the ammeter reading, the value obtained

A)is less than the true resistance.
B)is greater than the true resistance.
C)is the true resistance.
D)could be any of the given answers. It depends on other factors.

Question 58

An RC circuit is connected across a DC voltage source through an open switch. The switch is closed at t = 0 s. Which of the following is a correct statement regarding this circuit?

A)The charge on the capacitor after four time constants is about 98% of the maximum value.
B)The charge on the capacitor after one time constant is about 25% of its maximum value.
C)The charge on the capacitor after one time constant is about 50% of its maximum value.
D)The voltage on the capacitor after two time constants is about 14% of the maximum value.
E)The voltage on this capacitor after two time constants is about 100% of its maximum value.

Question 59

An ideal ammeter is one that does not change the behavior of a circuit when it is properly used to measure current. The internal resistance of such a meter is

A)infinite.
B)dependent on the circuit.
C)0 Ω.
D)the same resistance as the circuit.
E)cannot be determined

Question 60

Decreasing the resistance of an ammeter's shunt resistance

A)allows it to measure a larger current at full scale deflection.
B)allows it to measure a smaller current at full scale deflection.
C)enables more current to pass directly through the galvanometer.
D)converts it to a voltmeter.

Question 61

FIGURE 26-14
A number of resistors are connected across points A and B as shown in Fig. 26-14. What is the equivalent resistance between points A and B?

A)4 Ω
B)6 Ω
C)8 Ω
D)10 Ω
E)12 Ω

Question 62

A 100-V DC signal is applied to a series circuit composed of four equal resistors 10 Ω each. What is the voltage across each resistor?

A)10 V
B)15 V
C)20 V
D)25 V
E)50 V

Question 63

Two unknown resistors A and B are connected together. When they are connected in series their combined resistance is 15 Ω. When they are connected in parallel, their combined resistance is 3.3 Ω. What are the resistances of A and B?

A)15 Ω and 5 Ω
B)5 Ω and 10 Ω
C)2.5 Ω and 5 Ω
D)32Ω and 20 Ω
E)10 Ω and 30Ω

Question 64

FIGURE 26-12
Refer the the circuit in Fig. 26-12 to answer the following:
(a) Determine the current in the 7-Ω resistor.
(b) Determine the current in the 8-Ω resistor.
(c) Determine the current in the 4-Ω resistor.

Question 65

Two resistors of 15 and 30 Ω are connected in parallel. If the combination is connected in series with a 9.0-V battery and a 20-Ω resistor, what is the current through the 15-Ω resistor?

A)0.10 A
B)0.13 A
C)0.20 A
D)0.26 A
E)0.32 A

Question 66

A 6-Ω resistor, an 8-Ω resistor, and a 24-Ω resistor are connected together. What is the minimum resistance that can be produced using all three resistors?

A)4 Ω
B)(1/24) Ω
C)3 Ω
D)(1/6) Ω
E)7 Ω

Question 67

When a 20.0-ohm resistor is connected across the terminals of a 12.0-V battery, the terminal voltage of the battery falls 0.30 V. What is the internal resistance of this battery?

A)3.60 Ω
B)1.56 Ω
C)0.98 Ω
D)0.30 Ω
E)0.51 Ω

Question 68

A 4-Ω resistor, an 8-Ω resistor, and a 24-Ω resistor are connected together. What is the maximum resistance that can be produced using all three resistors?

A)288 Ω
B)12 Ω
C)96 Ω
D)36 Ω
E)192 Ω

Question 69

A 2.0-Ω resistor is in series with a parallel combination of 4.0 Ω, 6.0 Ω, and 12 Ω. What is the equivalent resistance of this combination?

A)24 Ω
B)12 Ω
C)4.0 Ω
D)1.8 Ω
E)2.7 Ω

Question 70

A 14-A current flows into a series combination of a 3.0-Ω and a 4.0-Ω resistor. What is the voltage drop across the 4.0-Ω resistor?

A)24 V
B)38 V
C)42 V
D)56 V
E)98 V

Question 71

Two 4.0-Ω resistors are connected in parallel, and this combination is connected in series with 3.0 Ω. What is the effective resistance of this combination?

A)1.2 Ω
B)5.0 Ω
C)7.0 Ω
D)8.0 Ω
E)11 Ω

Question 72

FIGURE 26-11
Refer to the circuit in Fig. 26-11, to answer the following:
(a) Determine the current in the 1-Ω resistor.
(b) Determine the current in the 3-Ω resistor.
(c) Determine the current in the 4-Ω resistor.

Question 73

Three resistors of 12, 12, and 6.0 Ω are connected in parallel. A 12-V battery is connected to the combination. What is the current through the 6.0-Ω resistor?

A)1.0 A
B)2.0 A
C)3.0 A
D)4.0 A
E)5.0 A

Question 74

When a 100-Ω resistor is connected to a battery of emf E and internal resistance r, the battery delivers a power P = 0.794 W. When a 200 Ω resistance is connected to same battery it delivers a power P = 0.401 W. What are the emf and internal resistance of the battery?

A)E = 10 V, r = 5 Ω
B)E = 4.5 V, r = 4 Ω
C)E = 18 V, r = 4 Ω
D)E = 9 V, r = 2 Ω
E)E = 12 V, r = 6 Ω

Question 75

FIGURE 26-13
Five equal resistors, of value 2.0 Ω each, are connected as shown in Fig. 26-13. What is the equivalent resistance of this circuit?

A)1.0 Ω
B)10.0 Ω
C)2.0 Ω
D)6.0 Ω
E)0.40 Ω

Question 76

What is the maximum current that can be drawn from a 1.50-V battery with an internal resistance of 0.30 ohm?

A)2.5 A
B)5.0 A
C)0.45 A
D)0.20 A
E)4.5 A

Question 77

FIGURE 26-15
A number of resistors are connected across points A and B as shown in Fig. 26-15. What is the equivalent resistance between points A and B?

A)4 Ω
B)6 Ω
C)8 Ω
D)10 Ω
E)12 Ω

Question 78

Four resistors of 12, 3.0, 5.0, and 4.0 Ω are connected in parallel. A 12-V battery is connected to the combination. What is the current through the battery?

A)10 A
B)5.0 A
C)2.5 A
D)0.50 A
E)0.25 A

Question 79

A 14-A current flows into a series combination of a 3.0-Ω and a 4.0-Ω resistor. What is the voltage drop across the 3.0-Ω resistor?

A)42 V
B)56 V
C)98 V
D)38 V
E)24 V

Question 80

Three resistors of 12, 12, and 6.0 Ω are connected in series. A 12-V battery is connected to the combination. What is the current through the battery?

A)0.10 A
B)0.20 A
C)0.30 A
D)0.40 A
E)0.50 A