# Quiz 19: Electric Currents and Circuits

Physics & Astronomy

Q 1Q 1

The current in an electron beam in a cathode-ray tube is measured to be 280 µA. How many electrons hit the screen in 50 s? (e = 1.6 10

^{}^{19}C) A) 2.2 10^{11 }electrons B) 8.8 10^{16}electrons C) 8.8 10^{15}electrons D) 2.2 10^{15}electronsFree

Multiple Choice

B

Q 2Q 2

A wire carries a steady current of 0.1 A over a period of 200 s. What total charge passes through the wire in this time interval?
A) 2 C
B) 200 C
C) 0.005 C
D) 20 C

Free

Multiple Choice

D

Q 3Q 3

In a certain material there is a current of 16 A flowing through a surface to the left, and there is an equal amount of positive and negative charge passing through the surface producing the current. How much negative charge passes through the surface?
A) 16 C/s toward the left
B) 16 C/s toward the right
C) 8 C/s toward the right
D) 8 C/s toward the left

Free

Multiple Choice

C

Q 4Q 4

A lightbulb drawing a current of 0.60 A is run for 2.0 hours. How many electrons pass through the bulb during this process?
A)
B)
C)
D)

Free

Multiple Choice

Q 5Q 5

A 300-A·h battery can deliver how many coulombs starting from a full charge?
A) 4.8 10

^{3}B) 4.3 10^{4}C) 7.2 10^{5}D) 1.1 10^{6}Free

Multiple Choice

Q 6Q 6

A 12.6-V battery supplies a 2.0-A current for 2.0 minutes. What is the work done by the battery during this process?
A) 0 J
B) 3.0 10

^{3}J C) 2.5 10^{2}J D) 1.5 10^{4}JFree

Multiple Choice

Q 7Q 7

If the current in a wire is halved, what effect does this have on the electron drift velocity in the wire?
A) It decreases by a factor of two.
B) It increases by a factor of four.
C) It stays the same.
D) It doubles.

Free

Multiple Choice

Q 8Q 8

Wire A and Wire B are each carrying the same current. If the diameter of Wire A is half that of Wire B, how does the drift velocity v

_{dA}in Wire A compare to that in Wire B? A) v_{dA}= 4 v_{dB}B) v_{dA}= 2 v_{dB}C) v_{dA}= v_{dB}/2 D) v_{dA}= v_{dB}/4Free

Multiple Choice

Q 9Q 9

If a metallic wire of cross-sectional area 3.0 10

^{}^{6}m^{2}carries a current of 9.1 A and has a mobile charge density of 4.24 10^{28}carriers/m^{3}, what is the average drift velocity of the mobile charge carriers? (charge value = 1.6 10^{}^{19}C) A) 3.4 10^{3}m/s B) 1.7 10^{3}m/s C) 4.5 10^{}^{4}m/s D) 1.5 10^{}^{4}m/sFree

Multiple Choice

Q 10Q 10

The size of the electric current in a electrical conductor is a function of which of the following?
A) conductor cross sectional area
B) velocity of charge carriers
C) density of charge carriers
D) All of these choices are valid.

Free

Multiple Choice

Q 11Q 11

When an electric current exists within a conducting wire, which of the following statements describes the condition of any accompanying electric field?
A) must be perpendicular to current flow
B) must be parallel to current flow
C) must be zero
D) must be anti-parallel (opposite direction) to current flow

Free

Multiple Choice

Q 12Q 12

When you flip a switch to turn on a light, the delay before the light turns on is determined by:
A) the speed of the electric field moving in the wire.
B) the drift speed of the electrons in the wire.
C) the number of electron collisions per second in the wire.
D) none of these, since the light comes on instantly.

Free

Multiple Choice

Q 13Q 13

You measure a 20.0-V potential difference across a 5.00- resistor. What is the current flowing through it?
A) 5.00 A
B) 4.00 A
C) 100 A
D) 1.00 A

Free

Multiple Choice

Q 14Q 14

The unit of electric current, the ampere, is equivalent to which of the following?
A) V/
B) V/s
C) m
D) V

Free

Multiple Choice

Q 15Q 15

A metallic conductor has a resistivity of 18 10

^{}^{6}m. What is the resistance of a piece that is 15 m long and has a uniform cross sectional area of 6.0 10^{}^{6}m^{2}? A) 0.056 B) 45 C) 90 D) 160 Free

Multiple Choice

Q 16Q 16

Two cylindrical resistors are made of the same material and have the same resistance. The resistors, R

_{1}and R_{2}, have different radii, r_{1}and r_{2}, and different lengths, L_{1}and L_{2}. Which of the following relative values for radii and lengths would result in equal resistances? A) r_{1 }=_{ }r_{2}and 4L_{1}_{ }= L_{2}B) r_{1 }=_{ }r_{2}and L_{1 }= 2L_{2}C) 2r_{1 }=_{ }r_{2}and 4L_{1}_{ }= L_{2}D) 2r_{1 }=_{ }r_{2}and L_{1}_{ }= 2L_{2}Free

Multiple Choice

Q 17Q 17

How long is a wire made from 200 cm

^{3}of copper if its resistance is 8.5 ohms? The resistivity of copper is 1.7 10^{-5}·m. A) 10 m B) 2.2 10^{2}m C) 7.1 m D) 3.0 10^{3}mFree

Multiple Choice

Q 18Q 18

Two wires with the same resistance have the same diameter but different lengths. If wire 1 has length L

_{1}and wire 2 has length L_{2}, how do L_{1}and L_{2}compare if wire 1 is made from copper and wire 2 is made from aluminum? The resistivity of copper is 1.7 10^{-5}·m and the resistivity of aluminum is 2.82 10^{-5}·m. A) L_{1}= 0.36 L_{2}B) L_{1}= 2.8 L_{2}C) L_{1}= 0.60 L_{2}D) L_{1}= 1.7 L_{2}Free

Multiple Choice

Q 19Q 19

A 0.10-m long metal rod has a radius of 1.0 cm and a resistance of 3.2 10

^{}^{5}. What is the resistivity of the metal? A) 5.0 10^{}^{8}m B) 160 10^{}^{8}m C) 10 10^{}^{8}m D) 1.6 10^{}^{8 }mFree

Multiple Choice

Q 20Q 20

A Nichrome wire has a radius of 0.50 mm and a resistivity of 1.5 10

^{}^{6}m. If the wire carries a current of 1.0 A, what is the potential difference per unit length along this wire? A) 1.9 V/m B) 0.95 V/m C) 1.6 V/m D) 0.003 V/mFree

Multiple Choice

Q 21Q 21

A copper cable needs to carry a current of 200 A with a power loss of only 1.5 W/m. What is the required radius of the copper cable? (The resistivity of copper is 1.7 10

^{}^{8}m.) A) 4.0 cm B) 0.21 cm C) 0.85 cm D) 1.2 cmFree

Multiple Choice

Q 22Q 22

Three wires of the same diameter and length are made from three different metals: copper ( ), aluminum ( ), and silver ( ). Which wire has the least resistance?
A) the aluminum wire
B) the silver wire
C) the copper wire
D) Since insufficient information is given to find the resistance of each wire, one cannot find the answer.

Free

Multiple Choice

Q 23Q 23

A wire of length L is uniformly stretched to triple its original length.By what factor does its resistance change?
A) 1, i.e., no change
B) 3
C) 9
D)

Free

Multiple Choice

Q 24Q 24

A length L of wire has a voltage V across its ends while a current I runs through the wire. If a voltage 3V were applied to another length of this same wire from the same coil and the same current were found to run through it, what is the length of this second wire?
A)
B)
C)
D)

Free

Multiple Choice

Q 25Q 25

If a light bulb has half the resistance of a 50-W lightbulb, what would be its wattage? Assume both bulbs are attached to the same 120-V circuit.
A) More information is needed.
B) 25 W
C) 200 W
D) 100 W

Free

Multiple Choice

Q 26Q 26

If a 9.0-V battery, with negligible internal resistance, and an 27- resistor are connected in series, what is the amount of electrical energy transformed to heat per coulomb of charge that flows through the circuit?
A) 0.50 J
B) 9.0 J
C) 3.0 J
D) 72 J

Free

Multiple Choice

Q 27Q 27

A 100-W light bulb is in a socket supplied with 120 V. What is the current in the bulb?
A) 7200 A
B) 0.83 A
C) 1.4 A
D) 0.50 A

Free

Multiple Choice

Q 28Q 28

A resistor is connected to a battery with negligible internal resistance. If you replace the resistor with one that has quadruple the resistance, by what factor does the power dissipated in the circuit change?
A) 0.25
B) 4.0
C) 2.0
D) 0.50

Free

Multiple Choice

Free

Multiple Choice

Q 30Q 30

The unit for rate of energy transformation, the watt, in an electric circuit is equivalent to which of the following?
A) A
B) V/s
C) V/
D) VA

Free

Multiple Choice

Q 31Q 31

If a 500-W heater carries a current of 2.00 A, what is the voltage across the ends of the heating element?
A) 2000 V
B) 125 V
C) 0.008 V
D) 250 V

Free

Multiple Choice

Q 32Q 32

If a lamp has resistance of 120 when it operates at 200 W, what is the applied voltage?
A) 120 V
B) 220 V
C) 110 V
D) 155 V

Free

Multiple Choice

Q 33Q 33

A light bulb, sold as long-lasting, is rated 120 W at 130 V. The "increased" lifetime comes from using it at 120 V. Assuming negligible change in resistance at the different voltage, what is its power consumption at 120 V?
A) 92 W
B) 102 W
C) 108 W
D) 85 W

Free

Multiple Choice

Q 34Q 34

An electric clothes dryer draws 20 A at 220 V. If the clothes put into the dryer have a mass of 7.0 kg when wet and 3.0 kg dry, how long does it take to dry the clothes? (Assume all heat energy goes into vaporizing water, L

_{v}= 2.26 10^{6}J/kg.) A) 55 min B) 26 min C) 16 min D) 34 minFree

Multiple Choice

Q 35Q 35

Ten coulombs of charge start from the negative terminal of a battery, flow through the battery and then leave the positive terminal through a wire, flow through a resistor, and then return to the starting point on this closed circuit. In this complete process, the ten coulombs:
A) receive heat energy from the resistor.
B) do positive work on the battery.
C) have a net loss of potential energy.
D) have no net change in potential energy.

Free

Multiple Choice

Q 36Q 36

Which process will double the power given off by a resistor?
A) doubling the current while making the voltage half as big
B) doubling the current while doubling the resistance
C) doubling the current by doubling the voltage
D) doubling the current by making a resistance half as big

Free

Multiple Choice

Q 37Q 37

A water pump draws about 4.4 A when connected to 240 V. What is the cost (with electrical energy at 9 cents per kWh) of running the pump for 10 h?
A) 82 cents
B) 8.0 cents
C) 95 cents
D) 15 cents

Free

Multiple Choice

Q 38Q 38

A high-voltage transmission line carries 500 A at 700,000 V. What is the power carried by the line?
A) 100 MW
B) 350 MW
C) 700 MW
D) 70 MW

Free

Multiple Choice

Q 39Q 39

A high-voltage transmission line carries 500 A at 700 kV for a distance of 100 miles. If the resistance in the wire is 1 /mile, what is the power loss due to resistive losses?
A) 250 MW
B) 2.5 kW
C) 25 MW
D) 25 kW

Free

Multiple Choice

Q 40Q 40

An electric car is designed to run off a bank of 12-V batteries with total energy storage of 6.0 10

^{7}J. If the electric motor draws 6000 W in moving the car at a steady speed of 10 m/s, how far will the car go before it is "out of juice?" A) 150 km B) 50 km C) 100 km D) 25 kmFree

Multiple Choice

Q 41Q 41

A solar panel measures 80 cm 50 cm. In direct sunlight, the panel delivers 4.8 A at 15 V. If the intensity of sunlight is 1000 W/m

^{2}, what is the efficiency of the solar panel in converting solar energy into electrical energy? A) 12% B) 24% C) 18% D) 6.0%Free

Multiple Choice

Q 42Q 42

An 10.0- resistor is dissipating 100 watts. What are the current through it and the difference of potential across it?
A) 31.6 A, 3.16 V
B) 10.0 A, 3.16 V
C) 3.16 A, 31.6 V
D) 3.16 A, 10.0 V

Free

Multiple Choice

Q 43Q 43

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) This cannot be found until it is known which resistor is in series with the parallel pair.
B) all three resistors in series
C) two of the resistors in parallel with the third resistor in series with the parallel pair
D) all three resistors in parallel

Free

Multiple Choice

Q 44Q 44

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

Free

Multiple Choice

Q 45Q 45

When a 24.0- resistor is connected across a 12.0-V battery, a current of 410 mA flows. What is the internal resistance of the battery?
A) 29.3
B) 0.9
C) 5.3
D) 0.02

Free

Multiple Choice

Q 46Q 46

When a 24.0- resistor is connected across a 12.0-V battery, a current of 410 mA flows. What is the resulting terminal voltage of the battery?
A) 11.6 V
B) 9.8 V
C) 0.4 V
D) 12.0 V

Free

Multiple Choice

Q 47Q 47

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})^{}^{1}C) I_{T}= (1/I_{1}+ 1/I_{2 }+ 1/I_{3}) D) I_{T}= I_{1}= I_{2}= I_{3}Free

Multiple Choice

Q 48Q 48

Three resistors connected in series have individual voltages labeled V

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

Multiple Choice

Free

Multiple Choice

Q 50Q 50

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 voltage across R equals the voltage across R_{1}. B) The current through R equals the current through 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 51Q 51

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_{3}C) R_{2}D) All are equal in power dissipation.Free

Multiple Choice

Q 52Q 52

Four 8.0- resistors are connected in parallel. What is their equivalent resistance?
A) 4.0
B) 0.50
C) 2.0
D) 32

Free

Multiple Choice

Q 53Q 53

Three 3.0- resistors are connected in parallel to a 12.0-V battery. What is the current in any one of the resistors?
A) 0.75 A
B) 12 A
C) 4.0 A
D) 1.3 A

Free

Multiple Choice

Q 54Q 54

Three resistors connected in parallel have individual values of 4.0, 6.0, and 10.0 , respectively. If this combination is connected in series with a 12-V battery and a 2.0- resistor, what is the current in the 6.0- resistor?
A) 0.98 A
B) 16 A
C) 0.59 A
D) 11 A

Free

Multiple Choice

Q 55Q 55

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}= (1/I_{1}+ 1/I_{2}+ 1/I_{3}) B) I_{T}= I_{1}= I_{2}= 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 56Q 56

Three resistors connected in parallel have the individual voltages labeled V

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

Multiple Choice

Q 57Q 57

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}= (1/R_{1}+ 1/R_{2}+ 1/R_{3}) B) R_{T}_{ }= R_{1}= R_{2}= 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 58Q 58

Two resistors of values 6.0 and 12.0 are connected in parallel. This combination in turn is hooked in series with an 8.0- resistor and a 24-V battery. What is the current in the 12- resistor?
A) 1.3 A
B) 4.0 A
C) 12 A
D) 0.67 A

Free

Multiple Choice

Q 59Q 59

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

Free

Multiple Choice

Q 60Q 60

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

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

Multiple Choice

Q 61Q 61

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) R is greater than R_{1}. C) The power given off by R equals the power given off by R_{1}. D) The voltage across R equals the voltage across R_{1}.Free

Multiple Choice

Q 62Q 62

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

Free

Multiple Choice

Q 63Q 63

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

Free

Multiple Choice

Free

Multiple Choice

Q 65Q 65

If = 20 V, at what rate is thermal energy being generated in the 40- resistor?
A) 26 W
B) 1.6 W
C) 3.3 W
D) 15 W

Free

Multiple Choice

Q 66Q 66

If = 9.0 V, what is the current in the 30- resistor?
A) 0.30 A
B) 0.26 A
C) 0.10 A
D) 0.20 A

Free

Multiple Choice

Q 67Q 67

Consider the circuit shown in the figure. What power is dissipated by the top 5- resistor?
A) 14 W
B) 112 W
C) 17 W
D) 52 W

Free

Multiple Choice

Q 68Q 68

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_{2}B) R_{1}C) All have the same current. D) R_{3}Free

Multiple Choice

Q 69Q 69

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

Free

Multiple Choice

Q 70Q 70

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

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

Multiple Choice

Q 71Q 71

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 left 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 72Q 72

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 left 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 76Q 76

Four 1.5-volt AA batteries in series power a transistor radio. If the batteries hold a total charge of 440 C, how long will they last if the radio has a resistance of 200 ?
A) 4.1 h
B) 2.2 h
C) 1.1 h
D) 13 h

Free

Multiple Choice

Q 77Q 77

In the circuit segment shown if I = 8.0 mA and Q = 75 µC, what is the potential difference, V

_{A}- V_{B}? A) 35 V B) +15 V C) -15 V D) +35 VFree

Multiple Choice

Q 78Q 78

If I = 1.0 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) 1.0 mC, left plate is positive B) 3.5 mC, right plate is positive C) 3.5 mC, left plate is positive D) 1.0 mC, right plate is positiveFree

Multiple Choice

Q 79Q 79

Five resistors each have resistance R. Three of the resistors are connected in series and this combination is then connected in parallel with the two other resistors which have been connected in series with each other. What is the equivalent resistance for this arrangement?
A)
B)
C)
D)

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Multiple Choice

Q 80Q 80

A battery has an internal resistance . Connecting a wire of negligible resistance between the terminals of the battery draws the maximum current from this battery. If instead a resistor is connected between the terminals, a smaller current is produced. What value resistor placed across the terminals would result in the current produced to be half of ?
A)
B)
C)
D)

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Multiple Choice

Q 81Q 81

A 100-W bulb and a 40-W bulb, each designed for an applied voltage of 120 V, are connected in series across a 120-V source. What are the voltages across the 100-W bulb and across the 40-W bulb?
A) 86 V, 34 V
B) 30 V, 90 V
C) 90 V, 30 V
D) 34 V, 86 V

Free

Multiple Choice

Q 82Q 82

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 parallel with each other
B) the capacitor in series with both resistors in series with each other
C) the capacitor in series with the higher value resistor
D) the capacitor in series with the lower value resistor

Free

Multiple Choice

Q 83Q 83

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 the lower value capacitor
C) the resistor in series with the larger value capacitor
D) the resistor in series with both capacitors in parallel with each other

Free

Multiple Choice

Q 84Q 84

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 parallel placed in series with both resistors in parallel
B) both capacitors in series placed in series with both resistors in series
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

Free

Multiple Choice

Q 85Q 85

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

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Multiple Choice

Q 86Q 86

A 10-V battery is connected in series with the following: a 2-F capacitor, a 2- 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) 5 A, zero V
B) zero A, zero V
C) zero A, 10 V
D) 5 A, 10 V

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Multiple Choice

Q 87Q 87

A circuit contains a 6.0-V battery, a 4.0- 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) 1.5 A
B) 10 A
C) 0.75 A
D) zero

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Multiple Choice

Q 88Q 88

A circuit contains a 6.0-V battery, a 4.0- 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) 2.4 C
B) zero
C) 3.6 C
D) 0.10 C

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Multiple Choice

Q 89Q 89

A 1000-V battery, a 3000- resistor, and a 0.50-F capacitor are connected in series with a switch. The time constant for such a circuit, designated by the Greek letter, , 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 seconds after the switch has been closed?
A) 0.14 A
B) 0.12 A
C) 0.32 A
D) 0.21 A

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Multiple Choice

Q 90Q 90

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 3.7 V. This time can be decreased for this circuit by increasing:
A) the size of the time constant.
B) the size of the resistor.
C) the size of the capacitor.
D) None of these choices.

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Multiple Choice

Q 91Q 91

A series RC circuit has a time constant of 1.5 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 3.0 s after the switch is closed?
A) 0.48 C
B) 0.86 C
C) 0.43 C
D) 0.99 C

Free

Multiple Choice

Q 92Q 92

In circuits involving resistors and capacitors the quantity 63% often arises. Which of the following is equivalent to this quantity?
A)
B)
C)
D)

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Multiple Choice

Q 93Q 93

A series RC circuit consists of a battery, a switch, a resistor, and a capacitor. In terms of the time constant of this circuit, how long after the switch is closed does the current in the circuit reach half of its maximum value?
A) 0.500
B) 1.50
C) 0.693
D) 2.00

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Multiple Choice

Q 94Q 94

An RC circuit with resistance and capacitance has a time constant . Which of the following additions to the circuit would result in the time constant doubling?
A) a capacitor with capacitance in series with the original
B) a capacitor with capacitance in series with the original
C) a capacitor with capacitance in parallel with the original
D) a capacitor with capacitance in parallel with the original

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Multiple Choice

Q 95Q 95

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 infinite.
B) infinite and zero.
C) zero and zero.
D) infinite and infinite.

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Multiple Choice

Q 96Q 96

To measure the current through and the voltage across a resistor in a circuit, you should place the ammeter in _____ with the resistor and the voltmeter in _____ with the resistor.
A) series, series
B) parallel, series
C) parallel, parallel
D) series, parallel

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Multiple Choice

Q 97Q 97

In order for a circuit to respond quickly, its time constant should be short. In a circuit involving resistance and capacitance, which of the following choices would result in the shortest time constant?
A) R = 75 , C = 75 F
B) R = 200 , C = 200 F
C) R = 300 , C = 75 F
D) R = 100 , C = 30 F

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Multiple Choice

Q 98Q 98

In a circuit involving resistance and capacitance, which of the following choices would result in the longest time constant?
A) R = 100 , C = 30 F
B) R = 300 , C = 150 F
C) R = 75 , C = 75 F
D) R = 200 , C = 200 F

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Multiple Choice

Q 99Q 99

A defibrillator has a 130-F capacitor charged to 2000 V and an internal resistance of 30 . If the resistance of the path of the discharge through the patient is 170 , how much energy is delivered to the patient upon complete discharge of the capacitor?
A) 170 J
B) 30 J
C) 220 J
D) 240 J

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Multiple Choice

Q 100Q 100

The following three appliances are connected to a 120-V house circuit: i) toaster, 1200 W, ii) coffee pot, 750 W, and iii) microwave, 1000 W. If all were operated at the same time, what total current would they draw?
A) 5.0 A
B) 25 A
C) 23 A
D) 6.0 A

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Multiple Choice

Q 101Q 101

What is the maximum number of 60-W light bulbs you can connect in parallel in a 120-V home circuit without tripping the 20-A circuit breaker?
A) 3600
B) 59
C) 11
D) 39

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Multiple Choice

Q 102Q 102

A hair dryer draws 1500 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) 23.3 A
B) 20.8 A
C) 36.7 A
D) 19.4 A

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Multiple Choice

Q 103Q 103

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) Nothing electrical, it is for mechanical sturdiness.
C) It connects the case of the appliance directly to ground for safety purposes.
D) It lets the appliance run if the neutral wire breaks.

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Multiple Choice

Q 104Q 104

A 22- platinum wire at 20°C with a temperature coefficient of resistivity of 3.9 10

^{}^{3}(°C)^{}^{1}will have what resistance at 100°C? A) 29 B) 20 C) 26 D) 14 Free

Multiple Choice

Q 105Q 105

A metal wire has a resistance of 25.00 under room temperature conditions of 25°C. When the wire is heated to 85°C the resistance increases by 1.95 . What is the temperature coefficient of resistivity of this metal?
A) 1.3 10

^{}^{3}(°C)^{}^{1}B) 1.5 10^{}^{3}(°C)^{}^{1}C) 5.0 10^{}^{4}(°C)^{}^{1}D) 2.5 10^{}^{3}(°C)^{}^{1}Free

Multiple Choice

Q 106Q 106

A metal wire has a resistance of 10.00 at a temperature of 20.0°C. If the same wire has a resistance of 10.55 at 90°C, what is the resistance when its temperature is 0.0°C?
A) 13.8
B) 9.69
C) 9.84
D) 0.70

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Multiple Choice

Q 107Q 107

A certain material is in a room at 27°C. If the absolute temperature (K) of the material is tripled, its resistance quadruples. (Water freezes at 273 K.) What is the value for , the temperature coefficient of resistivity?
A) 0.0050 (°C)

^{}^{1}B) 0.0025 (°C)^{}^{1}C) 1 (°C)^{}^{1}D) 3 (°C)^{}^{1}Free

Multiple Choice

Q 108Q 108

A tungsten wire is used to determine the melting point of indium. The resistance of the tungsten wire is 6.000 at 20°C and increases to 9.700 as the indium starts to melt.

_{tungsten}= 4.50 10^{}^{3}(°C)^{}^{1}. What is the melting temperature of indium? A) 351°C B) 731°C C) 132°C D) 157°CFree

Multiple Choice

Q 109Q 109

The resistance of a platinum wire is to be calibrated for low-temperature work. A platinum wire with resistance 2.000 at 20°C is immersed in liquid nitrogen at 77 K (196°C). If the temperature response of the platinum wire is linear, what is the expected resistance of the platinum wire at 196°C? [

_{platinum }= 3.92 10^{}^{3}(°C)^{}^{1}]. A) 0.153 B) 1.768 C) 3.69 D) 0.307 Free

Multiple Choice

Q 110Q 110

Carbon has a negative temperature coefficient of resistance of -0.5 10

^{-3}(°C)^{}^{1}. What temperature increase would result in a resistance decrease of 3% for a carbon resistor? A) 60°C B) 100°C C) 20°C D) 40°CFree

Multiple Choice

Q 111Q 111

A light bulb with a tungsten filament is attached to a source of variable voltage. As the voltage is increased on the bulb,
A) the bulb's resistance decreases.
B) the bulb's resistance increases.
C) the power dissipated remains constant.
D) the current in the bulb decreases.

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Multiple Choice

Q 112Q 112

A superconducting wire's chief characteristic is which of the following?
A) no resistance
B) a large cross sectional area
C) an extremely great length
D) an extremely high temperature

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Multiple Choice

Q 113Q 113

When a superconductor's temperature drops below the critical temperature, its resistance:
A) equals that of a semiconductor of equal dimensions.
B) drops to zero.
C) reduces to one half.
D) increases by two.

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Multiple Choice

Q 114Q 114

Consider some material that has been cooled until it has become a superconductor. If it is cooled even further its resistance will:
A) stay constant and non-zero.
B) increase.
C) decrease.
D) None of these choices.

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Multiple Choice

Q 115Q 115

When current is flowing in a superconductor, which statement is not true?
A) The resistance is zero.
B) No power is given off in the form of heat.
C) A battery is needed to keep the current going.
D) Electrical charges are moving.

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Multiple Choice