Question 1

Of the common battery sizes AAA,AA,C,and D,which provides the highest emf?

Accepted Answer

A)  AAA 
B)  AA 
C)  C 
D)  D 
E)  all have the same emf 
A)  AAA 
B)  AA 
C)  C 
D)  D 
E)  all have the same emf

Question 2

In the diagram,if the current through R1 is 5 A up and if the current through R3 is 3 A up, what is the current in R2?

Accepted Answer

A)  8 A up 
B)  8 A down 
C)  2 A up 
D)  2 A down 
E)  more information is needed 
A)  8 A up 
B)  8 A down 
C)  2 A up 
D)  2 A down 
E)  more information is needed

Question 3

Copper has 8.5 $\times$ 1028 current carrying electrons per m3. A copper wire of radius 0.15 mm carries a current of 17 mA.What is the average drift velocity for the electrons?

Accepted Answer

A)  2.7 $\times$ 10-9 m/s 
B)  56 $\times$ 10-6 m/s 
C)  18 $\times$ 10-6 m/s 
D)  more information is needed for this calculation 
A)  2.7 $\times$ 10-9 m/s 
B)  56 $\times$ 10-6 m/s 
C)  18 $\times$ 10-6 m/s 
D)  more information is needed for this calculation

Question 4

A capacitor in an RC circuit is charged,storing energy 1.25 mJ.What is the time required to discharge this capacitor,as compared to the time required to discharge an identical capacitor in an identical RC circuit which has stored 2.5 mJ?

Accepted Answer

A)  twice the time 
B)  half the time 
C)  the same time 
D)  the answer depends on the values of R and C. 
A)  twice the time 
B)  half the time 
C)  the same time 
D)  the answer depends on the values of R and C.

Question 5

A series circuit consists of a 12.0 V source of emf, a 2.00 mF capacitor,a 1000 $\Omega$ resistor, and a switch.What is the time constant for this circuit?

Accepted Answer

A)  10.0 s 
B)  2.00 s 
C)  0.693 s 
D)  0.0825 s 
E)  1.00 ms 
A)  10.0 s 
B)  2.00 s 
C)  0.693 s 
D)  0.0825 s 
E)  1.00 ms

Question 6

In a series circuit consisting of a 12.0 emf,a 2.00 mF capacitor,a 1.00 k$\Omega$ resistor and a switch,what is the voltage across the capacitor at a time $\tau$ after the switch is closed?

Accepted Answer

A)  .632 V 
B)  6.32 V 
C)  7.58 V 
D)  8.65 V 
A)  .632 V 
B)  6.32 V 
C)  7.58 V 
D)  8.65 V

Question 7

An electron beam contains 1.5 $\times$ 1017 electrons per m3 and is confined to circular region of diameter 0.025 mm.The electrons in the beam are extremely energetic,and travel at nearly the speed of light.What is the current in the beam?

Accepted Answer

A)  1.4 A 
B)  3.5 mA 
C)  350 mA 
D)  14 mA 
A)  1.4 A 
B)  3.5 mA 
C)  350 mA 
D)  14 mA

Question 8

One hundred meters of 2.00 mm diameter wire has a resistance of 0.532 $\Omega$.What is the resistivity of the material from which the wire is made?

Accepted Answer

A)  1.59 $\times$ 10 8 $\Omega$ m 
B)  1.67 $\times$ 10 8 $\Omega$ m 
C)  2.35 $\times$ 10 8 $\Omega$m 
D)  2.65 $\times$ 10 8 $\Omega$ m 
E)  5.40 $\times$ 10 8 $\Omega$·m 
A)  1.59 $\times$ 10 8 $\Omega$ m 
B)  1.67 $\times$ 10 8 $\Omega$ m 
C)  2.35 $\times$ 10 8 $\Omega$m 
D)  2.65 $\times$ 10 8 $\Omega$ m 
E)  5.40 $\times$ 10 8 $\Omega$·m

Question 9

Four 12 $\Omega$ resistors are connected together.Which of the following resistances cannot be formed using all 4 resistors?

Accepted Answer

A)  48 $\Omega$ 
B)  9.0 $\Omega$ 
C)  12 $\Omega$ 
D)  60 $\Omega$ 
E)  20 $\Omega$ 
A)  48 $\Omega$ 
B)  9.0 $\Omega$ 
C)  12 $\Omega$ 
D)  60 $\Omega$ 
E)  20 $\Omega$

Question 10

A series circuit consists of a 12.0 V source of emf,a 2.00 mF capacitor,a 1000 $\Omega$ resistor,and a switch.When the switch is closed,how long does it take for the current to reach one-tenth its maximum value?

Accepted Answer

A)  0.693 s 
B)  2.30 s 
C)  4.61 s 
D)  9.00 s 
E)  18.0 s 
A)  0.693 s 
B)  2.30 s 
C)  4.61 s 
D)  9.00 s 
E)  18.0 s

Question 11

In an RC circuit with an initially uncharged capacitor,the time constant is the time that is required for the charge on the capacitor to reach what percentage of its final value?

Accepted Answer

A)  50% 
B)  37% 
C)  100% 
D)  63% 
E)  90% 
A)  50% 
B)  37% 
C)  100% 
D)  63% 
E)  90%

Question 12

A flashlight,which uses two 1.5 V batteries in series,is turned on for 2.0 minutes.If the current in the flashlight is 100 mA,what is the energy dissipated?

Accepted Answer

A)  12 J 
B)  9.0 J 
C)  72 J 
D)  36 J 
E)  18 J 
A)  12 J 
B)  9.0 J 
C)  72 J 
D)  36 J 
E)  18 J

Question 13

If R1 = 6.0 $\Omega$, R2 = 8.0 $\Omega$, R3 = 2.0 $\Omega$, $\varepsilon$1 = 4.0 V, and $\varepsilon$2 = 14 V,what is the power supplied to the circuit by $\varepsilon$1?

Accepted Answer

A)  4.0 W 
B)  8.0 W 
C)  12 W 
D)  16 W 
E)  20 W 
A)  4.0 W 
B)  8.0 W 
C)  12 W 
D)  16 W 
E)  20 W

Question 14

In the diagram,each resistor is 3 ohms and the battery is 9 volts.What is the current through the middle resistor?

Accepted Answer

A)  3 A to the right 
B)  3 A to the left 
C)  9 A to the right 
D)  9 A to the left 
E)  1 A to the left 
A)  3 A to the right 
B)  3 A to the left 
C)  9 A to the right 
D)  9 A to the left 
E)  1 A to the left

Question 15

A potential difference of 12.4 V is placed across a 4.1 $\Omega$ resistor.What is the current in the resistor?

Accepted Answer

A)  51 A 
B)  3.0 A 
C)  0.33 A 
D)  16A 
E)  8.3 A 
A)  51 A 
B)  3.0 A 
C)  0.33 A 
D)  16A 
E)  8.3 A

Question 16

A 1.56-V battery has an internal resistance of 0.120 $\Omega$.What is the maximum current that can be drawn from this battery?

Accepted Answer

A)  infinite (or at least 1000's of amps) 
B)  1.56 A 
C)  0.190 A 
D)  13.0 A 
E)  7.50 A 
A)  infinite (or at least 1000's of amps) 
B)  1.56 A 
C)  0.190 A 
D)  13.0 A 
E)  7.50 A

Question 17

Four 12 $\Omega$ resistors are connected together.What is the least resistance that can be attained with these resistors?

Accepted Answer

A)  12 $\Omega$ 
B)  6.0 $\Omega$ 
C)  3.0 $\Omega$ 
D)  2.0 $\Omega$ 
E)  1.0 $\Omega$ 
A)  12 $\Omega$ 
B)  6.0 $\Omega$ 
C)  3.0 $\Omega$ 
D)  2.0 $\Omega$ 
E)  1.0 $\Omega$

Question 18

A 1000 $\Omega$ resistor is in a circuit with 30.0 mA flowing through it.A voltmeter with internal resistance 1000 $\Omega$ is used to measure the voltage across the resistor.What is the reading from the voltmeter if 30.0 mA still flows in the circuit?

Accepted Answer

A)  30.0 V 
B)  29.9 V 
C)  27.0 V 
D)  15.0 V 
E)  3.00 V 
A)  30.0 V 
B)  29.9 V 
C)  27.0 V 
D)  15.0 V 
E)  3.00 V

Question 19

A variable resistor has a voltage of 12.0 V placed across it.If the resistance is increased 20%,what happens to the current through it?

Accepted Answer

A)  it increases 20% 
B)  it increases 25% 
C)  it decreases 20% 
D)  it decreases 25% 
E)  it decreases 17% 
A)  it increases 20% 
B)  it increases 25% 
C)  it decreases 20% 
D)  it decreases 25% 
E)  it decreases 17%

Question 20

When a current flows down a wire

Accepted Answer

A)  electrons are moving in the direction of the current. 
B)  electrons are moving opposite the direction of the current. 
C)  protons are moving in the direction of the current. 
D)  protons are moving opposite the direction of the current. 
E)  both protons and electrons are moving in the direction of the current. 
A)  electrons are moving in the direction of the current. 
B)  electrons are moving opposite the direction of the current. 
C)  protons are moving in the direction of the current. 
D)  protons are moving opposite the direction of the current. 
E)  both protons and electrons are moving in the direction of the current.

Exam 18: Electric Current and Circuits

Of the common battery sizes AAA,AA,C,and D,which provides the highest emf?

In the diagram,if the current through R1 is 5 A up and if the current through R3 is 3 A up, what is the current in R2?

Copper has 8.5 ×\times× 1028 current carrying electrons per m3. A copper wire of radius 0.15 mm carries a current of 17 mA.What is the average drift velocity for the electrons?

A capacitor in an RC circuit is charged,storing energy 1.25 mJ.What is the time required to discharge this capacitor,as compared to the time required to discharge an identical capacitor in an identical RC circuit which has stored 2.5 mJ?

A series circuit consists of a 12.0 V source of emf, a 2.00 mF capacitor,a 1000 Ω\OmegaΩ resistor, and a switch.What is the time constant for this circuit?

In a series circuit consisting of a 12.0 emf,a 2.00 mF capacitor,a 1.00 k Ω\OmegaΩ resistor and a switch,what is the voltage across the capacitor at a time τ\tauτ after the switch is closed?

An electron beam contains 1.5 ×\times× 1017 electrons per m3 and is confined to circular region of diameter 0.025 mm.The electrons in the beam are extremely energetic,and travel at nearly the speed of light.What is the current in the beam?

One hundred meters of 2.00 mm diameter wire has a resistance of 0.532 Ω\OmegaΩ .What is the resistivity of the material from which the wire is made?

Four 12 Ω\OmegaΩ resistors are connected together.Which of the following resistances cannot be formed using all 4 resistors?

A series circuit consists of a 12.0 V source of emf,a 2.00 mF capacitor,a 1000 Ω\OmegaΩ resistor,and a switch.When the switch is closed,how long does it take for the current to reach one-tenth its maximum value?

In an RC circuit with an initially uncharged capacitor,the time constant is the time that is required for the charge on the capacitor to reach what percentage of its final value?

A flashlight,which uses two 1.5 V batteries in series,is turned on for 2.0 minutes.If the current in the flashlight is 100 mA,what is the energy dissipated?

If R1 = 6.0 Ω\OmegaΩ , R2 = 8.0 Ω\OmegaΩ , R3 = 2.0 Ω\OmegaΩ , ε\varepsilonε 1 = 4.0 V, and ε\varepsilonε 2 = 14 V,what is the power supplied to the circuit by ε\varepsilonε 1?

In the diagram,each resistor is 3 ohms and the battery is 9 volts.What is the current through the middle resistor?

A potential difference of 12.4 V is placed across a 4.1 Ω\OmegaΩ resistor.What is the current in the resistor?

A 1.56-V battery has an internal resistance of 0.120 Ω\OmegaΩ .What is the maximum current that can be drawn from this battery?

Four 12 Ω\OmegaΩ resistors are connected together.What is the least resistance that can be attained with these resistors?

A 1000 Ω\OmegaΩ resistor is in a circuit with 30.0 mA flowing through it.A voltmeter with internal resistance 1000 Ω\OmegaΩ is used to measure the voltage across the resistor.What is the reading from the voltmeter if 30.0 mA still flows in the circuit?

A variable resistor has a voltage of 12.0 V placed across it.If the resistance is increased 20%,what happens to the current through it?

When a current flows down a wire

Introduction

Force

Acceleration and Newtons Second Law of Motion

Motion With Constant Acceleration

Circular Motion

Conservation of Energy

Linear Momentum

Torque and Angular Momentum

Fluids

Elasticity and Oscillations

Waves

Sound

Temperature and the Ideal Gas

Heat

Thermodynamics

Electric Forces and Fields

Electric Potential

Magnetic Forces and Fields

Electromagnetic Induction

Alternating Current

Electromagnetic Waves

Reflection and Refraction of Light

Optical Instruments

Interference and Diffraction

Relativity

Early Quantum Physics and the Photon

Quantum Physics

Nuclear Physics

Particle Physics

Filters

In the diagram,if the current through R₁ is 5 A up and if the current through R₃ is 3 A up, what is the current in R₂?

Copper has 8.5 $\times$ 10²⁸ current carrying electrons per m³. A copper wire of radius 0.15 mm carries a current of 17 mA.What is the average drift velocity for the electrons?

A series circuit consists of a 12.0 V source of emf, a 2.00 mF capacitor,a 1000 $\Omega$ resistor, and a switch.What is the time constant for this circuit?

In a series circuit consisting of a 12.0 emf,a 2.00 mF capacitor,a 1.00 k $\Omega$ resistor and a switch,what is the voltage across the capacitor at a time $\tau$ after the switch is closed?

An electron beam contains 1.5 $\times$ 10¹⁷ electrons per m³ and is confined to circular region of diameter 0.025 mm.The electrons in the beam are extremely energetic,and travel at nearly the speed of light.What is the current in the beam?

One hundred meters of 2.00 mm diameter wire has a resistance of 0.532 $\Omega$ .What is the resistivity of the material from which the wire is made?

Four 12 $\Omega$ resistors are connected together.Which of the following resistances cannot be formed using all 4 resistors?

A series circuit consists of a 12.0 V source of emf,a 2.00 mF capacitor,a 1000 $\Omega$ resistor,and a switch.When the switch is closed,how long does it take for the current to reach one-tenth its maximum value?

A potential difference of 12.4 V is placed across a 4.1 $\Omega$ resistor.What is the current in the resistor?

A 1.56-V battery has an internal resistance of 0.120 $\Omega$ .What is the maximum current that can be drawn from this battery?

Four 12 $\Omega$ resistors are connected together.What is the least resistance that can be attained with these resistors?

A 1000 $\Omega$ resistor is in a circuit with 30.0 mA flowing through it.A voltmeter with internal resistance 1000 $\Omega$ is used to measure the voltage across the resistor.What is the reading from the voltmeter if 30.0 mA still flows in the circuit?