Question 1

The potential difference between two ends of a 45-cm length of copper wire (1.7 $\times$
 10-8  $\Omega$·m) is 1.5 V. The magnitude of the current density in the wire is

Accepted Answer

A)  1.0 $\times$
 108 A/m2. 
B)  1.5 $\times$
 108 A/m2. 
C)  2.0 $\times$
 108 A/m2. 
D)  2.5 $\times$
 108 A/m2. 
A)  1.0 $\times$
 108 A/m2. 
B)  1.5 $\times$
 108 A/m2. 
C)  2.0 $\times$
 108 A/m2. 
D)  2.5 $\times$
 108 A/m2.

Question 2

Two resistors, 20  $\Omega$ and 30  $\Omega$, are connected in parallel. A third resistor, 24  $\Omega$, is connected in series with the parallel combination. The equivalent resistance of the networks is

Accepted Answer

A)  16  $\Omega$ 
B)  36  $\Omega$. 
C)  50 $\Omega$. 
D)  74 $\Omega$. 
A)  16  $\Omega$ 
B)  36  $\Omega$. 
C)  50 $\Omega$. 
D)  74 $\Omega$.

Question 3

The current in a wire is measured at 1.0 A when the wire is at 20.0°C. As the wire heats up to 80°C, the current drops to 0.77 A while the voltage remains constant. The temperature coefficient of resistance of the material is

Accepted Answer

A)  0.8 $\times$
 10-3 /°C. 
B)  1.0 $\times$
 10-3 /°C. 
C)  5.0 $\times$
 10-3 /°C. 
D)  8.0 $\times$
 10-3 /°C. 
A)  0.8 $\times$
 10-3 /°C. 
B)  1.0 $\times$
 10-3 /°C. 
C)  5.0 $\times$
 10-3 /°C. 
D)  8.0 $\times$
 10-3 /°C.

Question 4

In metric units, the dimensions of current are

Accepted Answer

A)  coulombs. 
B)  coulombs·second. 
C)  coulombs/second. 
D)  coulombs·second2. 
A)  coulombs. 
B)  coulombs·second. 
C)  coulombs/second. 
D)  coulombs·second2.

Question 5

Two resistors, 20 $\Omega$ and 30  $\Omega$, are connected in parallel. A third resistor, 24  $\Omega$, is connected in series with the parallel combination. A 36-V power source is connected to the series-parallel combination. The voltage drop across the 20- $\Omega$ resistor is

Accepted Answer

A)  36 V. 
B)  24 V. 
C)  12 V. 
D)  zero. 
A)  36 V. 
B)  24 V. 
C)  12 V. 
D)  zero.

Question 6

When a 1.5-V potential is applied across a parallel network of two identical resistors, the net current is 1.0 A. The individual resistance of each resistor is

Accepted Answer

A)  1.5  $\Omega$. 
B)  3.0  $\Omega$. 
C)  15 $\Omega$. 
D)  0.67 $\Omega$ 
A)  1.5  $\Omega$. 
B)  3.0  $\Omega$. 
C)  15 $\Omega$. 
D)  0.67 $\Omega$

Question 7

A resistor of 1000  $\Omega$ has 150 mA flowing through it. The voltage across the resistor is

Accepted Answer

A)  150 V. 
B)  67 V. 
C)  15 V. 
D)  6.7 V. 
A)  150 V. 
B)  67 V. 
C)  15 V. 
D)  6.7 V.

Question 8

Five incandescent lightbulbs are connected in parallel. One of the bulbs burns out, causing the current through the other bulbs to

Accepted Answer

A)  increase. 
B)  decrease. 
C)  remain the same. 
D)  drop to zero. 
A)  increase. 
B)  decrease. 
C)  remain the same. 
D)  drop to zero.

Question 9

A total of 3.0 $\times$ 1015 electrons pass through a wire in 48.0 ms. The current is

Accepted Answer

A)  10 $\mu$ A. 
B)  0.10 mA. 
C)  15 mA. 
D)  100 pA. 
A)  10 $\mu$ A. 
B)  0.10 mA. 
C)  15 mA. 
D)  100 pA.

Question 10

Two resistors, 20 $\Omega$ and 30  $\Omega$, are connected in parallel. A third resistor, 24  $\Omega$, is connected in series with the parallel combination. A 36-V power source is connected to the series-parallel combination. The current through the 24- $\Omega$ resistor is

Accepted Answer

A)  0.50 A. 
B)  1.0 A. 
C)  1.5 A. 
D)  2.0 A. 
A)  0.50 A. 
B)  1.0 A. 
C)  1.5 A. 
D)  2.0 A.

Question 11

The potential difference between two ends of a 45-cm length of wire is 1.5 V. The magnitude of the electric field in the wire is

Accepted Answer

A)  3.3mV/m. 
B)  3.3 V/m. 
C)  0.67 V/m. 
D)  6.7 V/m. 
A)  3.3mV/m. 
B)  3.3 V/m. 
C)  0.67 V/m. 
D)  6.7 V/m.

Question 12

A copper slab has dimensions of 20 cm x 30 cm x 60 cm. The two opposite sides of the slab that would have the largest resistance are given by the dimensions

Accepted Answer

A)  20 cm *30 cm. 
B)  20 cm*60 cm. 
C)  30 cm * 60 cm. 
D)  Hold on; all the resistances are the same. 
A)  20 cm *30 cm. 
B)  20 cm*60 cm. 
C)  30 cm * 60 cm. 
D)  Hold on; all the resistances are the same.

Question 13

A current of 1.5 is produced through a conductor whose resistance is 0.50  $\Omega$. The potential necessary to produce this current is

Accepted Answer

A)  3.0 V. 
B)  0.75 V. 
C)  0.33 V. 
D)  1.1 V. 
A)  3.0 V. 
B)  0.75 V. 
C)  0.33 V. 
D)  1.1 V.

Question 14

The direction of the conventional current flow is best described as

Accepted Answer

A)  the direction of a hypothetical positive charge in the circuit. 
B)  the actual direction of the negatively charged electrons in the circuit. 
C)  the path the electrons follow from the positive to the negative terminals of the battery. 
D)  the path of ions from the positive to the negative terminals of the battery. 
A)  the direction of a hypothetical positive charge in the circuit. 
B)  the actual direction of the negatively charged electrons in the circuit. 
C)  the path the electrons follow from the positive to the negative terminals of the battery. 
D)  the path of ions from the positive to the negative terminals of the battery.

Question 15

Four 24- $\Omega$ resistors are connected in a square configuration. The resistance as measured across any one of the resistors is

Accepted Answer

A)  12  $\Omega$ 
B)  18  $\Omega$. 
C)  24  $\Omega$. 
D)  96  $\Omega$. 
A)  12  $\Omega$ 
B)  18  $\Omega$. 
C)  24  $\Omega$. 
D)  96  $\Omega$.

Question 16

Consider the resistance of two wires made of the same material. Wire A has a length that is twice the length of wire B; the cross-sectional area of wire A is twice the cross-sectional area of wire B. The resistance of wire A is

Accepted Answer

A)  the same as wire B. 
B)  twice the value of wire B. 
C)  half the value of wire B. 
D)  one-quarter the value of wire B. 
A)  the same as wire B. 
B)  twice the value of wire B. 
C)  half the value of wire B. 
D)  one-quarter the value of wire B.

Question 17

Two resistors are connected in series, and the value of R1 is twice the value of R2. The resistor with the larger current through it is

Accepted Answer

A)  R1. 
B)  R2. 
C)  Both resistors have the same current through them. 
D)  None of the above answers is correct. 
A)  R1. 
B)  R2. 
C)  Both resistors have the same current through them. 
D)  None of the above answers is correct.

Question 18

Two resistors, 20  $\Omega$ and 30  $\Omega$, are connected in parallel. A third resistor, 24  $\Omega$, is connected in series with the parallel combination. A 36-V power source is connected to the series-parallel combination. The current through the 20- $\Omega$ resistor is

Accepted Answer

A)  0.40 A. 
B)  0.60 A. 
C)  1.0 A. 
D)  zero. 
A)  0.40 A. 
B)  0.60 A. 
C)  1.0 A. 
D)  zero.

Question 19

A wire's diameter decreases linearly from di to df = di/2. If the electron drift velocity at the other end of the wire is vi, then the drift velocity at the end whose diameter is di/2

Accepted Answer

A)  decreases by a factor of 2. 
B)  increases by a factor of 2. 
C)  increases by a factor of 4. 
D)  remains the same. 
A)  decreases by a factor of 2. 
B)  increases by a factor of 2. 
C)  increases by a factor of 4. 
D)  remains the same.

Question 20

In metric units the dimensions of current density are consistent with

Accepted Answer

A)  ampere. 
B)  ampere·meter. 
C)  ampere/meter2. 
D)  ampere/meter3. 
A)  ampere. 
B)  ampere·meter. 
C)  ampere/meter2. 
D)  ampere/meter3.

Exam 27: Currents and Ohms Law

The potential difference between two ends of a 45-cm length of copper wire (1.7 ×\times× 10-8 Ω\OmegaΩ ·m) is 1.5 V. The magnitude of the current density in the wire is

Two resistors, 20 Ω\OmegaΩ and 30 Ω\OmegaΩ , are connected in parallel. A third resistor, 24 Ω\OmegaΩ , is connected in series with the parallel combination. The equivalent resistance of the networks is

The current in a wire is measured at 1.0 A when the wire is at 20.0°C. As the wire heats up to 80°C, the current drops to 0.77 A while the voltage remains constant. The temperature coefficient of resistance of the material is

In metric units, the dimensions of current are

Two resistors, 20 Ω\OmegaΩ and 30 Ω\OmegaΩ , are connected in parallel. A third resistor, 24 Ω\OmegaΩ , is connected in series with the parallel combination. A 36-V power source is connected to the series-parallel combination. The voltage drop across the 20- Ω\OmegaΩ resistor is

When a 1.5-V potential is applied across a parallel network of two identical resistors, the net current is 1.0 A. The individual resistance of each resistor is

A resistor of 1000 Ω\OmegaΩ has 150 mA flowing through it. The voltage across the resistor is

Five incandescent lightbulbs are connected in parallel. One of the bulbs burns out, causing the current through the other bulbs to

A total of 3.0 ×\times× 1015 electrons pass through a wire in 48.0 ms. The current is

Two resistors, 20 Ω\OmegaΩ and 30 Ω\OmegaΩ , are connected in parallel. A third resistor, 24 Ω\OmegaΩ , is connected in series with the parallel combination. A 36-V power source is connected to the series-parallel combination. The current through the 24- Ω\OmegaΩ resistor is

The potential difference between two ends of a 45-cm length of wire is 1.5 V. The magnitude of the electric field in the wire is

A copper slab has dimensions of 20 cm x 30 cm x 60 cm. The two opposite sides of the slab that would have the largest resistance are given by the dimensions

A current of 1.5 is produced through a conductor whose resistance is 0.50 Ω\OmegaΩ . The potential necessary to produce this current is

The direction of the conventional current flow is best described as

Four 24- Ω\OmegaΩ resistors are connected in a square configuration. The resistance as measured across any one of the resistors is

Consider the resistance of two wires made of the same material. Wire A has a length that is twice the length of wire B; the cross-sectional area of wire A is twice the cross-sectional area of wire B. The resistance of wire A is

Two resistors are connected in series, and the value of R1 is twice the value of R2. The resistor with the larger current through it is

Two resistors, 20 Ω\OmegaΩ and 30 Ω\OmegaΩ , are connected in parallel. A third resistor, 24 Ω\OmegaΩ , is connected in series with the parallel combination. A 36-V power source is connected to the series-parallel combination. The current through the 20- Ω\OmegaΩ resistor is

A wire's diameter decreases linearly from di to df = di/2. If the electron drift velocity at the other end of the wire is vi, then the drift velocity at the end whose diameter is di/2

In metric units the dimensions of current density are consistent with

Space, Time, and Mass

Motion Along a Straight Line

Vectors

Motion in Two and Three Dimensions

Newtons Laws of Motion

Further Applications of Newtons Laws

Work and Energy

Conservation of Energy

Gravitation

Systems of Particles

Collisions

Rotation of a Rigid Body

Dynamics of a Rigid Body

Statics and Elasticity

Oscillations

Waves

Sound

Fluid Mechanics

The Ideal Gas

Heat

Thermodynamics

Electric Force and the Electric Charge

The Electric Field

Gauss Law

Electrostatic Potential and Energy

Capacitors and Dielectrics

Direct Current Circuits

Magnetic Force and Field

Charges and Currents in Magnetic Fields

Electromagnetic Induction

Alternating Current Circuits

Electromagnetic Waves

Reflection, Refraction, and Optics

Interference and Diffraction

The Theory of Special Relativity

Quanta of Light

Spectral Lines, Bohrs Theory, and Quantum Mechanics

Quantum Structure of Atoms, Molecules, and Solids

Nuclei

Elementary Particles and Cosmology

Filters

The potential difference between two ends of a 45-cm length of copper wire (1.7 $\times$ 10^-8 $\Omega$ ·m) is 1.5 V. The magnitude of the current density in the wire is

Two resistors, 20 $\Omega$ and 30 $\Omega$ , are connected in parallel. A third resistor, 24 $\Omega$ , is connected in series with the parallel combination. The equivalent resistance of the networks is

Two resistors, 20 $\Omega$ and 30 $\Omega$ , are connected in parallel. A third resistor, 24 $\Omega$ , is connected in series with the parallel combination. A 36-V power source is connected to the series-parallel combination. The voltage drop across the 20- $\Omega$ resistor is

A resistor of 1000 $\Omega$ has 150 mA flowing through it. The voltage across the resistor is

A total of 3.0 $\times$ 10¹⁵ electrons pass through a wire in 48.0 ms. The current is

Two resistors, 20 $\Omega$ and 30 $\Omega$ , are connected in parallel. A third resistor, 24 $\Omega$ , is connected in series with the parallel combination. A 36-V power source is connected to the series-parallel combination. The current through the 24- $\Omega$ resistor is

A current of 1.5 is produced through a conductor whose resistance is 0.50 $\Omega$ . The potential necessary to produce this current is

Four 24- $\Omega$ resistors are connected in a square configuration. The resistance as measured across any one of the resistors is

Two resistors are connected in series, and the value of R₁ is twice the value of R₂. The resistor with the larger current through it is

Two resistors, 20 $\Omega$ and 30 $\Omega$ , are connected in parallel. A third resistor, 24 $\Omega$ , is connected in series with the parallel combination. A 36-V power source is connected to the series-parallel combination. The current through the 20- $\Omega$ resistor is

A wire's diameter decreases linearly from d_i to d_f = d_i/2. If the electron drift velocity at the other end of the wire is v_i, then the drift velocity at the end whose diameter is d_i/2