Question 1

An 800 V/m electric field is directed along the +x-axis. If the potential at x = 0 m is 2000 V, what is the potential at x = 2 m?

Accepted Answer

A) 200 V 
B) 400 V 
C) 600 V 
D) 800 V 
E) 1000 V 
A) 200 V 
B) 400 V 
C) 600 V 
D) 800 V 
E) 1000 V B

Question 2

Two uniformly distributed rings of charge, one of total charge Q1 and radius r1 and the other of total charge Q2 and radius r2, have the same center. The potential at the center is

Accepted Answer

Q₁/4π ε_O r₁ + Q₂/4π ε_O r₂.

Question 3

The component of the electric field in any direction is equal to the negative of the rate of change of the electric potential with distance in that direction.

Accepted Answer

A) True 
 B)False  True

Question 4

FIGURE 23-11  
-Fig. 23-11 shows the variation of the electric potential V (measured in Volts) as a function of the radial direction r (measured in meters). For which range of r is the magnitude of the electric field the largest?

Accepted Answer

A) from r = 2 m to r = 4 m 
B) from r = 4 m to r = 6 m 
C) from r = 0 to r = 2 m 
D) The magnitude of the field is the same everywhere. 
E) More information is needed to answer the question. 
A) from r = 2 m to r = 4 m 
B) from r = 4 m to r = 6 m 
C) from r = 0 to r = 2 m 
D) The magnitude of the field is the same everywhere. 
E) More information is needed to answer the question.

Question 5

A +8.00-μC charge is situated along the +y-axis at y = 0.400 m. What is the electric potential at the origin because of this charge?

Accepted Answer

A) +180 × 103 V 
B) -180 × 103 V 
C) 0 V 
D) -288 × 103 V 
E) +288 × 103 V 
A) +180 × 103 V 
B) -180 × 103 V 
C) 0 V 
D) -288 × 103 V 
E) +288 × 103 V

Question 6

Three electric charges QA = q, QB = -q, and QC = -2q are located at the points A (x = + a, y = 0), B (x = -a, y = 0), and C (x = 0, y = +2a) respectively. What is the value of the electric potential at the origin?

Accepted Answer

Question 7

If a particle with a charge of 2 coulombs moves through a potential difference of 12 volts, its change in kinetic energy will a have magnitude of

Accepted Answer

A) 12 J. 
B) 6 J. 
C) 8 J. 
D) 1/6 J. 
E) 24 J. 
A) 12 J. 
B) 6 J. 
C) 8 J. 
D) 1/6 J. 
E) 24 J.

Question 8

Two electric charges QA = + 1.0 μC and QB= - 2.0 μC are located 0.50 m apart. How much work is needed to move the charges apart and double the distance between them?

Accepted Answer

A) -36 × 10-3J 
B) +18 × 10-3 
C) 0 
D) +36 × 10-3 
E) -18 × 10-3 
A) -36 × 10-3J 
B) +18 × 10-3 
C) 0 
D) +36 × 10-3 
E) -18 × 10-3

Question 9

An electron is accelerated from rest through a potential difference of 1000 volts giving it a kinetic energy of

Accepted Answer

A) 1.6 × 10-22 eV. 
B) 0.001 eV. 
C) 1.6 × 10-16 J. 
D) 1.6 × 10-22 J. 
E) 1.6 × 10-16 eV. 
A) 1.6 × 10-22 eV. 
B) 0.001 eV. 
C) 1.6 × 10-16 J. 
D) 1.6 × 10-22 J. 
E) 1.6 × 10-16 eV.

Question 10

If the potential is given by 6/ x2, the x-component of the electric field is

Accepted Answer

A) -12 x-3. 
B) -6x. 
C) 12 x-3. 
D) 12x. 
E) 6x. 
A) -12 x-3. 
B) -6x. 
C) 12 x-3. 
D) 12x. 
E) 6x.

Question 11

A large plate carries a uniform charge density σ = 8.85 × 10-9 C/ m2. A pattern showing equipotential surfaces with a 5 V potential difference would appear as

Accepted Answer

A) a series of planes perpendicular to the plate, 1 cm apart. 
B) a series of lines perpendicular to the plate, 1 cm apart. 
C) a series of lines parallel to the plate, 1 cm apart. 
D) a series of circles of radius 1 cm, parallel to the plate. 
E) a series of planes parallel to the plate, 1 cm apart. 
A) a series of planes perpendicular to the plate, 1 cm apart. 
B) a series of lines perpendicular to the plate, 1 cm apart. 
C) a series of lines parallel to the plate, 1 cm apart. 
D) a series of circles of radius 1 cm, parallel to the plate. 
E) a series of planes parallel to the plate, 1 cm apart.

Question 12

Every point on an equipotential surface is at the same potential.

Accepted Answer

A) True 
 B)False

Question 13

At a certain point in space the electric potential is 20 V. A 4.0-μC charge is brought from infinity to that point. What is the electric potential energy of this charge at that point?

Accepted Answer

A) - 80 μJ 
B) 80 μJ 
C) - 20 μJ 
D) 20 μJ 
E) 4.0 μJ 
A) - 80 μJ 
B) 80 μJ 
C) - 20 μJ 
D) 20 μJ 
E) 4.0 μJ

Question 14

If an electron is accelerated through a potential difference of 500 V between two parallel plates separated by a distance of 2.0 cm. The change in kinetic energy of the electron during this motion is

Accepted Answer

A) 100 eV. 
B) 2000 eV. 
C) 250 eV. 
D) 500 eV. 
E) 1000 eV. 
A) 100 eV. 
B) 2000 eV. 
C) 250 eV. 
D) 500 eV. 
E) 1000 eV.

Question 15

If the electric field is zero in some region of space is the electric potential zero there as well? Explain.

Accepted Answer

Not necessarily. The electric field is r

Question 16

If an electron is accelerated from rest through a potential difference of 25,000 volts in a color television picture tube, its kinetic energy will be

Accepted Answer

A) 16 J. 
B) 2.5 × 104 J. 
C) 4.0 × 10-5J. 
D) 1.6 J. 
E) 4.0 × 10-15 J. 
A) 16 J. 
B) 2.5 × 104 J. 
C) 4.0 × 10-5J. 
D) 1.6 J. 
E) 4.0 × 10-15 J.

Question 17

A negative charge, if free, tries to move

Accepted Answer

A) from high potential to low potential. 
B) from low potential to high potential. 
C) toward infinity. 
D) away from infinity. 
E) in the direction of the electric field. 
A) from high potential to low potential. 
B) from low potential to high potential. 
C) toward infinity. 
D) away from infinity. 
E) in the direction of the electric field.

Question 18

Three negative charges of equal magnitudes are positioned along the x-axis at x = -a, x=0, and x = +a respectively. The charge located at x=0 is moved away along the y-axis to a position (x,y) = (0, +a). How does the potential energy of the system of charges change as a result?

Accepted Answer

A) The potential energy may increase or decrease depending on the magnitude of the charges. 
B) The potential energy increases. 
C) The potential energy decreases. 
D) The potential energy stays the same. 
E) More information is needed to answer the question. 
A) The potential energy may increase or decrease depending on the magnitude of the charges. 
B) The potential energy increases. 
C) The potential energy decreases. 
D) The potential energy stays the same. 
E) More information is needed to answer the question.

Question 19

If the electric field is 12 V/m in the positive x-direction, what is the potential difference between the origin, (0, 0), and the point (3.0 m, 4.0 m)?

Accepted Answer

A) 48 V with the origin at the higher potential 
B) 48 V with the origin at the lower potential 
C) 36 V with the origin at the lower potential 
D) 36 V with the origin at the higher potential 
E) cannot be determined 
A) 48 V with the origin at the higher potential 
B) 48 V with the origin at the lower potential 
C) 36 V with the origin at the lower potential 
D) 36 V with the origin at the higher potential 
E) cannot be determined

Question 20

All points on the perpendicular bisector of the line joining two equal but opposite charges have a potential of zero.

Accepted Answer

A) True 
 B)False

Exam 23: Electric Potential

An 800 V/m electric field is directed along the +x-axis. If the potential at x = 0 m is 2000 V, what is the potential at x = 2 m?

Two uniformly distributed rings of charge, one of total charge Q1 and radius r1 and the other of total charge Q2 and radius r2, have the same center. The potential at the center is

The component of the electric field in any direction is equal to the negative of the rate of change of the electric potential with distance in that direction.

FIGURE 23-11 -Fig. 23-11 shows the variation of the electric potential V (measured in Volts) as a function of the radial direction r (measured in meters). For which range of r is the magnitude of the electric field the largest?

A +8.00-μC charge is situated along the +y-axis at y = 0.400 m. What is the electric potential at the origin because of this charge?

Three electric charges QA = q, QB = -q, and QC = -2q are located at the points A (x = + a, y = 0), B (x = -a, y = 0), and C (x = 0, y = +2a) respectively. What is the value of the electric potential at the origin?

If a particle with a charge of 2 coulombs moves through a potential difference of 12 volts, its change in kinetic energy will a have magnitude of

Two electric charges QA = + 1.0 μC and QB= - 2.0 μC are located 0.50 m apart. How much work is needed to move the charges apart and double the distance between them?

An electron is accelerated from rest through a potential difference of 1000 volts giving it a kinetic energy of

If the potential is given by 6/ x2, the x-component of the electric field is

A large plate carries a uniform charge density σ = 8.85 × 10-9 C/ m2. A pattern showing equipotential surfaces with a 5 V potential difference would appear as

Every point on an equipotential surface is at the same potential.

At a certain point in space the electric potential is 20 V. A 4.0-μC charge is brought from infinity to that point. What is the electric potential energy of this charge at that point?

If an electron is accelerated through a potential difference of 500 V between two parallel plates separated by a distance of 2.0 cm. The change in kinetic energy of the electron during this motion is

If the electric field is zero in some region of space is the electric potential zero there as well? Explain.

If an electron is accelerated from rest through a potential difference of 25,000 volts in a color television picture tube, its kinetic energy will be

A negative charge, if free, tries to move

Three negative charges of equal magnitudes are positioned along the x-axis at x = -a, x=0, and x = +a respectively. The charge located at x=0 is moved away along the y-axis to a position (x,y) = (0, +a). How does the potential energy of the system of charges change as a result?

If the electric field is 12 V/m in the positive x-direction, what is the potential difference between the origin, (0, 0), and the point (3.0 m, 4.0 m)?

All points on the perpendicular bisector of the line joining two equal but opposite charges have a potential of zero.

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Two uniformly distributed rings of charge, one of total charge Q₁ and radius r₁ and the other of total charge Q₂ and radius r₂, have the same center. The potential at the center is

Three electric charges Q_A = q, Q_B = -q, and Q_C = -2q are located at the points A (x = + a, y = 0), B (x = -a, y = 0), and C (x = 0, y = +2a) respectively. What is the value of the electric potential at the origin?

Two electric charges Q_A = + 1.0 μC and Q_B= - 2.0 μC are located 0.50 m apart. How much work is needed to move the charges apart and double the distance between them?

If the potential is given by 6/ x², the x-component of the electric field is

A large plate carries a uniform charge density σ = 8.85 × 10^-9 C/ m². A pattern showing equipotential surfaces with a 5 V potential difference would appear as