Question 1

A capacitor, in addition to storing charge, also stores electrical energy.

Accepted Answer

A) True 
 B)False

Question 2

A 4.0-μC charge is situated at the origin of an xy-coordinate system. What is the potential difference between the points x = 4.0 m and y = 2.0 m because of this charge?

Accepted Answer

A)  -9.0 × 103 V 
B)  9.0 × 103 V 
C)  -36 × 103 V 
D)  36 × 103 V 
E)  0 V 
A)  -9.0 × 103 V 
B)  9.0 × 103 V 
C)  -36 × 103 V 
D)  36 × 103 V 
E)  0 V

Question 3

The electric potential at the origin of an xy-coordinate system is 40 V. A -8.0-μC charge is brought from x = +∞ to that point. What is the electric potential energy of this charge at the origin?

Accepted Answer

A)  -3.2 × 10-4 J 
B)  3.2 × 10-4 J 
C)  -40 μJ 
D)  40 μJ 
E)  8.0 μJ 
A)  -3.2 × 10-4 J 
B)  3.2 × 10-4 J 
C)  -40 μJ 
D)  40 μJ 
E)  8.0 μJ

Question 4

An electron is carried from the positive terminal to the negative terminal of a 9 V battery. How much work is required in carrying this electron?

Accepted Answer

A)  1.6 × 10-19 J 
B)  17 × 10-19 J 
C)  9 J 
D)  14.4 × 10-19 J 
E)  14.4 × 10-19 J/C 
A)  1.6 × 10-19 J 
B)  17 × 10-19 J 
C)  9 J 
D)  14.4 × 10-19 J 
E)  14.4 × 10-19 J/C

Question 5

FIGURE 20-10  
-Two point charges of magnitude +4.00 μC and +2.00 μC are placed at the opposite corners of a rectangle as shown in Figure 20-10. What is the potential at point A due to these charges?

Accepted Answer

A)  +9.00 × 103 V 
B)  -9.00 × 103 V 
C)  -90.0 × 103 V 
D)  +90.0 × 103 V 
E)  +900 × 103 V 
A)  +9.00 × 103 V 
B)  -9.00 × 103 V 
C)  -90.0 × 103 V 
D)  +90.0 × 103 V 
E)  +900 × 103 V

Question 6

Three charges are placed as follows along the x- and y-axis of an xy-coordinate system: q1 = 2.00 μC at x1 = 0 m, q2 = -4.00 μC at x2 = 3.00 m, and q3 = 6.00 μC at y = 4.00 m. What is the electric potential energy of this system of charges?

Accepted Answer

A)  -40.2 mJ 
B)  40.2 mJ 
C)  -94.2 mJ 
D)  94.2 mJ 
E)  0 J 
A)  -40.2 mJ 
B)  40.2 mJ 
C)  -94.2 mJ 
D)  94.2 mJ 
E)  0 J

Question 7

Two point charges q1 = 4.0 μC and q2 = -8.0 μC are placed along the x-axis at x1 = 0 m and x2 = 0.20 m, respectively. What is the electric potential energy of this system of charges?

Accepted Answer

A)  +1.4 J 
B)  -1.4 J 
C)  -32 J 
D)  4.0 J 
E)  -4.0 J 
A)  +1.4 J 
B)  -1.4 J 
C)  -32 J 
D)  4.0 J 
E)  -4.0 J

Question 8

Three charges are placed as follows along the x- and y-axes of an xy-coordinate system: q1 = 2.00 μC at x1 = 0 m, q2 = 4.00 μC at x2 = 3.00 m, and q3 = 6.00 μC at y = 4.00 m. What is the electric potential energy of this system of charges?

Accepted Answer

A)  -94.2 mJ 
B)  94.2 mJ 
C)  0 J 
D)  -90.0 mJ 
E)  90.0 mJ 
A)  -94.2 mJ 
B)  94.2 mJ 
C)  0 J 
D)  -90.0 mJ 
E)  90.0 mJ

Question 9

An electron is initially at rest. It is accelerated through a potential difference of 400 V. What is the kinetic energy of this electron?

Accepted Answer

A)  6.4 × 10-17 J 
B)  400 J 
C)  0 J 
D)  800 J 
E)  6400 J 
A)  6.4 × 10-17 J 
B)  400 J 
C)  0 J 
D)  800 J 
E)  6400 J

Question 10

Two point charges of magnitude 4.0 μC and -4.0 μC are situated along the x-axis at x1 = 2.0 m and x2 = -2.0 m, respectively. What is the electric potential at the origin of the xy-coordinate system?

Accepted Answer

A)  -36 × 103 V 
B)  0 V 
C)  36 × 103 V 
D)  -48 × 103 V 
E)  48 × 103 V 
A)  -36 × 103 V 
B)  0 V 
C)  36 × 103 V 
D)  -48 × 103 V 
E)  48 × 103 V

Question 11

A capacitor consists of a set of two parallel plates of area A separated by a distance d. This capacitor is connected to a battery that maintains a constant potential difference between the plates. A slab of a dielectric material is inserted in the region between the plates so as to completely fill it. What changes would you observe?

Accepted Answer

A)  Only the charge in the capacitor would change. 
B)  Only the capacitance would change. 
C)  Both the charge in the capacitor and its capacitance would change. 
D)  Nothing would change. 
A)  Only the charge in the capacitor would change. 
B)  Only the capacitance would change. 
C)  Both the charge in the capacitor and its capacitance would change. 
D)  Nothing would change.

Question 12

Unlike electric potential, the electric potential energy is a vector quantity.

Accepted Answer

A) True 
 B)False

Question 13

Two equal point charges of magnitude 4.0 μC are situated along the x-axis at x1 = -2.0 m and x2 = 2.0 m. What is the electric potential at the origin of the xy-coordinate system?

Accepted Answer

A)  0 V 
B)  -36 × 103 V 
C)  36 × 103 V 
D)  -48 × 103 V 
E)  48 × 103 V 
A)  0 V 
B)  -36 × 103 V 
C)  36 × 103 V 
D)  -48 × 103 V 
E)  48 × 103 V

Question 14

State three reasons for adding a dielectric material between the plates of a capacitor.

Accepted Answer

(1)Dielectrics do not break down (allowi

Question 15

A potential changes at the greatest rate in the direction of the gradient of the potential.

Accepted Answer

A) True 
 B)False

Question 16

A surface on which all points are at the same potential is referred to as

Accepted Answer

A)  a constant electric force surface. 
B)  a constant electric field surface. 
C)  an equipotential surface. 
D)  an equivoltage surface. 
E)  a dielectric surface. 
A)  a constant electric force surface. 
B)  a constant electric field surface. 
C)  an equipotential surface. 
D)  an equivoltage surface. 
E)  a dielectric surface.

Question 17

A capacitor consists of a set of two parallel plates of area A separated by a distance d. This capacitor is connected to a battery and charged until its plates carry charges +Q and -Q. If the separation between the plates is doubled, the electrical energy stored in the capacitor will

Accepted Answer

A)  double. 
B)  quadruple. 
C)  be cut in half. 
D)  be cut in fourth. 
E)  not change. 
A)  double. 
B)  quadruple. 
C)  be cut in half. 
D)  be cut in fourth. 
E)  not change.

Question 18

The potential difference between the plates of a parallel plate capacitor is 35 V and the electric field between the plates has a strength of 750 V/m. If the plate area is 4.0 × 10-2 m2, what is the capacitance of this capacitor?

Accepted Answer

A)  7.6 × 10-14 F 
B)  7.6 × 10-12 F 
C)  7.6 × 10-11 F 
D)  7.6 × 10-10 F 
E)  None of the other choices is correct. 
A)  7.6 × 10-14 F 
B)  7.6 × 10-12 F 
C)  7.6 × 10-11 F 
D)  7.6 × 10-10 F 
E)  None of the other choices is correct.

Question 19

FIGURE 20-13  
-The equipotential surfaces between the two point charges are shown in Figure 20-13 with the value of potential marked for each line. If the distance between points A and B is 2.5 cm what is the intensity of the electric field between these two points?

Accepted Answer

A)  2 V/m 
B)  4 V/m 
C)  6 V/m 
D)  8 V/m 
E)  10 V/m 
A)  2 V/m 
B)  4 V/m 
C)  6 V/m 
D)  8 V/m 
E)  10 V/m

Question 20

When an electron moves in a direction opposite to the electric field, its potential increases but the potential energy decreases.

Accepted Answer

A) True 
 B)False

Exam 20: Electric Potential and Electric Potential Energy

A capacitor, in addition to storing charge, also stores electrical energy.

A 4.0-μC charge is situated at the origin of an xy-coordinate system. What is the potential difference between the points x = 4.0 m and y = 2.0 m because of this charge?

The electric potential at the origin of an xy-coordinate system is 40 V. A -8.0-μC charge is brought from x = +∞ to that point. What is the electric potential energy of this charge at the origin?

An electron is carried from the positive terminal to the negative terminal of a 9 V battery. How much work is required in carrying this electron?

FIGURE 20-10 -Two point charges of magnitude +4.00 μC and +2.00 μC are placed at the opposite corners of a rectangle as shown in Figure 20-10. What is the potential at point A due to these charges?

Three charges are placed as follows along the x- and y-axis of an xy-coordinate system: q1 = 2.00 μC at x1 = 0 m, q2 = -4.00 μC at x2 = 3.00 m, and q3 = 6.00 μC at y = 4.00 m. What is the electric potential energy of this system of charges?

Two point charges q1 = 4.0 μC and q2 = -8.0 μC are placed along the x-axis at x1 = 0 m and x2 = 0.20 m, respectively. What is the electric potential energy of this system of charges?

Three charges are placed as follows along the x- and y-axes of an xy-coordinate system: q1 = 2.00 μC at x1 = 0 m, q2 = 4.00 μC at x2 = 3.00 m, and q3 = 6.00 μC at y = 4.00 m. What is the electric potential energy of this system of charges?

An electron is initially at rest. It is accelerated through a potential difference of 400 V. What is the kinetic energy of this electron?

Two point charges of magnitude 4.0 μC and -4.0 μC are situated along the x-axis at x1 = 2.0 m and x2 = -2.0 m, respectively. What is the electric potential at the origin of the xy-coordinate system?

Unlike electric potential, the electric potential energy is a vector quantity.

Two equal point charges of magnitude 4.0 μC are situated along the x-axis at x1 = -2.0 m and x2 = 2.0 m. What is the electric potential at the origin of the xy-coordinate system?

State three reasons for adding a dielectric material between the plates of a capacitor.

A potential changes at the greatest rate in the direction of the gradient of the potential.

A surface on which all points are at the same potential is referred to as

A capacitor consists of a set of two parallel plates of area A separated by a distance d. This capacitor is connected to a battery and charged until its plates carry charges +Q and -Q. If the separation between the plates is doubled, the electrical energy stored in the capacitor will

The potential difference between the plates of a parallel plate capacitor is 35 V and the electric field between the plates has a strength of 750 V/m. If the plate area is 4.0 × 10-2 m2, what is the capacitance of this capacitor?

FIGURE 20-13 -The equipotential surfaces between the two point charges are shown in Figure 20-13 with the value of potential marked for each line. If the distance between points A and B is 2.5 cm what is the intensity of the electric field between these two points?

When an electron moves in a direction opposite to the electric field, its potential increases but the potential energy decreases.

Introduction to Physics

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Vectors in Physics

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Newtons Laws of Motion

Applications of Newtons Laws

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Linear Momentum and Collisions

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Electric Charges, Forces, and Fields

Electric Current and Direct-Current Circuits

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Magnetic Flux and Faradays Law of Induction

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Three charges are placed as follows along the x- and y-axis of an xy-coordinate system: q₁ = 2.00 μC at x₁ = 0 m, q₂ = -4.00 μC at x₂ = 3.00 m, and q₃ = 6.00 μC at y = 4.00 m. What is the electric potential energy of this system of charges?

Two point charges q₁ = 4.0 μC and q₂ = -8.0 μC are placed along the x-axis at x₁ = 0 m and x₂ = 0.20 m, respectively. What is the electric potential energy of this system of charges?

Three charges are placed as follows along the x- and y-axes of an xy-coordinate system: q₁ = 2.00 μC at x₁ = 0 m, q₂ = 4.00 μC at x₂ = 3.00 m, and q₃ = 6.00 μC at y = 4.00 m. What is the electric potential energy of this system of charges?

Two point charges of magnitude 4.0 μC and -4.0 μC are situated along the x-axis at x₁ = 2.0 m and x₂ = -2.0 m, respectively. What is the electric potential at the origin of the xy-coordinate system?

Two equal point charges of magnitude 4.0 μC are situated along the x-axis at x₁ = -2.0 m and x₂ = 2.0 m. What is the electric potential at the origin of the xy-coordinate system?

The potential difference between the plates of a parallel plate capacitor is 35 V and the electric field between the plates has a strength of 750 V/m. If the plate area is 4.0 × 10^-2 m², what is the capacitance of this capacitor?