Question 1

Coulomb's law: One very small uniformly charged plastic ball is located directly above another such charge in a test tube as shown in the figure. The balls are in equilibrium a distance d apart. If the charge on each ball is doubled, the distance between the balls in the test tube would become

Accepted Answer

According to Coulomb's law, the force between two charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. Therefore, if the charge on each ball is doubled, the force between them will be quadrupled (2*2=4). In order to restore equilibrium, the distance between the balls must also be doubled, since doubling the distance would result in a force that is one-fourth as strong (1/2)^2=1/4). Therefore, the distance between the balls would become 2d, as given in choice B.

Question 2

Coulomb's law: A 1.0-C point charge is 15 m from a second point charge, and the electric force on one of them due to the other is 1.0 N. What is the magnitude of the second charge? (k = 1/4πε₀ = 8.99 × 10⁹ N ∙ m²/C²)

Accepted Answer

E

Question 3

Electric field of multiple point-charges: The figure shows three electric charges labeled Q₁, Q₂, Q₃, and some electric field lines in the region surrounding the charges. What are the signs of the three charges?

Accepted Answer

Looking at the direction of the electric field lines, we can see that they are all pointing away from the charge labeled Q₂, indicating that it is negative. The field lines between the other two charges are a bit more difficult to interpret, but we can see that they curve in a way that suggests that the charges are opposite in sign, with the positive charge (Q₁) attracting field lines and the negative charge (Q₃) repelling them. Therefore, the signs of the charges are: Q₁ is positive, Q₂ is negative, and Q₃ is positive. Choice A is the correct answer.

Question 4

Charge: A piece of plastic has a net charge of +2.00 μC. How many more protons than electrons does this piece of plastic have? (e = 1.60 × 10^-19C)

Accepted Answer

To find the number of excess protons, divide the net charge by the charge of a single proton: (2.00 × 10^-6 C) / (1.60 × 10^-19 C/proton) = 1.25 × 10^13 protons.

Question 5

Motion of a charged particle: An electron is initially moving to the right when it enters a uniform electric field directed upwards. Which trajectory shown below will the electron follow?

Accepted Answer

The answer of Motion of a charged particle: An electron...

Question 6

Parallel plates: Two large, flat, horizontally oriented plates are parallel to each other, a distance d apart. Half way between the two plates the electric field has magnitude E. If the separation of the plates is reduced to d/2 what is the magnitude of the electric field half way between the plates?

Accepted Answer

The electric field between parallel plates is uniform and does not depend on the distance between the plates. Therefore, even if the separation is reduced, the electric field magnitude remains E.

Question 7

Coulomb's law: Charge Q₁ = 6.0 nC is at (0.30 m, 0), charge Q₂ = -1.0 nC is at (0, 0.10 m), and charge Q₃ = 5.0 nC is at (0, 0). What are the magnitude and direction of the net electrostatic force on the 5.0-nC charge due to the other charges? (k = 1/4πε₀ = 8.99 × 10⁹ N ∙ m²/C²)

Accepted Answer

The answer of Coulomb's law: Charge Q₁ = 6.0 nC...

Question 8

Electric field of multiple point-charges: Three equal negative point charges are placed at three of the corners of a square of side d as shown in the figure. Which of the arrows represents the direction of the net electric field at the center of the square?

Accepted Answer

The answer of Electric field of multiple point-charges: Three equal...

Question 9

Induction: X and Y are two uncharged metal spheres on insulating stands, and are in contact with each other. A positively charged rod R is brought close to X as shown in Figure (a).  Sphere Y is now moved away from X, as in Figure (b).  What are the final charge states of X and Y?

Accepted Answer

The answer of Induction: X and Y are two uncharged...

Question 10

Electric field of multiple point-charges: The figure shows two unequal point charges, q and Q, of opposite sign. Charge Q has greater magnitude than charge q. In which of the regions X, Y, Z will there be a point at which the net electric field due to these two charges is zero?

Accepted Answer

The answer of Electric field of multiple point-charges: The figure...

Question 11

Coulomb's law: Three point charges are placed on the x-axis. A charge of +2.0 μC is placed at the origin, -2.0 μC to the right at x = 50 cm, and +4.0 μC at the 100 cm mark. What are the magnitude and direction of the electrostatic force that acts on the charge at the origin? (k = 1/4πε₀ = 8.99 × 10⁹ N ∙ m²/C²)

Accepted Answer

The answer of Coulomb's law: Three point charges are placed...

Question 12

Electric field of multiple point-charges: Four equal negative point charges are located at the corners of a square, their positions in the xy-plane being (1, 1), (-1, 1), (-1, -1), (1, -1). The electric field on the x-axis at (1, 0) points in the same direction as

Accepted Answer

The answer of Electric field of multiple point-charges: Four equal...

Question 13

Coulomb's law: A point charge Q is located a short distance from a point charge 3Q, and no other charges are present. If the electrical force on Q is F, what is the electrical force on 3Q?

Accepted Answer

According to Coulomb's law, the electrical force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. Since the distance between the two charges (Q and 3Q) is the same and there are no other charges present, the magnitude of the electrical force between them is the same. Therefore, the electrical force on 3Q is also F.

Question 14

Coulomb's law: When two point charges are a distance d part, the electric force that each one feels from the other has magnitude F. In order to make this force twice as strong, the distance would have to be changed to

Accepted Answer

The answer of Coulomb's law: When two point charges are...

Question 15

Parallel plates: Two very large parallel sheets a distance d apart have their centers directly opposite each other. The sheets carry equal but opposite uniform surface charge densities. A point charge that is placed near the middle of the sheets a distance d/2 from each of them feels an electrical force F due to the sheets. If this charge is now moved closer to one of the sheets so that it is a distance d/4 from that sheet, what force will feel?

Accepted Answer

The electric field between two oppositely charged parallel plates is uniform and does not depend on the distance from the plates. Therefore, the force on the point charge, given by F = qE (where q is the charge and E is the electric field strength), remains constant regardless of the position between the plates.

Question 16

Coulomb's law: Two identical small conducting spheres are separated by 0.60 m. The spheres carry different amounts of charge and each sphere experiences an attractive electric force of 10.8 N. The total charge on the two spheres is -24 μC. The two spheres are now connected by a slender conducting wire, which is then removed. The electric force on each sphere is closest to

Accepted Answer

When the spheres are connected by a wire, charges redistribute equally. The total charge is -24 μC, so each sphere gets -12 μC. Using Coulomb's law, the force is repulsive because both spheres have the same charge, and the magnitude is calculated to be 3.6 N.

Question 17

Electric field of multiple point-charges: Two point charges Q₁ and Q₂ of equal magnitudes and opposite signs are positioned as shown in the figure. Which of the arrows best represents the net electric field at point P due to these two charges?

Accepted Answer

The answer of Electric field of multiple point-charges: Two point...

Question 18

Coulomb's law: When two point charges are 2.0 cm apart, each one experiences a 1.0-N electric force due to the other charge. If they are moved to a new separation of 8.0 cm, the electric force on each of them is closest to

Accepted Answer

Coulomb's law states that the electric force between two point charges is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them. When the distance is increased from 2.0 cm to 8.0 cm, the distance is quadrupled. Since the force varies inversely with the square of the distance, the new force is 1/16th of the original force. Therefore, if the original force was 1.0 N, the new force is 1.0 N / 16 = 0.0625 N, which is closest to 0.063 N.

Question 19

Coulomb's law: A positive point charge Q is fixed on a very large horizontal frictionless tabletop. A second positive point charge q is released from rest near the stationary charge and is free to move. Which statement best describes the motion of q after it is released?

Accepted Answer

The force between the charges decreases as q moves away from Q, but q will continue to accelerate away from Q, causing its speed to increase as it moves farther away.

Question 20

Coulomb's law: Two identical small charged spheres are a certain distance apart, and each one initially experiences an electrostatic force of magnitude F due to the other. With time, charge gradually leaks off of both spheres. When each of the spheres has lost half its initial charge, the magnitude of the electrostatic force will be

Accepted Answer

Coulomb's law states that electrostatic force is directly proportional to the product of charges and inversely proportional to the square of the distance between them. If both spheres lose half their charge, the force between them will become one-quarter of the original force because the product of charges is reduced by a factor of 4 (1/2 x 1/2) and the distance remains the same. Therefore, the correct answer is choice C, 1/4 F.

Quiz 17: Temperature and Heat

Coulomb's law: One very small uniformly charged plastic ball is located directly above another such charge in a test tube as shown in the figure. The balls are in equilibrium a distance d apart. If the charge on each ball is doubled, the distance between the balls in the test tube would become

Coulomb's law: A 1.0-C point charge is 15 m from a second point charge, and the electric force on one of them due to the other is 1.0 N. What is the magnitude of the second charge? (k = 1/4πε₀ = 8.99 × 10⁹ N ∙ m²/C²)

Electric field of multiple point-charges: The figure shows three electric charges labeled Q₁, Q₂, Q₃, and some electric field lines in the region surrounding the charges. What are the signs of the three charges?

Charge: A piece of plastic has a net charge of +2.00 μC. How many more protons than electrons does this piece of plastic have? (e = 1.60 × 10^-19C)

Motion of a charged particle: An electron is initially moving to the right when it enters a uniform electric field directed upwards. Which trajectory shown below will the electron follow?

Coulomb's law: Charge Q₁ = 6.0 nC is at (0.30 m, 0), charge Q₂ = -1.0 nC is at (0, 0.10 m), and charge Q₃ = 5.0 nC is at (0, 0). What are the magnitude and direction of the net electrostatic force on the 5.0-nC charge due to the other charges? (k = 1/4πε₀ = 8.99 × 10⁹ N ∙ m²/C²)

Electric field of multiple point-charges: Three equal negative point charges are placed at three of the corners of a square of side d as shown in the figure. Which of the arrows represents the direction of the net electric field at the center of the square?

Induction: X and Y are two uncharged metal spheres on insulating stands, and are in contact with each other. A positively charged rod R is brought close to X as shown in Figure (a) . Sphere Y is now moved away from X, as in Figure (b) . What are the final charge states of X and Y?

Electric field of multiple point-charges: The figure shows two unequal point charges, q and Q, of opposite sign. Charge Q has greater magnitude than charge q. In which of the regions X, Y, Z will there be a point at which the net electric field due to these two charges is zero?

Electric field of multiple point-charges: Four equal negative point charges are located at the corners of a square, their positions in the xy-plane being (1, 1) , (-1, 1) , (-1, -1) , (1, -1) . The electric field on the x-axis at (1, 0) points in the same direction as

Coulomb's law: A point charge Q is located a short distance from a point charge 3Q, and no other charges are present. If the electrical force on Q is F, what is the electrical force on 3Q?

Coulomb's law: When two point charges are a distance d part, the electric force that each one feels from the other has magnitude F. In order to make this force twice as strong, the distance would have to be changed to

Electric field of multiple point-charges: Two point charges Q₁ and Q₂ of equal magnitudes and opposite signs are positioned as shown in the figure. Which of the arrows best represents the net electric field at point P due to these two charges?

Coulomb's law: When two point charges are 2.0 cm apart, each one experiences a 1.0-N electric force due to the other charge. If they are moved to a new separation of 8.0 cm, the electric force on each of them is closest to

Coulomb's law: A positive point charge Q is fixed on a very large horizontal frictionless tabletop. A second positive point charge q is released from rest near the stationary charge and is free to move. Which statement best describes the motion of q after it is released?

Quiz 17: Temperature and Heat

Coulomb's law: One very small uniformly charged plastic ball is located directly above another such charge in a test tube as shown in the figure. The balls are in equilibrium a distance d apart. If the charge on each ball is doubled, the distance between the balls in the test tube would become

Coulomb's law: A 1.0-C point charge is 15 m from a second point charge, and the electric force on one of them due to the other is 1.0 N. What is the magnitude of the second charge? (k = 1/4πε0 = 8.99 × 109 N ∙ m2/C2)

Electric field of multiple point-charges: The figure shows three electric charges labeled Q1, Q2, Q3, and some electric field lines in the region surrounding the charges. What are the signs of the three charges?

Charge: A piece of plastic has a net charge of +2.00 μC. How many more protons than electrons does this piece of plastic have? (e = 1.60 × 10-19C)

Motion of a charged particle: An electron is initially moving to the right when it enters a uniform electric field directed upwards. Which trajectory shown below will the electron follow?

Coulomb's law: Charge Q1 = 6.0 nC is at (0.30 m, 0), charge Q2 = -1.0 nC is at (0, 0.10 m), and charge Q3 = 5.0 nC is at (0, 0). What are the magnitude and direction of the net electrostatic force on the 5.0-nC charge due to the other charges? (k = 1/4πε0 = 8.99 × 109 N ∙ m2/C2)

Electric field of multiple point-charges: Three equal negative point charges are placed at three of the corners of a square of side d as shown in the figure. Which of the arrows represents the direction of the net electric field at the center of the square?

Induction: X and Y are two uncharged metal spheres on insulating stands, and are in contact with each other. A positively charged rod R is brought close to X as shown in Figure (a) . Sphere Y is now moved away from X, as in Figure (b) . What are the final charge states of X and Y?

Electric field of multiple point-charges: The figure shows two unequal point charges, q and Q, of opposite sign. Charge Q has greater magnitude than charge q. In which of the regions X, Y, Z will there be a point at which the net electric field due to these two charges is zero?

Electric field of multiple point-charges: Four equal negative point charges are located at the corners of a square, their positions in the xy-plane being (1, 1) , (-1, 1) , (-1, -1) , (1, -1) . The electric field on the x-axis at (1, 0) points in the same direction as

Coulomb's law: A point charge Q is located a short distance from a point charge 3Q, and no other charges are present. If the electrical force on Q is F, what is the electrical force on 3Q?

Coulomb's law: When two point charges are a distance d part, the electric force that each one feels from the other has magnitude F. In order to make this force twice as strong, the distance would have to be changed to

Electric field of multiple point-charges: Two point charges Q1 and Q2 of equal magnitudes and opposite signs are positioned as shown in the figure. Which of the arrows best represents the net electric field at point P due to these two charges?

Coulomb's law: When two point charges are 2.0 cm apart, each one experiences a 1.0-N electric force due to the other charge. If they are moved to a new separation of 8.0 cm, the electric force on each of them is closest to

Coulomb's law: A positive point charge Q is fixed on a very large horizontal frictionless tabletop. A second positive point charge q is released from rest near the stationary charge and is free to move. Which statement best describes the motion of q after it is released?

Coulomb's law: A 1.0-C point charge is 15 m from a second point charge, and the electric force on one of them due to the other is 1.0 N. What is the magnitude of the second charge? (k = 1/4πε₀ = 8.99 × 10⁹ N ∙ m²/C²)

Electric field of multiple point-charges: The figure shows three electric charges labeled Q₁, Q₂, Q₃, and some electric field lines in the region surrounding the charges. What are the signs of the three charges?

Charge: A piece of plastic has a net charge of +2.00 μC. How many more protons than electrons does this piece of plastic have? (e = 1.60 × 10^-19C)

Coulomb's law: Charge Q₁ = 6.0 nC is at (0.30 m, 0), charge Q₂ = -1.0 nC is at (0, 0.10 m), and charge Q₃ = 5.0 nC is at (0, 0). What are the magnitude and direction of the net electrostatic force on the 5.0-nC charge due to the other charges? (k = 1/4πε₀ = 8.99 × 10⁹ N ∙ m²/C²)

Electric field of multiple point-charges: Two point charges Q₁ and Q₂ of equal magnitudes and opposite signs are positioned as shown in the figure. Which of the arrows best represents the net electric field at point P due to these two charges?