Question 1

FIGURE 21-6 
-Four point charges of varying magnitude and sign are arranged on the corners of the square of side d as shown in Fig. 21-6. Which of the arrows shown represents the net force acting on the point charge with a charge +Q?

Accepted Answer

The net force on the point charge with a charge +Q is the vector sum of the forces due to the other three charges. The force due to the charge -Q at the top right corner is to the left, the force due to the charge +Q at the bottom right corner is to the right, and the force due to the charge -Q at the bottom left corner is upward. The vector sum of these forces is to the right, which is represented by arrow A.

Question 2

When five equal positive charges are uniformly spaced along the x-axis, the force on the next to last charge on the right is directed

Accepted Answer

The force on the next to last charge on the right is directed to the right because the net force on the charge is the sum of the forces due to the four charges to the left of it, which are all directed to the right.

Question 3

FIGURE 21-8 
-Three equal point charges are placed at the corners of a square of side d as shown in Fig. 21-8. Which of the arrows shown represents the direction of the net electric field at the center of the square?

Accepted Answer

The net electric field at the center of the square is zero because the electric fields due to the three charges cancel each other out.

Question 4

Is it possible to have a zero electric field value between a negative and positive charge along the line joining the two charges?

Accepted Answer

The answer of Is it possible to have a zero...

Question 5

Two charged objects are separated by a distance d. The first charge is larger in magnitude than the second charge.

Accepted Answer

According to Newton's third law of motion, the forces two objects exert on each other are equal in magnitude and opposite in direction, regardless of the magnitudes of the charges.

Question 6

FIGURE 21-7 -Two charges Q₁ and Q₂ of equal magnitudes and opposite signs are positioned as shown in Fig. 21-7. Which of the shown arrows represents correctly the electric field at point P?

Accepted Answer

The electric field at point P is the vector sum of the electric fields due to Q1 and Q2. The electric field due to Q1 is directed towards Q1, and the electric field due to Q2 is directed towards Q2. Since Q1 and Q2 are equal in magnitude and opposite in sign, the electric fields due to Q1 and Q2 cancel each other out at point P. Therefore, the electric field at point P is zero.

Question 7

A long line of charge with charge per unit length λ1 is located on the x-axis and another long line of charge with charge per unit length λ2 is located on the y-axis with their centers crossing at the origin. In what direction is the electric field at point z = a on the positive z-axis if λ1 and λ2 are positive?

Accepted Answer

The electric field due to each line of charge is directed radially outward from the line. At point z = a on the positive z-axis, the fields from both lines will have components in the positive z-direction, resulting in a net electric field in the positive z-direction.

Question 8

Four equal negative point charges are located at the corners of a square, their positions in the x-y plane being (1, 1), (-1, 1), (-1, -1), (1,-1). The direction of the electric field on the x-axis at (1, 0) is

Accepted Answer

The answer of Four equal negative point charges are located...

Question 9

FIGURE 21-2 
-Four point charges of equal magnitudes but with varying signs are arranged on three of the corners and at the center of the square of side d as shown in Fig. 21-2. Which of the arrows shown represents the net force acting on the center charge?

Accepted Answer

The net force on the center charge is the vector sum of the forces due to the other three charges. The forces due to the charges at the corners are equal in magnitude and opposite in direction, so they cancel out. The force due to the charge at the center is repulsive and points away from the center. Therefore, the net force on the center charge is repulsive and points away from the center, which is represented by arrow A.

Question 10

Two large, flat, horizontally oriented plates are parallel to each other, a distance d apart. Half-way between the two plates the electric field field has a 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 two parallel plates is uniform and independent of the distance between the plates. Therefore, reducing the separation does not change the magnitude of the electric field halfway between the plates.

Question 11

FIGURE 21-4 
-Four point charges of equal magnitude and varying signs are arranged on corners of the square of side d as shown in Fig. 21-4. Which of the arrows shown represents the net force acting on the charge at the upper right hand corner of the square?

Accepted Answer

The answer of FIGURE 21-4 
-Four point charges of equal...

Question 12

Equal charges are located at the vertices of a 3-4-5 triangle. The charge experiencing the largest force is located at

Accepted Answer

The answer of Equal charges are located at the vertices...

Question 13

FIGURE 21-9 
-Three equal point charges are placed at three of the corners of a square of side d as shown in Fig. 21-9. Which of the arrows shown represents the direction of the net electric field at the center of the square?

Accepted Answer

The answer of FIGURE 21-9 
-Three equal point charges are...

Question 14

FIGURE 21-5 
-Four point charges of equal magnitude and sign are arranged on the corners of the square of side d as shown in Fig. 21-5. Which of the arrows shown represents the net force acting on the charge at the upper right hand corner of the square?

Accepted Answer

The answer of FIGURE 21-5 
-Four point charges of equal...

Question 15

In deriving the axial electric field for the ring-shaped charge distribution and the electric field from a long line of charge, the component perpendicular to the resulting field is zero because of what physical property?

Accepted Answer

The perpendicular components of the electric field cancel out due to the symmetry of the charge distribution, leaving only the axial component.

Question 16

Is it possible to have a zero electric field value between two positive charges along the line joining the two charges?

Accepted Answer

The answer of Is it possible to have a zero...

Question 17

FIGURE 21-1 
-Three equal charges are at three of the corners of a square of side d. A fourth charge of equal magnitude is at the center of the square as shown in Fig. 21-1. Which of the arrows shown represents the net force acting on the charge at the center of the square?

Accepted Answer

The answer of FIGURE 21-1 
-Three equal charges are at...

Question 18

FIGURE 21-10 
-Which of the arrows shown in Fig. 21-10 represents the correct direction of the electric field between the two metal plates?

Accepted Answer

The electric field between two metal plates is always perpendicular to the plates. In this case, the electric field is pointing from the positive plate to the negative plate, so the correct answer is A.

Question 19

FIGURE 21-3 
-Four point charges of equal magnitude but with varying signs are arranged on three of the corners and at the center of the square of side d as shown in Fig. 21-3. Which of the arrows shown represents the net force acting on the center charge?

Accepted Answer

The net force on the center charge is the vector sum of the forces due to the other three charges. The forces due to the charges at the corners are equal in magnitude and opposite in direction, so they cancel out. The force due to the charge at the center is repulsive and directed away from the center. Therefore, the net force on the center charge is repulsive and directed away from the center, which is represented by arrow A.

Question 20

The direction of the electric field halfway between an electron and a proton is

Accepted Answer

The electric field is directed from positive to negative charges. Since the proton is positive and the electron is negative, the field halfway between them is directed toward the electron.

Quiz 21: Electric Charge and Electric Field

FIGURE 21-6 -Four point charges of varying magnitude and sign are arranged on the corners of the square of side d as shown in Fig. 21-6. Which of the arrows shown represents the net force acting on the point charge with a charge +Q?

When five equal positive charges are uniformly spaced along the x-axis, the force on the next to last charge on the right is directed

FIGURE 21-8 -Three equal point charges are placed at the corners of a square of side d as shown in Fig. 21-8. Which of the arrows shown represents the direction of the net electric field at the center of the square?

Is it possible to have a zero electric field value between a negative and positive charge along the line joining the two charges?

Two charged objects are separated by a distance d. The first charge is larger in magnitude than the second charge.

FIGURE 21-7 -Two charges Q₁ and Q₂ of equal magnitudes and opposite signs are positioned as shown in Fig. 21-7. Which of the shown arrows represents correctly the electric field at point P?

Four equal negative point charges are located at the corners of a square, their positions in the x-y plane being (1, 1) , (-1, 1) , (-1, -1) , (1,-1) . The direction of the electric field on the x-axis at (1, 0) is

FIGURE 21-2 -Four point charges of equal magnitudes but with varying signs are arranged on three of the corners and at the center of the square of side d as shown in Fig. 21-2. Which of the arrows shown represents the net force acting on the center charge?

Two large, flat, horizontally oriented plates are parallel to each other, a distance d apart. Half-way between the two plates the electric field field has a 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?

FIGURE 21-4 -Four point charges of equal magnitude and varying signs are arranged on corners of the square of side d as shown in Fig. 21-4. Which of the arrows shown represents the net force acting on the charge at the upper right hand corner of the square?

Equal charges are located at the vertices of a 3-4-5 triangle. The charge experiencing the largest force is located at

FIGURE 21-9 -Three equal point charges are placed at three of the corners of a square of side d as shown in Fig. 21-9. Which of the arrows shown represents the direction of the net electric field at the center of the square?

FIGURE 21-5 -Four point charges of equal magnitude and sign are arranged on the corners of the square of side d as shown in Fig. 21-5. Which of the arrows shown represents the net force acting on the charge at the upper right hand corner of the square?

In deriving the axial electric field for the ring-shaped charge distribution and the electric field from a long line of charge, the component perpendicular to the resulting field is zero because of what physical property?

Is it possible to have a zero electric field value between two positive charges along the line joining the two charges?

FIGURE 21-1 -Three equal charges are at three of the corners of a square of side d. A fourth charge of equal magnitude is at the center of the square as shown in Fig. 21-1. Which of the arrows shown represents the net force acting on the charge at the center of the square?

FIGURE 21-10 -Which of the arrows shown in Fig. 21-10 represents the correct direction of the electric field between the two metal plates?

FIGURE 21-3 -Four point charges of equal magnitude but with varying signs are arranged on three of the corners and at the center of the square of side d as shown in Fig. 21-3. Which of the arrows shown represents the net force acting on the center charge?

The direction of the electric field halfway between an electron and a proton is

Quiz 21: Electric Charge and Electric Field

FIGURE 21-6 -Four point charges of varying magnitude and sign are arranged on the corners of the square of side d as shown in Fig. 21-6. Which of the arrows shown represents the net force acting on the point charge with a charge +Q?

When five equal positive charges are uniformly spaced along the x-axis, the force on the next to last charge on the right is directed

FIGURE 21-8 -Three equal point charges are placed at the corners of a square of side d as shown in Fig. 21-8. Which of the arrows shown represents the direction of the net electric field at the center of the square?

Is it possible to have a zero electric field value between a negative and positive charge along the line joining the two charges?

Two charged objects are separated by a distance d. The first charge is larger in magnitude than the second charge.

FIGURE 21-7 -Two charges Q1 and Q2 of equal magnitudes and opposite signs are positioned as shown in Fig. 21-7. Which of the shown arrows represents correctly the electric field at point P?

Four equal negative point charges are located at the corners of a square, their positions in the x-y plane being (1, 1) , (-1, 1) , (-1, -1) , (1,-1) . The direction of the electric field on the x-axis at (1, 0) is

FIGURE 21-2 -Four point charges of equal magnitudes but with varying signs are arranged on three of the corners and at the center of the square of side d as shown in Fig. 21-2. Which of the arrows shown represents the net force acting on the center charge?

Two large, flat, horizontally oriented plates are parallel to each other, a distance d apart. Half-way between the two plates the electric field field has a 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?

FIGURE 21-4 -Four point charges of equal magnitude and varying signs are arranged on corners of the square of side d as shown in Fig. 21-4. Which of the arrows shown represents the net force acting on the charge at the upper right hand corner of the square?

Equal charges are located at the vertices of a 3-4-5 triangle. The charge experiencing the largest force is located at

FIGURE 21-9 -Three equal point charges are placed at three of the corners of a square of side d as shown in Fig. 21-9. Which of the arrows shown represents the direction of the net electric field at the center of the square?

FIGURE 21-5 -Four point charges of equal magnitude and sign are arranged on the corners of the square of side d as shown in Fig. 21-5. Which of the arrows shown represents the net force acting on the charge at the upper right hand corner of the square?

In deriving the axial electric field for the ring-shaped charge distribution and the electric field from a long line of charge, the component perpendicular to the resulting field is zero because of what physical property?

Is it possible to have a zero electric field value between two positive charges along the line joining the two charges?

FIGURE 21-1 -Three equal charges are at three of the corners of a square of side d. A fourth charge of equal magnitude is at the center of the square as shown in Fig. 21-1. Which of the arrows shown represents the net force acting on the charge at the center of the square?

FIGURE 21-10 -Which of the arrows shown in Fig. 21-10 represents the correct direction of the electric field between the two metal plates?

FIGURE 21-3 -Four point charges of equal magnitude but with varying signs are arranged on three of the corners and at the center of the square of side d as shown in Fig. 21-3. Which of the arrows shown represents the net force acting on the center charge?

The direction of the electric field halfway between an electron and a proton is

FIGURE 21-7 -Two charges Q₁ and Q₂ of equal magnitudes and opposite signs are positioned as shown in Fig. 21-7. Which of the shown arrows represents correctly the electric field at point P?