Question 1

A total charge of 6.3 * 10-8 C is distributed uniformly throughout a 2.7-cm radius sphere. The volume charge density is:

Accepted Answer

A)  3.7 *10-7 C/m3 
B)  6.9* 10-6 C/m3 
C)  6.9 *10-6 C/m2 
D)  2.5*10-4 C/m3 
E)  7.6*10-4 C/m3 
A)  3.7 *10-7 C/m3 
B)  6.9* 10-6 C/m3 
C)  6.9 *10-6 C/m2 
D)  2.5*10-4 C/m3 
E)  7.6*10-4 C/m3

Question 2

Experimenter A uses a test charge q0 and experimenter B uses a test charge 2q0 to measure an electric field produced by stationary charges. A finds a field that is:

Accepted Answer

A)  the same as the field found by B 
B)  greater than the field found by B 
C)  less than the field found by B 
D)  either greater or less than the field found by B, depending on the masses of the test charges 
E)  either greater or less than the field found by B, depending on the accelerations of the test charges 
A)  the same as the field found by B 
B)  greater than the field found by B 
C)  less than the field found by B 
D)  either greater or less than the field found by B, depending on the masses of the test charges 
E)  either greater or less than the field found by B, depending on the accelerations of the test charges

Question 3

A certain physics textbook shows a region of space in which two electric field lines cross each other. We conclude that:

Accepted Answer

A)  at least two point charges are present 
B)  an electrical conductor is present 
C)  an insulator is present 
D)  the field points in two directions at the same place 
E)  the author made a mistake 
A)  at least two point charges are present 
B)  an electrical conductor is present 
C)  an insulator is present 
D)  the field points in two directions at the same place 
E)  the author made a mistake

Question 4

As used in the definition of electric field, a "test charge":

Accepted Answer

A)  has zero charge 
B)  must be a proton 
C)  has charge of magnitude 1.6 *10-19 C 
D)  must be an electron 
E)  none of the above 
A)  has zero charge 
B)  must be a proton 
C)  has charge of magnitude 1.6 *10-19 C 
D)  must be an electron 
E)  none of the above

Question 5

Two point charges are arranged as shown. In which region could a third charge +1 C be placed so that the net electrostatic force on it is zero?

Accepted Answer

A)  I only 
B)  I and II only 
C)  III only 
D)  I and III only 
E)  II only 
A)  I only 
B)  I and II only 
C)  III only 
D)  I and III only 
E)  II only

Question 6

Positive charge +Q is uniformly distributed on the upper half of a semicircular rod and negative charge -Q is uniformly distributed on the lower half. What is the direction of the electric field at point P, the center of the semicircle?

Accepted Answer

A)  $\uparrow$ 
B)  $\downarrow$ 
C) $\leftarrow$ 
D)  $\rightarrow$ 
E)    
A)  $\uparrow$ 
B)  $\downarrow$ 
C) $\leftarrow$ 
D)  $\rightarrow$ 
E)

Question 7

A disk with a uniform positive surface charge density lies in the x-y plane, centered on the origin. Along the positive z axis, the direction of the electric field is:

Accepted Answer

A)  in the +z direction 
B)  in the -z direction 
C)  in the +x direction 
D)  in the +y direction 
E)  there is no field along the positive z axis 
A)  in the +z direction 
B)  in the -z direction 
C)  in the +x direction 
D)  in the +y direction 
E)  there is no field along the positive z axis

Question 8

An electric dipole consists of a particle with a charge of +6 *10-6 C at the origin and a particle with a charge of -6 *10-6 C on the x axis at x = 3 *10-3 m. The direction of the electric field due to the dipole at points on the x axis is:

Accepted Answer

A)  in the positive x direction 
B)  in the negative x direction 
C)  in the positive y direction 
D)  in the negative y direction 
E)  in the positive x direction between the charges and in the negative x direction elsewhere 
A)  in the positive x direction 
B)  in the negative x direction 
C)  in the positive y direction 
D)  in the negative y direction 
E)  in the positive x direction between the charges and in the negative x direction elsewhere

Question 9

Positive charge Q is uniformly distributed on a semicircular rod. What is the direction of the electric field at point P, the center of the semicircle?

Accepted Answer

A)  $\uparrow$ 
B)  $\downarrow$ 
C)  $\leftarrow$ 
D) $\rightarrow$ 
E)    
A)  $\uparrow$ 
B)  $\downarrow$ 
C)  $\leftarrow$ 
D) $\rightarrow$ 
E)

Question 10

The diagrams show four possible orientations of an electric dipole in a uniform electric field Rank them according to the magnitude of the torque exerted on the dipole by the field, least to greatest.

Accepted Answer

A)  1, 2, 3, 4 
B)  4, 3, 2, 1 
C)  1, 2, 4, 3 
D)  3, then 2 and 4 tie, then 1 
E)  1, then 2 and 4 tie, then 3 
A)  1, 2, 3, 4 
B)  4, 3, 2, 1 
C)  1, 2, 4, 3 
D)  3, then 2 and 4 tie, then 1 
E)  1, then 2 and 4 tie, then 3

Question 11

An electric field exerts a torque on a dipole only if:

Accepted Answer

A)  the field is parallel to the dipole moment 
B)  the field is not parallel to the dipole moment 
C)  the field is perpendicular to the dipole moment 
D)  the field is not perpendicular to the dipole moment 
E)  the field is uniform 
A)  the field is parallel to the dipole moment 
B)  the field is not parallel to the dipole moment 
C)  the field is perpendicular to the dipole moment 
D)  the field is not perpendicular to the dipole moment 
E)  the field is uniform

Question 12

The units of the electric field are:

Accepted Answer

A)  J/(C.m) 
B)  J/C 
C)  J.C 
D)  J/m 
E)  none of these 
A)  J/(C.m) 
B)  J/C 
C)  J.C 
D)  J/m 
E)  none of these

Question 13

Two point particles, with charges of q1 and q2, are placed a distance r apart. The electric field is zero at a point P between the particles on the line segment connecting them. We conclude that:

Accepted Answer

A)  q1 and q2 must have the same magnitude and sign 
B)  P must be midway between the particles 
C)  q1 and q2 must have the same sign but may have different magnitudes 
D)  q1 and q2 must have equal magnitudes and opposite signs 
E)  q1 and q2 must have opposite signs and may have different magnitudes 
A)  q1 and q2 must have the same magnitude and sign 
B)  P must be midway between the particles 
C)  q1 and q2 must have the same sign but may have different magnitudes 
D)  q1 and q2 must have equal magnitudes and opposite signs 
E)  q1 and q2 must have opposite signs and may have different magnitudes

Question 14

The diagrams below depict four different charge distributions. The charged particles are all the same distance from the origin. The electric field at the origin:

Accepted Answer

A)  is least for situation 1 
B)  is greatest for situation 3 
C)  is zero for situation 4 
D)  is downward for situation 1 
E)  is downward for situation 3 
A)  is least for situation 1 
B)  is greatest for situation 3 
C)  is zero for situation 4 
D)  is downward for situation 1 
E)  is downward for situation 3

Question 15

Positive charge +Q is uniformly distributed on the upper half of a rod and a negative charge -Q is uniformly distributed on the lower half. What is the direction of the electric field at point P, on the perpendicular bisector of the rod?

Accepted Answer

A) $\uparrow$ 
B)  $\downarrow$ 
C)  $\rightarrow$ 
D) $\leftarrow$ 
E)    
A) $\uparrow$ 
B)  $\downarrow$ 
C)  $\rightarrow$ 
D) $\leftarrow$ 
E)

Question 16

The dipole moment of a dipole in a 300-N/C electric field is initially perpendicular to the field, but it rotates so it is in the same direction as the field. If the moment has a magnitude of 2 *10-9 C.m the work done by the field is:

Accepted Answer

A)  -12 * 10-7 J 
B)  -6 *10-7 J 
C)  0 J 
D)  6 *10-7 J 
E)  12 *10-7 J 
A)  -12 * 10-7 J 
B)  -6 *10-7 J 
C)  0 J 
D)  6 *10-7 J 
E)  12 *10-7 J

Question 17

The diagram shows the electric field lines due to two charged parallel metal plates. We conclude that:

Accepted Answer

A)  the upper plate is positive and the lower plate is negative 
B)  a proton at X would experience the same force if it were placed at Y 
C)  a proton at X experiences a greater force than if it were placed at Z 
D)  a proton at X experiences less force than if it were placed at Z 
E)  an electron at X could have its weight balanced by the electrical force 
A)  the upper plate is positive and the lower plate is negative 
B)  a proton at X would experience the same force if it were placed at Y 
C)  a proton at X experiences a greater force than if it were placed at Z 
D)  a proton at X experiences less force than if it were placed at Z 
E)  an electron at X could have its weight balanced by the electrical force

Question 18

The magnitude of the force of a 400-N/C electric field on a 0.02-C point charge is:

Accepted Answer

A)  8 N 
B)  5* 10-5 N 
C)  8 * 10-3 N 
D)  0.08 N 
E)  2 * 103 N 
A)  8 N 
B)  5* 10-5 N 
C)  8 * 10-3 N 
D)  0.08 N 
E)  2 * 103 N

Question 19

Two protons (p1 and p2) are on the x axis, as shown below. The directions of the electric field at points 1, 2, and 3 respectively, are:

Accepted Answer

A)  $\rightarrow$, $\leftarrow$ , $\rightarrow$ 
B)  $\leftarrow$ , $\rightarrow$, $\leftarrow$ 
C)  $\leftarrow$ , $\rightarrow$, $\rightarrow$ 
D)  $\leftarrow$ , $\leftarrow$ , $\leftarrow$ 
E)  $\leftarrow$ , $\leftarrow$ , $\rightarrow$ 
A)  $\rightarrow$, $\leftarrow$ , $\rightarrow$ 
B)  $\leftarrow$ , $\rightarrow$, $\leftarrow$ 
C)  $\leftarrow$ , $\rightarrow$, $\rightarrow$ 
D)  $\leftarrow$ , $\leftarrow$ , $\leftarrow$ 
E)  $\leftarrow$ , $\leftarrow$ , $\rightarrow$

Question 20

The force exerted by a uniform electric field on a dipole is:

Accepted Answer

A)  parallel to the dipole moment 
B)  perpendicular to the dipole moment 
C)  parallel to the electric field 
D)  perpendicular to the electric field 
E)  none of the above 
A)  parallel to the dipole moment 
B)  perpendicular to the dipole moment 
C)  parallel to the electric field 
D)  perpendicular to the electric field 
E)  none of the above

Exam 22: Electric Fields

A total charge of 6.3 * 10-8 C is distributed uniformly throughout a 2.7-cm radius sphere. The volume charge density is:

Experimenter A uses a test charge q0 and experimenter B uses a test charge 2q0 to measure an electric field produced by stationary charges. A finds a field that is:

A certain physics textbook shows a region of space in which two electric field lines cross each other. We conclude that:

As used in the definition of electric field, a "test charge":

Two point charges are arranged as shown. In which region could a third charge +1 C be placed so that the net electrostatic force on it is zero?

Positive charge +Q is uniformly distributed on the upper half of a semicircular rod and negative charge -Q is uniformly distributed on the lower half. What is the direction of the electric field at point P, the center of the semicircle?

A disk with a uniform positive surface charge density lies in the x-y plane, centered on the origin. Along the positive z axis, the direction of the electric field is:

An electric dipole consists of a particle with a charge of +6 *10-6 C at the origin and a particle with a charge of -6 *10-6 C on the x axis at x = 3 *10-3 m. The direction of the electric field due to the dipole at points on the x axis is:

Positive charge Q is uniformly distributed on a semicircular rod. What is the direction of the electric field at point P, the center of the semicircle?

The diagrams show four possible orientations of an electric dipole in a uniform electric field Rank them according to the magnitude of the torque exerted on the dipole by the field, least to greatest.

An electric field exerts a torque on a dipole only if:

The units of the electric field are:

Two point particles, with charges of q1 and q2, are placed a distance r apart. The electric field is zero at a point P between the particles on the line segment connecting them. We conclude that:

The diagrams below depict four different charge distributions. The charged particles are all the same distance from the origin. The electric field at the origin:

Positive charge +Q is uniformly distributed on the upper half of a rod and a negative charge -Q is uniformly distributed on the lower half. What is the direction of the electric field at point P, on the perpendicular bisector of the rod?

The dipole moment of a dipole in a 300-N/C electric field is initially perpendicular to the field, but it rotates so it is in the same direction as the field. If the moment has a magnitude of 2 *10-9 C.m the work done by the field is:

The diagram shows the electric field lines due to two charged parallel metal plates. We conclude that:

The magnitude of the force of a 400-N/C electric field on a 0.02-C point charge is:

Two protons (p1 and p2) are on the x axis, as shown below. The directions of the electric field at points 1, 2, and 3 respectively, are:

The force exerted by a uniform electric field on a dipole is:

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A total charge of 6.3 * 10^-8 C is distributed uniformly throughout a 2.7-cm radius sphere. The volume charge density is:

Experimenter A uses a test charge q₀ and experimenter B uses a test charge 2q₀ to measure an electric field produced by stationary charges. A finds a field that is:

An electric dipole consists of a particle with a charge of +6 10^-6 C at the origin and a particle with a charge of -6 10^-6 C on the x axis at x = 3 *10^-3 m. The direction of the electric field due to the dipole at points on the x axis is:

Two point particles, with charges of q₁ and q₂, are placed a distance r apart. The electric field is zero at a point P between the particles on the line segment connecting them. We conclude that:

The dipole moment of a dipole in a 300-N/C electric field is initially perpendicular to the field, but it rotates so it is in the same direction as the field. If the moment has a magnitude of 2 *10^-9 C.m the work done by the field is:

Two protons (p₁ and p₂) are on the x axis, as shown below. The directions of the electric field at points 1, 2, and 3 respectively, are: