Question 1

When the dipole moment of a dipole in a uniform electric field rotates to become more nearly aligned with the field:

Accepted Answer

A) the field does positive work and the potential energy increases 
B) the field does positive work and the potential energy decreases 
C) the field does negative work and the potential energy increases 
D) the field does negative work and the potential energy decreases 
E) the field does no work 
A) the field does positive work and the potential energy increases 
B) the field does positive work and the potential energy decreases 
C) the field does negative work and the potential energy increases 
D) the field does negative work and the potential energy decreases 
E) the field does no work

Question 2

The diagram shows a particle with positive charge Q and a particle with negative charge -Q.The electric field at point P on the perpendicular bisector of the line joining them is:

Accepted Answer

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

Question 3

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 4

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 5

An electric dipole consists of two charges, ±2.5 µC, separated by 1.0 x 10-4 m and centered on the origin.If the dipole is oriented along the x axis, what is the electric field at x = 15 cm?

Accepted Answer

A) 0 N/C 
B) 100 N/C 
C) 200 N/C 
D) 670 N/C 
E) 1300 N/C 
A) 0 N/C 
B) 100 N/C 
C) 200 N/C 
D) 670 N/C 
E) 1300 N/C

Question 6

Electric field lines:

Accepted Answer

A) are trajectories of a test charge 
B) are vectors in the direction of the electric field 
C) form closed loops 
D) cross each other in the region between two point charges 
E) are none of the above 
A) are trajectories of a test charge 
B) are vectors in the direction of the electric field 
C) form closed loops 
D) cross each other in the region between two point charges 
E) are none of the above

Question 7

The electric field due to a uniform distribution of charge on a spherical shell is zero:

Accepted Answer

A) everywhere 
B) nowhere 
C) only at the center of the shell 
D) only inside the shell 
E) only outside the shell 
A) everywhere 
B) nowhere 
C) only at the center of the shell 
D) only inside the shell 
E) only outside the shell

Question 8

A cylinder has a radius of 2.1 cm and a length of 8.8 cm.Total charge 6.1 * 10-7 C is distributed uniformly throughout.The volume charge density is:

Accepted Answer

A) 7.4 * 10-11 C/m3  
B) 5.3*10-5 C/m3 
C) 5.3* 10-5 C/m2 
D) 8.5 *10-4 C/m3 
E) 5.0* 10-3 C/m3 
A) 7.4 * 10-11 C/m3  
B) 5.3*10-5 C/m3 
C) 5.3* 10-5 C/m2 
D) 8.5 *10-4 C/m3 
E) 5.0* 10-3 C/m3

Question 9

An electron traveling north enters a region where the electric field is uniform and points west.The electron:

Accepted Answer

A) speeds up 
B) slows down 
C) veers east 
D) veers west 
E) continues with the same speed in the same direction 
A) speeds up 
B) slows down 
C) veers east 
D) veers west 
E) continues with the same speed in the same direction

Question 10

Comparing the field of a single point charge with the field of an electric dipole,

Accepted Answer

A) the field of the point charge decreases more rapidly with distance 
B) the field of the point charge decreases less rapidly with distance 
C) the field of the point charge decreases more rapidly with distance but only along the dipole axis 
D) the field of the point charge decreases less rapidly with distance but only perpendicular to the dipole axis 
E) the fields decrease equally rapidly with distance 
A) the field of the point charge decreases more rapidly with distance 
B) the field of the point charge decreases less rapidly with distance 
C) the field of the point charge decreases more rapidly with distance but only along the dipole axis 
D) the field of the point charge decreases less rapidly with distance but only perpendicular to the dipole axis 
E) the fields decrease equally rapidly with distance

Question 11

A spherical shell has an inner radius of 3.7 cm and an outer radius of 4.5 cm.If charge is distributed uniformly throughout the shell with a volume density of 6.1*10-4 C/m3 the total charge is:

Accepted Answer

A) 1.0*10-7 C 
B) 1.3*10-7 C 
C) 2.0 * 10-7 C 
D) 1.7* 10-6 C 
E) 5.0 *10-6 C 
A) 1.0*10-7 C 
B) 1.3*10-7 C 
C) 2.0 * 10-7 C 
D) 1.7* 10-6 C 
E) 5.0 *10-6 C

Question 12

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 13

Choose the correct statement concerning electric field lines:

Accepted Answer

A) field lines may cross 
B) field lines are close together where the field is large 
C) field lines point away from negatively charged particle 
D) a point charge particle released from rest moves along a field line 
E) none of these are correct 
A) field lines may cross 
B) field lines are close together where the field is large 
C) field lines point away from negatively charged particle 
D) a point charge particle released from rest moves along a field line 
E) none of these are correct

Question 14

An electric dipole of dipole moment 4.5 x 10-9 C·m is in a 250 N/C electric field.If the electric field points east, and the dipole moment vector points 37° west of south, what is the potential energy?

Accepted Answer

A) -6.8 x 10-8 J 
B) -9.0 x 10-7 J 
C) 0 J 
D) 6.8 x 10-8 J 
E) 9.0 x 10-7 J 
A) -6.8 x 10-8 J 
B) -9.0 x 10-7 J 
C) 0 J 
D) 6.8 x 10-8 J 
E) 9.0 x 10-7 J

Question 15

Two point particles, one with charge +8 *10-9 C and the other with charge-2 *10-9 C, are separated by 4 m.The electric field midway between them is:

Accepted Answer

A) 9 *109 N/C 
B) 13,500 N/C 
C) 135,000 N/C 
D) 36 *10-9 N/C 
E) 22.5 N/C 
A) 9 *109 N/C 
B) 13,500 N/C 
C) 135,000 N/C 
D) 36 *10-9 N/C 
E) 22.5 N/C

Question 16

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.Its dipole moment is:

Accepted Answer

A) 1.8 * 10-8 C.m, in the positive x direction 
B) 1.8 *10-8 C.m, in the negative x direction 
C) 0 C.m, because the net charge is 0 
D) 1.8 * 10-8 C.m, in the positive y direction 
E) 1.8 *10-8 C.m, in the negative y direction 
A) 1.8 * 10-8 C.m, in the positive x direction 
B) 1.8 *10-8 C.m, in the negative x direction 
C) 0 C.m, because the net charge is 0 
D) 1.8 * 10-8 C.m, in the positive y direction 
E) 1.8 *10-8 C.m, in the negative y direction

Question 17

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 18

An isolated point charged point particle produces an electric field with magnitude E at a point 2 m away from the charge.A point at which the field magnitude is E/4 is:

Accepted Answer

A) 0.5 m away from the charge 
B) 1 m away from the charge 
C) 2 m away from the charge 
D) 4 m away from the charge 
E) 8 m away from the charge 
A) 0.5 m away from the charge 
B) 1 m away from the charge 
C) 2 m away from the charge 
D) 4 m away from the charge 
E) 8 m away from the charge

Question 19

Let k denote 1/4 $\pi$$\varepsilon$0.The magnitude of the electric field at a distance r from an isolated point charge q is:

Accepted Answer

A) kq/r 
B) kr/q 
C) kq/r3 
D) kq/r2 
E) kq2/r2 
A) kq/r 
B) kr/q 
C) kq/r3 
D) kq/r2 
E) kq2/r2

Question 20

Charge is placed on the surface of a 2.7-cm radius isolated conducting sphere.The surface charge density is uniform and has the value 6.9 * 10-6 C/m2.The total charge on the sphere is:

Accepted Answer

A) 5.7 * 10-10 C 
B) 1.6 * 10-8 C 
C) 3.2 *10-8 C 
D) 6.3 * 10-8 C 
E) 7.5 *10-4 C 
A) 5.7 * 10-10 C 
B) 1.6 * 10-8 C 
C) 3.2 *10-8 C 
D) 6.3 * 10-8 C 
E) 7.5 *10-4 C

Exam 22: Electric Fields

When the dipole moment of a dipole in a uniform electric field rotates to become more nearly aligned with the field:

The diagram shows a particle with positive charge Q and a particle with negative charge -Q.The electric field at point P on the perpendicular bisector of the line joining them is:

The units of the electric field are:

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

An electric dipole consists of two charges, ±2.5 µC, separated by 1.0 x 10-4 m and centered on the origin.If the dipole is oriented along the x axis, what is the electric field at x = 15 cm?

Electric field lines:

The electric field due to a uniform distribution of charge on a spherical shell is zero:

A cylinder has a radius of 2.1 cm and a length of 8.8 cm.Total charge 6.1 * 10-7 C is distributed uniformly throughout.The volume charge density is:

An electron traveling north enters a region where the electric field is uniform and points west.The electron:

Comparing the field of a single point charge with the field of an electric dipole,

A spherical shell has an inner radius of 3.7 cm and an outer radius of 4.5 cm.If charge is distributed uniformly throughout the shell with a volume density of 6.1*10-4 C/m3 the total charge is:

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

Choose the correct statement concerning electric field lines:

An electric dipole of dipole moment 4.5 x 10-9 C·m is in a 250 N/C electric field.If the electric field points east, and the dipole moment vector points 37° west of south, what is the potential energy?

Two point particles, one with charge +8 *10-9 C and the other with charge-2 *10-9 C, are separated by 4 m.The electric field midway between them 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.Its dipole moment is:

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 isolated point charged point particle produces an electric field with magnitude E at a point 2 m away from the charge.A point at which the field magnitude is E/4 is:

Let k denote 1/4 π\piπε\varepsilonε 0.The magnitude of the electric field at a distance r from an isolated point charge q is:

Charge is placed on the surface of a 2.7-cm radius isolated conducting sphere.The surface charge density is uniform and has the value 6.9 * 10-6 C/m2.The total charge on the sphere is:

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An electric dipole consists of two charges, ±2.5 µC, separated by 1.0 x 10^-4 m and centered on the origin.If the dipole is oriented along the x axis, what is the electric field at x = 15 cm?

A cylinder has a radius of 2.1 cm and a length of 8.8 cm.Total charge 6.1 * 10^-7 C is distributed uniformly throughout.The volume charge density is:

A spherical shell has an inner radius of 3.7 cm and an outer radius of 4.5 cm.If charge is distributed uniformly throughout the shell with a volume density of 6.1*10^-4 C/m³ the total charge is:

An electric dipole of dipole moment 4.5 x 10^-9 C·m is in a 250 N/C electric field.If the electric field points east, and the dipole moment vector points 37° west of south, what is the potential energy?

Two point particles, one with charge +8 10^-9 C and the other with charge-2 10^-9 C, are separated by 4 m.The electric field midway between them 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 -610^-6 C on the x axis at x = 3 10^-3 m.Its dipole moment is:

Let k denote 1/4 $\pi$ $\varepsilon$ ₀.The magnitude of the electric field at a distance r from an isolated point charge q is:

Charge is placed on the surface of a 2.7-cm radius isolated conducting sphere.The surface charge density is uniform and has the value 6.9 * 10^-6 C/m².The total charge on the sphere is: