Question 1

A parallel-plate capacitor has a voltage of 391 V applied across its plates,then the voltage source is removed.What is the voltage across its plates if the space between them becomes filled with mica? (The dielectric constant for mica is 5.4 and for air is 1.0006. )

Accepted Answer

A) 72 V 
B) 2110 V 
C) 641 V 
D) 18,675 V

Question 2

Consider the group of charges in this figure.All three charges have Q = 2.4 nC.What is their electric potential energy?

Accepted Answer

A) 4.1 × 10-6 J 
B) 4.6 × 10-6 J 
C) 4.2 × 10-6 J 
D) 4.4 × 10-6 J

Question 3

If the potential is constant on a surface,then any electric field present can only be perpendicular to that surface.

Accepted Answer

A) True 
 B)False

Question 4

A sphere with radius 2.0 mm carries a 1.0 μC charge.What is the potential difference,VB - VA,between point B 4.0 m from the center of the sphere and point A 9.0 m from the center of the sphere? (The value of k is 9.0 F1F1F1S1F1F1F10 109 N·m2/C2. )

Accepted Answer

A) 1300 V 
B) -1300 V 
C) 140 V 
D) -0.45 V

Question 5

Two equal positive charges are separated by a fixed distance.If you put a third positive charge midway between these two charges,its electrical potential energy (relative to infinity)is zero because the electrical forces due to the two fixed charges just balance each other.

Accepted Answer

A) True 
 B)False

Question 6

Two parallel circular plates with radius 7.0 mm carrying equal-magnitude surface charge densities of ±3.0 μC/m2 are separated by a distance of 1.0 mm.How much stored energy do the plates have?

Accepted Answer

A) 78 nJ 
B) 25 nJ 
C) 7.9 nJ 
D) 250 nJ

Question 7

Four charged particles (two having a charge +Q and two having a charge -Q)are distributed on the xy-plane,as shown below.Each charge is equidistant from the origin.The voltage is zero at infinity.The amount of work required to move a positively charged particle from point P to point O (which is on the z-axis,below the origin)is

Accepted Answer

A) zero. 
B) positive. 
C) negative. 
D) dependent on the path in which the charged is moved.

Question 8

A parallel-plate capacitor having circular plates of diameter D and a distance d apart stores energy U when it is connected across a fixed potential difference.If you want to triple the amount of energy stored in this capacitor by changing only the size of its plates,the diameter should be changed to:

Accepted Answer

A) 9D 
B) 3D 
C) D  
D)   
E)

Question 9

Two parallel plates that are initially uncharged are separated by 1.2 mm.What charge must be transferred from one plate to the other if 11.0 kJ of energy are to be stored in the plates? The area of each plate is 19.0 mm2.

Accepted Answer

A) 56 μC 
B) 39 μC 
C) 78 μC 
D) 3.5 mC

Question 10

Suppose a region of space has a uniform electric field,directed toward the right,as shown in the figure.Which statement is true?

Accepted Answer

A) The voltage at all three locations is the same. 
B) The voltage at points A and B are equal,and the voltage at point C is higher than the voltage at point A. 
C) The voltage at points A and B are equal,and the voltage at point C is lower than the voltage at point A. 
D) The voltage at point A is the highest,the voltage at point B is the second highest,and the voltage at point C is the lowest. 
E) None of the above

Question 11

If the electric field is zero everywhere inside a region of space,the potential must also be zero in that region.

Accepted Answer

A) True 
 B)False

Question 12

A charge of 3.0 μC and a second charge are initially far apart.If it takes 29 J of work to bring them to a final configuration in which the 3.0 μC is at x = 1.0 mm,y - 1.0 mm,and the other charge is at x = 1.0 mm,y = 3.0 mm,find the magnitude of the unknown charge.(The value of k is 9.0 F1F1F1S1F1F1F10 109 N·m2/C2. )

Accepted Answer

A) 2.15 μC 
B) 4.30 μC 
C) 10.74 μC 
D) 4.30 nC

Question 13

The potential is zero on the surface of a conductor in electrostatic equilibrium.

Accepted Answer

A) True 
 B)False

Question 14

You want to put an electron somewhere between the plates of a parallel plate capacitor so that it will have the maximum electrical potential energy relative to one of the plates.The best place to put it is at the inner surface of the negative plate.

Accepted Answer

A) True 
 B)False

Question 15

Suppose you have two point charges,+Q and -q.As you pull them farther and farther apart,you increase the potential energy of this system relative to infinity.

Accepted Answer

A) True 
 B)False

Question 16

A proton is accelerated from rest through a potential difference Vo and gains a speed vo.If it were accelerated instead through a potential difference of 2Vo,it would gain a speed:

Accepted Answer

A) 8 vo 
B) 4 vo 
C) 2 vo 
D) vo

Question 17

A parallel-plate capacitor has a potential energy due to its charge of 6.00 mJ.It is accidentally filled with water in such a way as not to discharge its plates.How much energy does it continue to store after it is filled? (The dielectric constant for water is 78 and for air is 1.0006. )

Accepted Answer

A) 0.077 mJ 
B) 468 mJ 
C) 0.04 mJ 
D) 6.00 mJ

Question 18

A parallel plate capacitor contains a positively charged plate on the left,and a negatively charged plate on the right.An electron in between the plates is moving to the right.Which statement is true?

Accepted Answer

A) The potential energy of the electron is increasing and it is moving to a region having a lower potential. 
B) The potential energy of the electron is increasing and it is moving to a region having a higher potential. 
C) The potential energy of the electron is decreasing and it is moving to a region having a lower potential. 
D) The potential energy of the electron is decreasing and it is moving to a region having a higher potential.

Question 19

Two conductors are joined by a long copper wire.Thus

Accepted Answer

A) each conductor carries the same free charge. 
B) each conductor must be at the same potential. 
C) the electric field at the surface of each conductor is the same. 
D) no free charge can be present on either conductor. 
E) the potential on the wire is the average of the potential of each conductor.

Question 20

A 1.0 μF capacitor has a potential difference of 6.0 V applied across its plates.If the potential difference across its plates is increased to 8.0 V,how much additional energy does the capacitor store?

Accepted Answer

A) 14 μJ 
B) 28 μJ 
C) 2.0 μJ 
D) 4.0 μJ

Exam 21: Electric Potential

A parallel-plate capacitor has a voltage of 391 V applied across its plates,then the voltage source is removed.What is the voltage across its plates if the space between them becomes filled with mica? (The dielectric constant for mica is 5.4 and for air is 1.0006. )

Consider the group of charges in this figure.All three charges have Q = 2.4 nC.What is their electric potential energy?

If the potential is constant on a surface,then any electric field present can only be perpendicular to that surface.

A sphere with radius 2.0 mm carries a 1.0 μC charge.What is the potential difference,VB - VA,between point B 4.0 m from the center of the sphere and point A 9.0 m from the center of the sphere? (The value of k is 9.0  109 N·m²/C². )

Two equal positive charges are separated by a fixed distance.If you put a third positive charge midway between these two charges,its electrical potential energy (relative to infinity)is zero because the electrical forces due to the two fixed charges just balance each other.

Two parallel circular plates with radius 7.0 mm carrying equal-magnitude surface charge densities of ±3.0 μC/m² are separated by a distance of 1.0 mm.How much stored energy do the plates have?

Two parallel plates that are initially uncharged are separated by 1.2 mm.What charge must be transferred from one plate to the other if 11.0 kJ of energy are to be stored in the plates? The area of each plate is 19.0 mm².

Suppose a region of space has a uniform electric field,directed toward the right,as shown in the figure.Which statement is true?

If the electric field is zero everywhere inside a region of space,the potential must also be zero in that region.

The potential is zero on the surface of a conductor in electrostatic equilibrium.

You want to put an electron somewhere between the plates of a parallel plate capacitor so that it will have the maximum electrical potential energy relative to one of the plates.The best place to put it is at the inner surface of the negative plate.

Suppose you have two point charges,+Q and -q.As you pull them farther and farther apart,you increase the potential energy of this system relative to infinity.

A proton is accelerated from rest through a potential difference V_o and gains a speed vo.If it were accelerated instead through a potential difference of 2V_o,it would gain a speed:

A parallel-plate capacitor has a potential energy due to its charge of 6.00 mJ.It is accidentally filled with water in such a way as not to discharge its plates.How much energy does it continue to store after it is filled? (The dielectric constant for water is 78 and for air is 1.0006. )

A parallel plate capacitor contains a positively charged plate on the left,and a negatively charged plate on the right.An electron in between the plates is moving to the right.Which statement is true?

Two conductors are joined by a long copper wire.Thus

A 1.0 μF capacitor has a potential difference of 6.0 V applied across its plates.If the potential difference across its plates is increased to 8.0 V,how much additional energy does the capacitor store?

Exam 21: Electric Potential

A parallel-plate capacitor has a voltage of 391 V applied across its plates,then the voltage source is removed.What is the voltage across its plates if the space between them becomes filled with mica? (The dielectric constant for mica is 5.4 and for air is 1.0006. )

Consider the group of charges in this figure.All three charges have Q = 2.4 nC.What is their electric potential energy?

If the potential is constant on a surface,then any electric field present can only be perpendicular to that surface.

A sphere with radius 2.0 mm carries a 1.0 μC charge.What is the potential difference,VB - VA,between point B 4.0 m from the center of the sphere and point A 9.0 m from the center of the sphere? (The value of k is 9.0  109 N·m2/C2. )

Two equal positive charges are separated by a fixed distance.If you put a third positive charge midway between these two charges,its electrical potential energy (relative to infinity)is zero because the electrical forces due to the two fixed charges just balance each other.

Two parallel circular plates with radius 7.0 mm carrying equal-magnitude surface charge densities of ±3.0 μC/m2 are separated by a distance of 1.0 mm.How much stored energy do the plates have?

Two parallel plates that are initially uncharged are separated by 1.2 mm.What charge must be transferred from one plate to the other if 11.0 kJ of energy are to be stored in the plates? The area of each plate is 19.0 mm2.

Suppose a region of space has a uniform electric field,directed toward the right,as shown in the figure.Which statement is true?

If the electric field is zero everywhere inside a region of space,the potential must also be zero in that region.

The potential is zero on the surface of a conductor in electrostatic equilibrium.

You want to put an electron somewhere between the plates of a parallel plate capacitor so that it will have the maximum electrical potential energy relative to one of the plates.The best place to put it is at the inner surface of the negative plate.

Suppose you have two point charges,+Q and -q.As you pull them farther and farther apart,you increase the potential energy of this system relative to infinity.

A proton is accelerated from rest through a potential difference Vo and gains a speed vo.If it were accelerated instead through a potential difference of 2Vo,it would gain a speed:

A parallel-plate capacitor has a potential energy due to its charge of 6.00 mJ.It is accidentally filled with water in such a way as not to discharge its plates.How much energy does it continue to store after it is filled? (The dielectric constant for water is 78 and for air is 1.0006. )

A parallel plate capacitor contains a positively charged plate on the left,and a negatively charged plate on the right.An electron in between the plates is moving to the right.Which statement is true?

Two conductors are joined by a long copper wire.Thus

A 1.0 μF capacitor has a potential difference of 6.0 V applied across its plates.If the potential difference across its plates is increased to 8.0 V,how much additional energy does the capacitor store?

A sphere with radius 2.0 mm carries a 1.0 μC charge.What is the potential difference,VB - VA,between point B 4.0 m from the center of the sphere and point A 9.0 m from the center of the sphere? (The value of k is 9.0  109 N·m²/C². )

Two parallel circular plates with radius 7.0 mm carrying equal-magnitude surface charge densities of ±3.0 μC/m² are separated by a distance of 1.0 mm.How much stored energy do the plates have?

Two parallel plates that are initially uncharged are separated by 1.2 mm.What charge must be transferred from one plate to the other if 11.0 kJ of energy are to be stored in the plates? The area of each plate is 19.0 mm².

A proton is accelerated from rest through a potential difference V_o and gains a speed vo.If it were accelerated instead through a potential difference of 2V_o,it would gain a speed: