Question 1

A hydrogen nucleus,which has a charge e,is situated to the left of a carbon nucleus,which has a charge 6e.Which statement is true?

Accepted Answer

A) The electrical force experienced by the hydrogen nucleus is to the left,and the magnitude is equal to the force exerted on the carbon nucleus. 
B) The electrical force experienced by the hydrogen nucleus is to the left,and the magnitude is greater than the force exerted on the carbon nucleus. 
C) The electrical force experienced by the hydrogen nucleus is to the left,and the magnitude is less than the force exerted on the carbon nucleus. 
D) The electrical force experienced by the hydrogen nucleus is to the right,and the magnitude is equal to the force exerted on the carbon nucleus. 
A) The electrical force experienced by the hydrogen nucleus is to the left,and the magnitude is equal to the force exerted on the carbon nucleus. 
B) The electrical force experienced by the hydrogen nucleus is to the left,and the magnitude is greater than the force exerted on the carbon nucleus. 
C) The electrical force experienced by the hydrogen nucleus is to the left,and the magnitude is less than the force exerted on the carbon nucleus. 
D) The electrical force experienced by the hydrogen nucleus is to the right,and the magnitude is equal to the force exerted on the carbon nucleus. A

Question 2

A small glass bead has been charged to 8.0 nC? What is the strength of the electric field 2.0 cm from the center of the bead?

Accepted Answer

A) 1.8 × 105 N/C 
B) 3.6 × 103 N/C 
C) 1.4 × 10-3 N/C 
D) 3.6 × 10-6 N/C 
A) 1.8 × 105 N/C 
B) 3.6 × 103 N/C 
C) 1.4 × 10-3 N/C 
D) 3.6 × 10-6 N/C A

Question 3

Two equal and opposite charges a certain distance apart are called an electric "dipole." A positive test charge +q is placed as shown,equidistant from the two charges.   Which diagram below gives the direction of the net force on the test charge?

Accepted Answer

A) 
  
B) 
  
C)    
D)    
A) 
  
B) 
  
C)    
D)    C

Question 4

Two equally charged spheres of mass 1.0 g are placed 2.0 cm apart.When released,they begin to accelerate at 414 m/s2.What is the magnitude of the charge on each sphere?

Accepted Answer

A) 140 nC 
B) 120 nC 
C) 95 nC 
D) 75 nC 
A) 140 nC 
B) 120 nC 
C) 95 nC 
D) 75 nC

Question 5

A plastic rod is charged up by rubbing a wool cloth,and brought to an initially neutral metallic sphere.It is allowed to touch the sphere for a few seconds,and then is separated from the sphere by a small distance.After the rod is separated,the rod

Accepted Answer

A) is repelled by the sphere. 
B) is attracted to the sphere. 
C) feels no force due to the sphere. 
A) is repelled by the sphere. 
B) is attracted to the sphere. 
C) feels no force due to the sphere.

Question 6

Two protons slightly separated from one another form an electric dipole.

Accepted Answer

A) True 
 B)False

Question 7

Two identically charged balls are a certain distance apart.The vectors in the diagram below show the magnitude and direction of the electrostatic force on each ball.   Suppose the charge on the left ball is now doubled (represented by two plus signs).Which diagram below best represents the forces that now act on the two balls?

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
A) 
  
B) 
  
C) 
  
D)

Question 8

A positive test charge q is released near a positive fixed charge Q.   As q moves away from Q,it will move with

Accepted Answer

A) constant velocity. 
B) constant acceleration. 
C) increasing acceleration. 
D) decreasing acceleration. 
A) constant velocity. 
B) constant acceleration. 
C) increasing acceleration. 
D) decreasing acceleration.

Question 9

If the electric field strength is 900 N/C at a point 5 cm from an infinite plane of charge,its strength will be reduced to 9 N/C at a point 50 cm from the plane.

Accepted Answer

A) True 
 B)False

Question 10

Three charges of magnitude 3.0 F1F1F1S1F1F1F10 10-4 C each are located at x = 1.0 m,y = 1.0 m,at s = 0.0 m,y = 0.0 m,and at x = -1.0 m,y = 0.0 m.The one in the middle is negative,while the other two are positive.What is the net Coulombic force exerted by them on a negative 3.0 F1F1F1S1F1F1F10 10-5 C charge located at x = 0.0 m,y = 2.0 m? (The value of k is 9.0 × 109 N·m2/C2. )

Accepted Answer

A) 87 N attractive 
B) 87 N repulsive 
C) 120 N attractive 
D) 120 N repulsive 
A) 87 N attractive 
B) 87 N repulsive 
C) 120 N attractive 
D) 120 N repulsive

Question 11

A metal sphere is insulated electrically and is given a charge.If 25 electrons are added to the sphere in giving a charge,how many Coulombs are added to the sphere?

Accepted Answer

A) - 4.0 × 10-18 C 
B) - 4.0 × 10-20 C 
C) - 40 C 
D) - 25 C 
A) - 4.0 × 10-18 C 
B) - 4.0 × 10-20 C 
C) - 40 C 
D) - 25 C

Question 12

The charge at the bottom of the figure is Q = + 17 nC.What is the magnitude of the force   on the charge Q?

Accepted Answer

A) 1.9 × 10-4 N 
B) 1.2 × 10-4 N 
C) 1.6 × 10-4 N 
D) 2.3 × 10-4 N 
A) 1.9 × 10-4 N 
B) 1.2 × 10-4 N 
C) 1.6 × 10-4 N 
D) 2.3 × 10-4 N

Question 13

Two like charges of the same magnitude are 5.0 mm apart.If the force of repulsion they exert upon each other is 2.0 N,what is the magnitude of each charge? (The constant of proportionality for the Coulombic force is 9.0 × 109 N·m2/C2. )

Accepted Answer

A) 7.5 × 10-2 C 
B) 7.5 × 10-8 C 
C) 7.2 × 102 C 
D) 7.5 × 10-5 C 
A) 7.5 × 10-2 C 
B) 7.5 × 10-8 C 
C) 7.2 × 102 C 
D) 7.5 × 10-5 C

Question 14

A small piece of aluminum (atomic number 13)contains 1015 atoms.(The atomic number is the number of protons;it determines the (positive)electric charge of the nucleus and,thus,the number of electrons in a neutral atom. )If the piece of aluminum has a net positive charge of 3.0 μC,what fraction of the electrons that the aluminum had when it was neutral would have had to be lost?

Accepted Answer

A)    
B)    
C) 1.9 × 10-20 
D) 1.4 × 10-21 
A)    
B)    
C) 1.9 × 10-20 
D) 1.4 × 10-21

Question 15

If the electric field strength is 500 N/C at a point 2 cm from an infinite line of charge,the field will be 125 N/C at a point 4 cm from this line.

Accepted Answer

A) True 
 B)False

Question 16

Suppose a van de Graaff generator builds a negative static charge,and a grounded conductor is placed near enough to it so that a 7.0 μC of negative charge arcs to the conductor.Calculate the number of electrons that are transferred.

Accepted Answer

A) 4.38 × 1013 
B) 7.0 
C) 1.12 × 10-18 
D) 43.8 
A) 4.38 × 1013 
B) 7.0 
C) 1.12 × 10-18 
D) 43.8

Question 17

An asteroid has acquired a net charge of 105 C from being bombarded by the solar wind over the years,and is currently in equilibrium whereby it expels electrons at the same rate as it acquires them.How many more electrons does it have than protons?

Accepted Answer

A) 6.56 × 1020 
B) 656 
C) 630 
D) 1.05 × 10-17 
A) 6.56 × 1020 
B) 656 
C) 630 
D) 1.05 × 10-17

Question 18

One charged plastic ball is vertically above another in a test tube as shown.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

A)    d. 
B) 2d. 
C) 4d. 
D) 8d. 
A)    d. 
B) 2d. 
C) 4d. 
D) 8d.

Question 19

What is the magnitude of an electric field that balances the weight of a plastic sphere of mass 6.4 g that has been charged to -3.0 nC?

Accepted Answer

A) 2.1 × 107 N/C 
B) 2.4 × 106 N/C 
C) 4.5 × 106 N/C 
D) 6.4 × 106 N/C 
A) 2.1 × 107 N/C 
B) 2.4 × 106 N/C 
C) 4.5 × 106 N/C 
D) 6.4 × 106 N/C

Question 20

Two point charges,Q1 = -1.0 μC and Q2 = +3.0 μC,are placed as shown.In the figure,the number of excess electrons in charge Q1 is closest to:

Accepted Answer

A) 6.3 × 1012 
B) 6.3 × 1013 
C) 2.0 × 1011 
D) 2.0 × 1012 
E) 2.0 × 1013 
A) 6.3 × 1012 
B) 6.3 × 1013 
C) 2.0 × 1011 
D) 2.0 × 1012 
E) 2.0 × 1013

Exam 20: Electric Fields and Forces

A hydrogen nucleus,which has a charge e,is situated to the left of a carbon nucleus,which has a charge 6e.Which statement is true?

A small glass bead has been charged to 8.0 nC? What is the strength of the electric field 2.0 cm from the center of the bead?

Two equal and opposite charges a certain distance apart are called an electric "dipole." A positive test charge +q is placed as shown,equidistant from the two charges. Which diagram below gives the direction of the net force on the test charge?

Two equally charged spheres of mass 1.0 g are placed 2.0 cm apart.When released,they begin to accelerate at 414 m/s2.What is the magnitude of the charge on each sphere?

A plastic rod is charged up by rubbing a wool cloth,and brought to an initially neutral metallic sphere.It is allowed to touch the sphere for a few seconds,and then is separated from the sphere by a small distance.After the rod is separated,the rod

Two protons slightly separated from one another form an electric dipole.

A positive test charge q is released near a positive fixed charge Q. As q moves away from Q,it will move with

If the electric field strength is 900 N/C at a point 5 cm from an infinite plane of charge,its strength will be reduced to 9 N/C at a point 50 cm from the plane.

A metal sphere is insulated electrically and is given a charge.If 25 electrons are added to the sphere in giving a charge,how many Coulombs are added to the sphere?

The charge at the bottom of the figure is Q = + 17 nC.What is the magnitude of the force on the charge Q?

Two like charges of the same magnitude are 5.0 mm apart.If the force of repulsion they exert upon each other is 2.0 N,what is the magnitude of each charge? (The constant of proportionality for the Coulombic force is 9.0 × 109 N·m2/C2. )

If the electric field strength is 500 N/C at a point 2 cm from an infinite line of charge,the field will be 125 N/C at a point 4 cm from this line.

Suppose a van de Graaff generator builds a negative static charge,and a grounded conductor is placed near enough to it so that a 7.0 μC of negative charge arcs to the conductor.Calculate the number of electrons that are transferred.

An asteroid has acquired a net charge of 105 C from being bombarded by the solar wind over the years,and is currently in equilibrium whereby it expels electrons at the same rate as it acquires them.How many more electrons does it have than protons?

One charged plastic ball is vertically above another in a test tube as shown.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

What is the magnitude of an electric field that balances the weight of a plastic sphere of mass 6.4 g that has been charged to -3.0 nC?

Two point charges,Q1 = -1.0 μC and Q2 = +3.0 μC,are placed as shown.In the figure,the number of excess electrons in charge Q1 is closest to:

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Two equally charged spheres of mass 1.0 g are placed 2.0 cm apart.When released,they begin to accelerate at 414 m/s².What is the magnitude of the charge on each sphere?

Two like charges of the same magnitude are 5.0 mm apart.If the force of repulsion they exert upon each other is 2.0 N,what is the magnitude of each charge? (The constant of proportionality for the Coulombic force is 9.0 × 10⁹ N·m²/C². )

Two point charges,Q₁ = -1.0 μC and Q₂ = +3.0 μC,are placed as shown.In the figure,the number of excess electrons in charge Q₁ is closest to: