Question 1

Three 2.50 μC charges are placed on tiny conducting spheres at the ends of 1.00 m-long strings that are connected at 120° angles as shown below.The magnitude,in N,of the tension in any one of the strings is

Accepted Answer

Each string has to support the weight of two charges, so the total force on each string is:
F = (2)(kq^2/r^2)sin(60°) 
where k = 9x10^9 Nm^2/C^2, q = 2.50 μC = 2.50x10^-6 C, and r = 1.00 m. 
Plugging in the values gives: 
F = (2)(9x10^9)(2.50x10^-6)^2/(1.00)^2(sin60°) 
F = 3.25x10^-10 N = 3.25x10^-7 N 
So the tension in each string is 3.25x10^-7 N, which is closest to answer choice B.

Question 2

Three 2.50 μC charges are placed on tiny conducting spheres at the ends of 1.00 m-long strings that are connected at 120° angles as shown below.The magnitude,in N,of the force on the knot at the center is

Accepted Answer

The answer of Three 2.50 μC charges are placed on...

Question 3

A positively charged particle is moving in the +y-direction when it enters a region with a uniform electric field pointing in the +x-direction.Which of the diagrams below shows its path while it is in the region where the electric field exists.The region with the field is the region between the plates bounding each figure.The field lines always point to the right.The x-direction is to the right;the y-direction is up.

Accepted Answer

The answer of A positively charged particle is moving in...

Question 4

Two imaginary spherical surfaces of radius R and 2R respectively surround a positive point charge Q located at the center of the concentric spheres.When compared to the number of field lines N₁ going through the sphere of radius R,the number of electric field lines N₂ going through the sphere of radius 2R is

Accepted Answer

The answer of Two imaginary spherical surfaces of radius R...

Question 5

Which one of the diagrams below is not a possible electric field configuration for a region of space which does not contain any charges?

Accepted Answer

Electric field lines must form closed loops or extend to infinity. In option D, one of the field lines terminates at a point which violates this rule.

Question 6

Suppose a uniform electric field of 4 N/C is in the positive x direction.When a charge is placed at and fixed to the origin,the resulting electric field on the x axis at x = 2 m becomes zero.What is the magnitude of the electric field at x = 4 m on the x axis at this time?

Accepted Answer

Since the electric field on the x-axis becomes zero at x = 2 m, there must be another charge creating an electric field that cancels out the initial electric field. This means that the distance between the two charges is 2 m. Using the formula for electric field due to a point charge (E = kq/r^2), we can find that the magnitude of the charge creating the field is q = Er^2/k = (4 N/C) * (2 m)^2 / (9 x 10^9 N*m^2/C^2) = 1.78 x 10^-5 C. Now, we can use this charge to find the electric field at x = 4 m using the same formula: E = kq/(x^2) = (9 x 10^9 N*m^2/C^2) * (1.78 x 10^-5 C) / (4 m)^2 = 2 N/C.

Question 7

The symbol 
Appears in Coulomb's law because we use independently defined units for

Accepted Answer

The answer of The symbol 
Appears in Coulomb's law because...

Question 8

Three pith balls supported by insulating threads hang from a support.We know that ball X is positively charged.When ball X is brought near balls Y and Z without touching them,it attracts Y and repels Z.Since pith is an insulating material,we can conclude that

Accepted Answer

When ball X is positively charged, it induces a negative charge on the side of balls Y and Z closest to it and a positive charge on the far side. This is because the positively charged ball X repels the positive charges in ball Y and attracts the negative charges in ball Z. Therefore, Y is negatively charged or neutral (has no net charge) since it is attracted to the positively charged ball X, while Z is positively charged or neutral (has no net charge) since it is repelled by ball X. Thus, the only option that fits this scenario is E.

Question 9

Three 2.50 μC charges are placed on tiny conducting spheres at the ends of 1.00 m-long strings that are connected at 120° angles as shown below.The magnitude,in N,of the force on any one of the charges is

Accepted Answer

The answer of Three 2.50 μC charges are placed on...

Question 10

Three pith balls supported by insulating threads hang from a support.We know that ball X is positively charged.When ball X is brought near balls Y and Z without touching them,it attracts Y and repels Z.Since pith is an insulating material,we can conclude that

Accepted Answer

The answer of Three pith balls supported by insulating threads...

Question 11

The electron gun in a television tube accelerates electrons (mass = 9.11 × 10−³¹ kg,charge = 1.60 × 10−¹⁹ C)from rest to 3.00 × 10⁷ m/s within a distance of 2.00 cm.What electric field is required?

Accepted Answer

The answer of The electron gun in a television tube...

Question 12

Two charged particles,Q₁ and Q₂,are a distance r apart with Q₂ = 5Q₁.Compare the forces they exert on one another when Is the force Q₂ exerts on Q₁ and Is the force Q₁ exerts on Q₂.

Accepted Answer

The answer of Two charged particles,Q₁ and Q₂,are a distance...

Question 13

Two tiny metal spheres are fixed to the ends of a non-conducting string of length 
)Equal charges,+q,are placed on the metal spheres.Randall says that the force on the string has magnitude 
)Tilden says that the tension in the string has magnitude 
)Which one,if either,is correct?

Accepted Answer

The answer of Two tiny metal spheres are fixed to...

Question 14

A negatively charged particle is moving in the +x-direction when it enters a region with a uniform electric field pointing in the +x-direction.Which graph gives its position as a function of time correctly? (Its initial position is x = 0 at t = 0. )

Accepted Answer

The answer of A negatively charged particle is moving in...

Question 15

Two uniform rods,each of length 2.0 m,are bent to form semicircles.One rod has a charger per unit lent of 1.5 nC/m,and the other has a charge per unit length of -1.5 nC/m.The semicircles are joined to make a circle.What is the magnitude of the electric field at the center of the circle?

Accepted Answer

The answer of Two uniform rods,each of length 2.0 m,are...

Question 16

Rubber rods charged by rubbing with cat fur repel each other.Glass rods charged by rubbing with silk repel each other.A rubber rod and a glass rod charged respectively as above attract each other.A possible explanation is that

Accepted Answer

Rubber rods charged with cat fur become negatively charged, while glass rods charged with silk become positively charged. Therefore, the rubber rod and glass rod charged in this way would have opposite charges, leading to attraction.

Question 17

Two identical pith balls supported by insulating threads hang side by side and close together,as shown below. 
One is positively charged;the other is neutral.We can conclude that

Accepted Answer

As the positively charged pith ball has excess positive charge, this implies it has more protons than electrons. This gives it an electric field that spreads out in all directions. Since the neutral pith ball is nearby, it experiences the electric field and becomes polarized. Electrons are repelled from the neutral ball and they accumulate on the far side of it, away from the positively charged pith ball. This creates an excess of negative charge on the far side of the neutral ball, which attracts positive charge from the positively charged pith ball. Electric field lines emanating from the positively charged pith ball pass through the region occupied by the neutral ball, causing some fraction of these field lines to end on the neutral ball. Therefore, some of the field lines leaving the positively charged pith ball end on the neutral pith ball.

Question 18

In a diagram of charges and electric field lines charge 
Has twelve field lines going outward from it and charge 
Has three field lines going into it.If one of the charges is 100 nC,what is the other one?

Accepted Answer

The answer of In a diagram of charges and electric...

Question 19

Enrico says that positive charge is created when you rub a glass rod with silk,and that negative charge is simply the absence of positive charge.Rosetta says that negative charge is created and that positive charge is the absence of positive charge.(She has heard that Ben Franklin should have reversed the signs he associated with the charges. )Which one,if either,is correct?

Accepted Answer

When a glass rod is rubbed with silk, electrons (which carry negative charge) are transferred from one material to the other. This does not create charge but redistributes it, leaving one object positively charged (due to a deficit of electrons) and the other negatively charged (due to an excess of electrons). Both positive and negative charges are inherent in materials; the process of rubbing merely separates them.

Question 20

When a positive charge q is placed in the field created by two other charges Q₁ and Q₂,each a distance r away from q,the acceleration of q is

Accepted Answer

The acceleration of q will be determined by the vector sum of the electric fields created by Q₁ and Q₂ at the location of q. The electric field created by each charge will exert a force on q, and the net force will determine the acceleration of q. Since the electric fields are vectors, their sum must also be a vector, and the direction of the acceleration will be determined by the direction of the vector sum of the electric fields.

Quiz 23: Electric Fields

Three 2.50 μC charges are placed on tiny conducting spheres at the ends of 1.00 m-long strings that are connected at 120° angles as shown below.The magnitude,in N,of the tension in any one of the strings is

Three 2.50 μC charges are placed on tiny conducting spheres at the ends of 1.00 m-long strings that are connected at 120° angles as shown below.The magnitude,in N,of the force on the knot at the center is

Which one of the diagrams below is not a possible electric field configuration for a region of space which does not contain any charges?

Suppose a uniform electric field of 4 N/C is in the positive x direction.When a charge is placed at and fixed to the origin,the resulting electric field on the x axis at x = 2 m becomes zero.What is the magnitude of the electric field at x = 4 m on the x axis at this time?

The symbol Appears in Coulomb's law because we use independently defined units for

Three pith balls supported by insulating threads hang from a support.We know that ball X is positively charged.When ball X is brought near balls Y and Z without touching them,it attracts Y and repels Z.Since pith is an insulating material,we can conclude that

Three 2.50 μC charges are placed on tiny conducting spheres at the ends of 1.00 m-long strings that are connected at 120° angles as shown below.The magnitude,in N,of the force on any one of the charges is

Three pith balls supported by insulating threads hang from a support.We know that ball X is positively charged.When ball X is brought near balls Y and Z without touching them,it attracts Y and repels Z.Since pith is an insulating material,we can conclude that

The electron gun in a television tube accelerates electrons (mass = 9.11 × 10−³¹ kg,charge = 1.60 × 10−¹⁹ C)from rest to 3.00 × 10⁷ m/s within a distance of 2.00 cm.What electric field is required?

Two charged particles,Q₁ and Q₂,are a distance r apart with Q₂ = 5Q₁.Compare the forces they exert on one another when Is the force Q₂ exerts on Q₁ and Is the force Q₁ exerts on Q₂.

Two tiny metal spheres are fixed to the ends of a non-conducting string of length ) Equal charges,+q,are placed on the metal spheres.Randall says that the force on the string has magnitude ) Tilden says that the tension in the string has magnitude ) Which one,if either,is correct?

A negatively charged particle is moving in the +x-direction when it enters a region with a uniform electric field pointing in the +x-direction.Which graph gives its position as a function of time correctly? (Its initial position is x = 0 at t = 0. )

Two uniform rods,each of length 2.0 m,are bent to form semicircles.One rod has a charger per unit lent of 1.5 nC/m,and the other has a charge per unit length of -1.5 nC/m.The semicircles are joined to make a circle.What is the magnitude of the electric field at the center of the circle?

Rubber rods charged by rubbing with cat fur repel each other.Glass rods charged by rubbing with silk repel each other.A rubber rod and a glass rod charged respectively as above attract each other.A possible explanation is that

Two identical pith balls supported by insulating threads hang side by side and close together,as shown below. One is positively charged;the other is neutral.We can conclude that

In a diagram of charges and electric field lines charge Has twelve field lines going outward from it and charge Has three field lines going into it.If one of the charges is 100 nC,what is the other one?

When a positive charge q is placed in the field created by two other charges Q₁ and Q₂,each a distance r away from q,the acceleration of q is

Quiz 23: Electric Fields

Three 2.50 μC charges are placed on tiny conducting spheres at the ends of 1.00 m-long strings that are connected at 120° angles as shown below.The magnitude,in N,of the tension in any one of the strings is

Three 2.50 μC charges are placed on tiny conducting spheres at the ends of 1.00 m-long strings that are connected at 120° angles as shown below.The magnitude,in N,of the force on the knot at the center is

Which one of the diagrams below is not a possible electric field configuration for a region of space which does not contain any charges?

Suppose a uniform electric field of 4 N/C is in the positive x direction.When a charge is placed at and fixed to the origin,the resulting electric field on the x axis at x = 2 m becomes zero.What is the magnitude of the electric field at x = 4 m on the x axis at this time?

The symbol Appears in Coulomb's law because we use independently defined units for

Three pith balls supported by insulating threads hang from a support.We know that ball X is positively charged.When ball X is brought near balls Y and Z without touching them,it attracts Y and repels Z.Since pith is an insulating material,we can conclude that

Three 2.50 μC charges are placed on tiny conducting spheres at the ends of 1.00 m-long strings that are connected at 120° angles as shown below.The magnitude,in N,of the force on any one of the charges is

Three pith balls supported by insulating threads hang from a support.We know that ball X is positively charged.When ball X is brought near balls Y and Z without touching them,it attracts Y and repels Z.Since pith is an insulating material,we can conclude that

The electron gun in a television tube accelerates electrons (mass = 9.11 × 10−31 kg,charge = 1.60 × 10−19 C)from rest to 3.00 × 107 m/s within a distance of 2.00 cm.What electric field is required?

Two charged particles,Q1 and Q2,are a distance r apart with Q2 = 5Q1.Compare the forces they exert on one another when Is the force Q2 exerts on Q1 and Is the force Q1 exerts on Q2.

Two tiny metal spheres are fixed to the ends of a non-conducting string of length ) Equal charges,+q,are placed on the metal spheres.Randall says that the force on the string has magnitude ) Tilden says that the tension in the string has magnitude ) Which one,if either,is correct?

A negatively charged particle is moving in the +x-direction when it enters a region with a uniform electric field pointing in the +x-direction.Which graph gives its position as a function of time correctly? (Its initial position is x = 0 at t = 0. )

Two uniform rods,each of length 2.0 m,are bent to form semicircles.One rod has a charger per unit lent of 1.5 nC/m,and the other has a charge per unit length of -1.5 nC/m.The semicircles are joined to make a circle.What is the magnitude of the electric field at the center of the circle?

Rubber rods charged by rubbing with cat fur repel each other.Glass rods charged by rubbing with silk repel each other.A rubber rod and a glass rod charged respectively as above attract each other.A possible explanation is that

Two identical pith balls supported by insulating threads hang side by side and close together,as shown below. One is positively charged;the other is neutral.We can conclude that

In a diagram of charges and electric field lines charge Has twelve field lines going outward from it and charge Has three field lines going into it.If one of the charges is 100 nC,what is the other one?

When a positive charge q is placed in the field created by two other charges Q1 and Q2,each a distance r away from q,the acceleration of q is

The electron gun in a television tube accelerates electrons (mass = 9.11 × 10−³¹ kg,charge = 1.60 × 10−¹⁹ C)from rest to 3.00 × 10⁷ m/s within a distance of 2.00 cm.What electric field is required?

Two charged particles,Q₁ and Q₂,are a distance r apart with Q₂ = 5Q₁.Compare the forces they exert on one another when Is the force Q₂ exerts on Q₁ and Is the force Q₁ exerts on Q₂.

When a positive charge q is placed in the field created by two other charges Q₁ and Q₂,each a distance r away from q,the acceleration of q is