Question 1

An initially uncharged hollow metallic sphere with radius of 6 cm has a small object with a charge of +14 µC carefully placed at the center of the sphere through a hole in the latter's surface.With the charge in place,what charge is now present on the outside surface of the sphere?​

Accepted Answer

A) zero 
B) −14 µC 
C) +5 600 µC 
D) +14 µC 
E) ​−5 600 µC

Question 2

A Van de Graaff generator has a spherical dome of radius 50.0 cm.Operating in dry air,where "atmospheric breakdown" is at Emax = 3.0 × 106 N/C,what is the maximum charge that can be held on the dome? (ke = 8.99 × 109 N⋅m2/C2)​

Accepted Answer

A) 1.7E-4 C 
B) 8.3E-5 C. 
C) 4.2E-6 C 
D) 8.3E-5 C 
E) ​1.7E-6 C

Question 3

A proton initially moves left to right along the x axis at a speed of 7.0 × 103 m/s.It moves into an electric field,which points in the negative x direction,and travels a distance of 0.70 m before coming to rest.What acceleration magnitude does the proton experience?​

Accepted Answer

A) 7.0E+3 m/s2 
B) 3.5E+7 m/s2 
C) 1.8E+9 m/s2 
D) 1.4E+12 m/s2 
E) 2.5E+9 m/s2

Question 4

Two identical balls have the same amount of charge,but the charge on ball A is positive and the charge on ball B is negative.The balls are placed on a smooth,level,frictionless table whose top is an insulator.Which of the following is true?

Accepted Answer

A) Since the force on A is equal but opposite to the force on B,they will not move. 
B) They will move together with constant acceleration. 
C) Since the force on both balls is negative,they will move in the negative direction. 
D) None of the above is correct.

Question 5

In x-ray machines,electrons are subjected to electric fields as great as 6.0 × 105 N/C.Find an electron's acceleration in this field.(me = 9.11 × 10−31 kg,e = 1.6 × 10−19 C)

Accepted Answer

A) 1.1E+17 m/s2 
B) 3.4E+13 m/s2 
C) 8.7E+10 m/s2 
D) 2.9E+8 m/s2 
E) ​4.1E+13 m/s2

Question 6

Charge A has 10 electric field lines coming out,Charge B has 20 lines coming out,and Charge C has 30 lines coming in.Which pair of these charges will have the largest force between them if placed one cm apart?

Accepted Answer

A) A and B 
B) B and C 
C) C and A 
D) More information is needed.

Question 7

Three equal positive charges are placed on the x-axis,one at the origin,one at x = 4 m,and the third at x = 7 m.Of the following points,which has the greatest magnitude electric field?​

Accepted Answer

A) x = 3 m 
B) x = 5.5 m 
C) x = 8 m 
D) The electric field has the same magnitude at all three positions. 
E) ​x = 0 m

Question 8

The electric field in a cathode ray tube is supposed to accelerate electrons from 0 to 3.2 × 107 m/s in a distance of 2.00 cm.What electric field is required? (me = 9.11 × 10−31 kg and e = 1.60 × 10−19 C)​

Accepted Answer

A) 4.6E+4 N/C 
B) 2.3E+5 N/C 
C) 1.5E+5 N/C 
D) 2.9E+5 N/C 
E) 1.6E+4 N/C

Question 9

The charge per unit length on an insulator is 6.2 μC/m.On a 2.0-m length of this material,what is the difference in the number of electrons and the number of protons?

Accepted Answer

A) There are 7.8 × 1013 more electrons than protons. 
B) There are 7.8 × 1013 more protons than electrons. 
C) There are 3.9 × 1013 more protons than electrons. 
D) There are 3.9 × 1013 more electrons than protons.

Question 10

A 6.6-μC charge is placed at the origin and a second charge is placed on the x-axis at x = 0.1 m.If the resulting force on the second charge is 5.7 N in the positive x-direction,what is the value of its charge?​

Accepted Answer

A) 1.0 μC 
B) 1.0 nC 
C) -1.0 μC 
D) -1.0 nC 
E) ​0 μC

Question 11

The electric field at the surface of a positively charged conductor has a direction characterized by which of the following?

Accepted Answer

A) tangent to the surface 
B) perpendicular inward toward the charge 
C) at a 45° angle to the surface 
D) perpendicular outward and away from the charge

Question 12

Charges q,q,and -q are placed on the x-axis at x = 0,x = 4 m,and x = 6 m,respectively.At which of the following points does the electric field have the greatest magnitude?​

Accepted Answer

A) x = 3 m 
B) x = 5 m 
C) x = 8 m 
D) The electric field has the same magnitude at all three positions. 
E) ​x = 7 m

Question 13

Two point charges are 12 cm apart.They are moved to a new separation of 3 cm.By what factor does the resulting mutual force between them change?

Accepted Answer

A) 1/4 
B) 4 
C) 1/16 
D) 16 
E) ​4.5

Question 14

In the Millikan oil-drop experiment it was found that oil droplets:

Accepted Answer

A) could only have positive net charge. 
B) could only have negative net charge. 
C) could only have negative or zero net charge. 
D) could have positive,negative,or zero net charge.

Question 15

An isolated,charged conductor is in electrostatic equilibrium.Which statement is correct?​

Accepted Answer

A) ​The net charge is never zero inside the conductor. 
B) ​The electric field is always zero just outside the conductor. 
C) ​The charge density on the conductor's surface is greatest where the surface is sharpest. 
D) ​None of these statements are correct.

Question 16

A charge Q accumulates on the hollow metallic dome,of radius R,of a Van de Graaff generator.A probe measures the electric field strength at various points outside the sphere surface.If the probe is initially at a distance 2R from the sphere's center and then is moved to 3R,by what factor will the electric field reading change?

Accepted Answer

A) (3/2)2 
B) 3/2 
C) 2/3 
D) (2/3)2 
E) ​1

Question 17

About how many electrons are in 40 grams of water (H2O)?

Accepted Answer

A) 4E+26 
B) 2E+25 
C) 1E+24 
D) 2E+22 
E) 4E+27

Question 18

How can a charged object attract an uncharged object made of non-conducting material?

Accepted Answer

A) The uncharged object must somehow gain a like charge. 
B) The uncharged object must somehow gain an unlike charge. 
C) The charges in the uncharged object can become polarized. 
D) Attraction of an insulator is not possible.

Question 19

Four charges are at the corners of a square,with B and C on opposite 
Corners.Charges A and D,on the other two corners,have equal charge,while both B and C have a charge of +1.0 C.What is the charge on A so that the force on B is zero?

Accepted Answer

A) −1.0 C 
B) −0.50 C 
C) −0.35 C 
D) −0.71 C

Question 20

Which of the following best characterizes electrical insulators?

Accepted Answer

A) charges on the surface don't move 
B) high tensile strength 
C) electric charges move freely 
D) good heat conductors

Exam 15: Electric Forces and Fields

An initially uncharged hollow metallic sphere with radius of 6 cm has a small object with a charge of +14 µC carefully placed at the center of the sphere through a hole in the latter's surface.With the charge in place,what charge is now present on the outside surface of the sphere?

A Van de Graaff generator has a spherical dome of radius 50.0 cm.Operating in dry air,where "atmospheric breakdown" is at E_max = 3.0 × 10⁶ N/C,what is the maximum charge that can be held on the dome? (k_e = 8.99 × 10⁹ N⋅m²/C²)

A proton initially moves left to right along the x axis at a speed of 7.0 × 10³ m/s.It moves into an electric field,which points in the negative x direction,and travels a distance of 0.70 m before coming to rest.What acceleration magnitude does the proton experience?

Two identical balls have the same amount of charge,but the charge on ball A is positive and the charge on ball B is negative.The balls are placed on a smooth,level,frictionless table whose top is an insulator.Which of the following is true?

In x-ray machines,electrons are subjected to electric fields as great as 6.0 × 10⁵ N/C.Find an electron's acceleration in this field.(m_e = 9.11 × 10−³¹ kg,e = 1.6 × 10−¹⁹ C)

Charge A has 10 electric field lines coming out,Charge B has 20 lines coming out,and Charge C has 30 lines coming in.Which pair of these charges will have the largest force between them if placed one cm apart?

Three equal positive charges are placed on the x-axis,one at the origin,one at x = 4 m,and the third at x = 7 m.Of the following points,which has the greatest magnitude electric field?

The electric field in a cathode ray tube is supposed to accelerate electrons from 0 to 3.2 × 10⁷ m/s in a distance of 2.00 cm.What electric field is required? (m_e = 9.11 × 10−³¹ kg and e = 1.60 × 10−¹⁹ C)

The charge per unit length on an insulator is 6.2 μC/m.On a 2.0-m length of this material,what is the difference in the number of electrons and the number of protons?

A 6.6-μC charge is placed at the origin and a second charge is placed on the x-axis at x = 0.1 m.If the resulting force on the second charge is 5.7 N in the positive x-direction,what is the value of its charge?

The electric field at the surface of a positively charged conductor has a direction characterized by which of the following?

Charges q,q,and -q are placed on the x-axis at x = 0,x = 4 m,and x = 6 m,respectively.At which of the following points does the electric field have the greatest magnitude?

Two point charges are 12 cm apart.They are moved to a new separation of 3 cm.By what factor does the resulting mutual force between them change?

In the Millikan oil-drop experiment it was found that oil droplets:

An isolated,charged conductor is in electrostatic equilibrium.Which statement is correct?

About how many electrons are in 40 grams of water (H₂O) ?

How can a charged object attract an uncharged object made of non-conducting material?

Four charges are at the corners of a square,with B and C on opposite Corners.Charges A and D,on the other two corners,have equal charge,while both B and C have a charge of +1.0 C.What is the charge on A so that the force on B is zero?

Which of the following best characterizes electrical insulators?

Exam 15: Electric Forces and Fields

An initially uncharged hollow metallic sphere with radius of 6 cm has a small object with a charge of +14 µC carefully placed at the center of the sphere through a hole in the latter's surface.With the charge in place,what charge is now present on the outside surface of the sphere?​

A Van de Graaff generator has a spherical dome of radius 50.0 cm.Operating in dry air,where "atmospheric breakdown" is at Emax = 3.0 × 106 N/C,what is the maximum charge that can be held on the dome? (ke = 8.99 × 109 N⋅m2/C2) ​

A proton initially moves left to right along the x axis at a speed of 7.0 × 103 m/s.It moves into an electric field,which points in the negative x direction,and travels a distance of 0.70 m before coming to rest.What acceleration magnitude does the proton experience?​

Two identical balls have the same amount of charge,but the charge on ball A is positive and the charge on ball B is negative.The balls are placed on a smooth,level,frictionless table whose top is an insulator.Which of the following is true?

In x-ray machines,electrons are subjected to electric fields as great as 6.0 × 105 N/C.Find an electron's acceleration in this field.(me = 9.11 × 10−31 kg,e = 1.6 × 10−19 C)

Charge A has 10 electric field lines coming out,Charge B has 20 lines coming out,and Charge C has 30 lines coming in.Which pair of these charges will have the largest force between them if placed one cm apart?

Three equal positive charges are placed on the x-axis,one at the origin,one at x = 4 m,and the third at x = 7 m.Of the following points,which has the greatest magnitude electric field?​

The electric field in a cathode ray tube is supposed to accelerate electrons from 0 to 3.2 × 107 m/s in a distance of 2.00 cm.What electric field is required? (me = 9.11 × 10−31 kg and e = 1.60 × 10−19 C) ​

The charge per unit length on an insulator is 6.2 μC/m.On a 2.0-m length of this material,what is the difference in the number of electrons and the number of protons?

A 6.6-μC charge is placed at the origin and a second charge is placed on the x-axis at x = 0.1 m.If the resulting force on the second charge is 5.7 N in the positive x-direction,what is the value of its charge?​

The electric field at the surface of a positively charged conductor has a direction characterized by which of the following?

Charges q,q,and -q are placed on the x-axis at x = 0,x = 4 m,and x = 6 m,respectively.At which of the following points does the electric field have the greatest magnitude?​

Two point charges are 12 cm apart.They are moved to a new separation of 3 cm.By what factor does the resulting mutual force between them change?

In the Millikan oil-drop experiment it was found that oil droplets:

An isolated,charged conductor is in electrostatic equilibrium.Which statement is correct?​

About how many electrons are in 40 grams of water (H2O) ?

How can a charged object attract an uncharged object made of non-conducting material?

Four charges are at the corners of a square,with B and C on opposite Corners.Charges A and D,on the other two corners,have equal charge,while both B and C have a charge of +1.0 C.What is the charge on A so that the force on B is zero?

Which of the following best characterizes electrical insulators?

An initially uncharged hollow metallic sphere with radius of 6 cm has a small object with a charge of +14 µC carefully placed at the center of the sphere through a hole in the latter's surface.With the charge in place,what charge is now present on the outside surface of the sphere?

A Van de Graaff generator has a spherical dome of radius 50.0 cm.Operating in dry air,where "atmospheric breakdown" is at E_max = 3.0 × 10⁶ N/C,what is the maximum charge that can be held on the dome? (k_e = 8.99 × 10⁹ N⋅m²/C²)

A proton initially moves left to right along the x axis at a speed of 7.0 × 10³ m/s.It moves into an electric field,which points in the negative x direction,and travels a distance of 0.70 m before coming to rest.What acceleration magnitude does the proton experience?

In x-ray machines,electrons are subjected to electric fields as great as 6.0 × 10⁵ N/C.Find an electron's acceleration in this field.(m_e = 9.11 × 10−³¹ kg,e = 1.6 × 10−¹⁹ C)

Three equal positive charges are placed on the x-axis,one at the origin,one at x = 4 m,and the third at x = 7 m.Of the following points,which has the greatest magnitude electric field?

The electric field in a cathode ray tube is supposed to accelerate electrons from 0 to 3.2 × 10⁷ m/s in a distance of 2.00 cm.What electric field is required? (m_e = 9.11 × 10−³¹ kg and e = 1.60 × 10−¹⁹ C)

A 6.6-μC charge is placed at the origin and a second charge is placed on the x-axis at x = 0.1 m.If the resulting force on the second charge is 5.7 N in the positive x-direction,what is the value of its charge?

Charges q,q,and -q are placed on the x-axis at x = 0,x = 4 m,and x = 6 m,respectively.At which of the following points does the electric field have the greatest magnitude?

An isolated,charged conductor is in electrostatic equilibrium.Which statement is correct?

About how many electrons are in 40 grams of water (H₂O) ?