Question 1

What does it mean to say something (for example charge) is "quantized"?

Accepted Answer

A "quantized" something comes in basic units and occurs as an integer number of these basic units. For example, isolated objects will be found to have a charge plus or minus ne where n is an integer and e = 1.6 × 10^-19 Coulombs.

Question 2

To be more effective, how should one shape the tip of a lightning rod?

Accepted Answer

A)  sharpened to a point 
B)  flat (cut off perpendicular to the rod axis) 
C)  with a rounded tip (hemispherical) 
A)  sharpened to a point 
B)  flat (cut off perpendicular to the rod axis) 
C)  with a rounded tip (hemispherical) A

Question 3

Electric field lines

Accepted Answer

A)  are closer together the stronger the field. 
B)  start on negative charges and end on positive charges. 
C)  were invented by Isaac Newton. 
D)  were discovered by Franklin. 
E)  are perpendicular to the lines of force. 
A)  are closer together the stronger the field. 
B)  start on negative charges and end on positive charges. 
C)  were invented by Isaac Newton. 
D)  were discovered by Franklin. 
E)  are perpendicular to the lines of force. A

Question 4

The statement that "the number of field lines passing through a surface is proportional to the net charge enclosed" is known as

Accepted Answer

A)  Franklin's Law. 
B)  Coulomb's Law. 
C)  Gauss's Law. 
D)  The Law of Enclosure. 
E)  Faraday's Law. 
A)  Franklin's Law. 
B)  Coulomb's Law. 
C)  Gauss's Law. 
D)  The Law of Enclosure. 
E)  Faraday's Law.

Question 5

The charge carried by one electron is e = -1.6 × 10-19 C. The number of excess electrons necessary to produce a charge of 1.0 C is

Accepted Answer

A)  6.3 × 106. 
B)  1.6 × 1018. 
C)  1.6 × 1019. 
D)  6.3 × 109. 
E)  6.3 × 1018. 
A)  6.3 × 106. 
B)  1.6 × 1018. 
C)  1.6 × 1019. 
D)  6.3 × 109. 
E)  6.3 × 1018.

Question 6

Two volleyballs, each of mass 0.300 kg, are charged by an electrostatic generator. Each is attached to an identical string and suspended from the same point, as shown in Figure 15-6. They repel each other and hang with separation 50.0 cm. The length of the string from the point of support to the center of a ball is 250. cm.
 
 Determine the charge on each ball.

Accepted Answer

The answer of Two volleyballs, each of mass 0.300 kg,...

Question 7

Electric dipoles always consist of two charges that are

Accepted Answer

A)  equal in magnitude; opposite in sign. 
B)  equal in magnitude; both are positive. 
C)  equal in magnitude; both are negative. 
D)  unequal in magnitude; opposite in sign. 
A)  equal in magnitude; opposite in sign. 
B)  equal in magnitude; both are positive. 
C)  equal in magnitude; both are negative. 
D)  unequal in magnitude; opposite in sign.

Question 8

Consider the x-axis with 4.0 μC at x = 1.0 meter and -2.0 μC at the origin. Where should 6.0 μC be placed so that the net force on it is zero?

Accepted Answer

The answer of Consider the x-axis with 4.0 μC at...

Question 9

A point charge of +Q is placed at the center of a square, and a second point charge of -Q is placed at the upper-left corner. It is observed that an electrostatic force of 2 N acts on the positive charge at the center.
  
 What is the magnitude of the force that acts on the center charge if a third charge of -Q is placed at the lower-left corner?

Accepted Answer

A)  2   N 
B)  2/   N 
C)  zero 
D)  4 N 
A)  2   N 
B)  2/   N 
C)  zero 
D)  4 N

Question 10

Which of the following makes an approximate uniform electric field?

Accepted Answer

A)  a metal charged cylinder 
B)  very large, closely separated, parallel oppositely charged plates 
C)  two long parallel, closely separated, oppositely charged lines of charge 
D)  a very long line of positive charge 
A)  a metal charged cylinder 
B)  very large, closely separated, parallel oppositely charged plates 
C)  two long parallel, closely separated, oppositely charged lines of charge 
D)  a very long line of positive charge

Question 11

A quark can have a charge of

Accepted Answer

A)  e/2. 
B)  -1/3 e. 
C)  -3/2 e. 
D)  e/4. 
A)  e/2. 
B)  -1/3 e. 
C)  -3/2 e. 
D)  e/4.

Question 12

Two point charges of + 6.00 $\mu$C and + 9.00 $\mu$C are placed inside a cube of edge length 0.100 m. The net electric flux due to these charges is given by

Accepted Answer

A)  1.69 × 106 Nm2/C 
B)  4.20 × 106 Nm2 /C 
C)  0.450 × 106 Nm2/C 
D)  3.80 × 106 Nm2/C 
E)  0.340 × 106 Nm2/C 
A)  1.69 × 106 Nm2/C 
B)  4.20 × 106 Nm2 /C 
C)  0.450 × 106 Nm2/C 
D)  3.80 × 106 Nm2/C 
E)  0.340 × 106 Nm2/C

Question 13

Consider point charges of +Q and +4Q, which are separated by 3 m. At what point, on a line between the two charges, would it be possible to place a charge of -Q such that the electrostatic force acting on it would be zero?

Accepted Answer

A)  1 m from the +4 charge 
B)  3 m from the +4 charge 
C)  There is no such point possible. 
D)  1 m from the +Q charge 
E)  3/5 m from the +Q charge 
A)  1 m from the +4 charge 
B)  3 m from the +4 charge 
C)  There is no such point possible. 
D)  1 m from the +Q charge 
E)  3/5 m from the +Q charge

Question 14

Two point charges of magnitude + 4.00 $\mu$C and - 6.00 $\mu$C are placed along the x-axis at x = 0 cm and x = 40.0 cm, respectively. Where must a third charge, q, be placed along the x-axis so that it does not experience any net force because of the other two charges?

Accepted Answer

A)  0.200 m 
B)  0.180 m 
C)  - 0.180 m 
D)  - 1.78 m 
E)  1.78 m 
A)  0.200 m 
B)  0.180 m 
C)  - 0.180 m 
D)  - 1.78 m 
E)  1.78 m

Question 15

-Figure 15-5 shows four Gaussian surfaces surrounding a distribution of charges. Which Gaussian surfaces have no electric flux through them?

Accepted Answer

A)  a. 
B)  b. 
C)  b and d. 
D)  b and c. 
E)  c. 
A)  a. 
B)  b. 
C)  b and d. 
D)  b and c. 
E)  c.

Question 16

State the charge-force law.

Accepted Answer

Like charg

Question 17

Two stationary point charges q1 and q2 are shown in Figure 15-4 the sketch along with some electric field lines representing the field between them.
  
What can you deduce from the sketch?

Accepted Answer

A)  q1is negative and q2 is positive; the magnitudes are equal. 
B)  q1and q2 have the same sign; the magnitudes are equal. 
C)  q1is positive and q2 is negative; the magnitude of q1 is greater than the magnitude of q2. 
D)  q1is positive and q2 is negative; the magnitude of q1 is less than the magnitude of q2. 
E)  q1and q2 have the same sign; the magnitude of q1 is greater than the magnitude of q2. 
A)  q1is negative and q2 is positive; the magnitudes are equal. 
B)  q1and q2 have the same sign; the magnitudes are equal. 
C)  q1is positive and q2 is negative; the magnitude of q1 is greater than the magnitude of q2. 
D)  q1is positive and q2 is negative; the magnitude of q1 is less than the magnitude of q2. 
E)  q1and q2 have the same sign; the magnitude of q1 is greater than the magnitude of q2.

Question 18

If a solid metal sphere and a hollow metal sphere of equal diameters are each given the same charge, the electric field (E) midway between the sphere center and the surface is

Accepted Answer

A)  zero for both. 
B)  greater for the solid sphere than for the hollow sphere. 
C)  greater for the hollow sphere than for the solid sphere. 
D)  equal in magnitude for both, but one is opposite in direction from the other. 
A)  zero for both. 
B)  greater for the solid sphere than for the hollow sphere. 
C)  greater for the hollow sphere than for the solid sphere. 
D)  equal in magnitude for both, but one is opposite in direction from the other.

Question 19

Two point charges of magnitudes + 8.00 $\mu$C, and + 10.0 $\mu$C are placed along the x-axis at x = 0 cm and x = 100 cm, respectively. Where must a third charge be placed along the x-axis so that it does not experience any net force because of the other two charges?

Accepted Answer

A)  47.2 cm 
B)  50 cm 
C)  91.2 cm 
D)  9.12 cm 
E)  4.72 cm 
A)  47.2 cm 
B)  50 cm 
C)  91.2 cm 
D)  9.12 cm 
E)  4.72 cm

Question 20

Electrons carry a

Accepted Answer

A)  negative charge. 
B)  variable charge. 
C)  positive charge. 
D)  neutral charge. 
A)  negative charge. 
B)  variable charge. 
C)  positive charge. 
D)  neutral charge.

Exam 15: Electric Charge, Forces, and Fields

What does it mean to say something (for example charge) is "quantized"?

To be more effective, how should one shape the tip of a lightning rod?

Electric field lines

The statement that "the number of field lines passing through a surface is proportional to the net charge enclosed" is known as

The charge carried by one electron is e = -1.6 × 10-19 C. The number of excess electrons necessary to produce a charge of 1.0 C is

Electric dipoles always consist of two charges that are

Consider the x-axis with 4.0 μC at x = 1.0 meter and -2.0 μC at the origin. Where should 6.0 μC be placed so that the net force on it is zero?

Which of the following makes an approximate uniform electric field?

A quark can have a charge of

Two point charges of + 6.00 μ\muμ C and + 9.00 μ\muμ C are placed inside a cube of edge length 0.100 m. The net electric flux due to these charges is given by

Consider point charges of +Q and +4Q, which are separated by 3 m. At what point, on a line between the two charges, would it be possible to place a charge of -Q such that the electrostatic force acting on it would be zero?

Two point charges of magnitude + 4.00 μ\muμ C and - 6.00 μ\muμ C are placed along the x-axis at x = 0 cm and x = 40.0 cm, respectively. Where must a third charge, q, be placed along the x-axis so that it does not experience any net force because of the other two charges?

-Figure 15-5 shows four Gaussian surfaces surrounding a distribution of charges. Which Gaussian surfaces have no electric flux through them?

State the charge-force law.

Two stationary point charges q1 and q2 are shown in Figure 15-4 the sketch along with some electric field lines representing the field between them. What can you deduce from the sketch?

If a solid metal sphere and a hollow metal sphere of equal diameters are each given the same charge, the electric field (E) midway between the sphere center and the surface is

Two point charges of magnitudes + 8.00 μ\muμ C, and + 10.0 μ\muμ C are placed along the x-axis at x = 0 cm and x = 100 cm, respectively. Where must a third charge be placed along the x-axis so that it does not experience any net force because of the other two charges?

Electrons carry a

Measurement and Problem Solving

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Filters

The charge carried by one electron is e = -1.6 × 10^-19 C. The number of excess electrons necessary to produce a charge of 1.0 C is

Two point charges of + 6.00 $\mu$ C and + 9.00 $\mu$ C are placed inside a cube of edge length 0.100 m. The net electric flux due to these charges is given by

Two point charges of magnitude + 4.00 $\mu$ C and - 6.00 $\mu$ C are placed along the x-axis at x = 0 cm and x = 40.0 cm, respectively. Where must a third charge, q, be placed along the x-axis so that it does not experience any net force because of the other two charges?

Two stationary point charges q₁ and q₂ are shown in Figure 15-4 the sketch along with some electric field lines representing the field between them. What can you deduce from the sketch?

Two point charges of magnitudes + 8.00 $\mu$ C, and + 10.0 $\mu$ C are placed along the x-axis at x = 0 cm and x = 100 cm, respectively. Where must a third charge be placed along the x-axis so that it does not experience any net force because of the other two charges?