Question 1

A wire carrying a charge density of λ C/m is bent into a circle of radius r.What is the electric potential at the center of the circle?

Accepted Answer

A) λ/4πε0r 
B) λ/4πε0 
C) λ/4ε0 
D) λ/2ε0 
E) λ/ε0 
A) λ/4πε0r 
B) λ/4πε0 
C) λ/4ε0 
D) λ/2ε0 
E) λ/ε0

Question 2

Two identical particles, each with charge q, are placed on the x axis, one at the origin and the other at x = 5 cm.A third particle, with charge -q, is placed on the x axis so the potential energy of the three-particle system is the same as the potential energy when they are all infinitely far apart.Its x coordinate is:

Accepted Answer

A) 13 cm 
B) 2.5 cm 
C) 7.5 cm 
D) 10 cm 
E) -5 cm 
A) 13 cm 
B) 2.5 cm 
C) 7.5 cm 
D) 10 cm 
E) -5 cm

Question 3

The electric potential at a certain point is given by V = -7.5x2 + 3x, where V is in volts and x is in meters.What is the electric field at that point?

Accepted Answer

A) = (15x - 3) 
B) = (-15x + 3) 
C) = (-2.5x3 + 1.5 x2) 
D) = (2.5x3 - 1.5 x2) 
E) = 0 
A) = (15x - 3) 
B) = (-15x + 3) 
C) = (-2.5x3 + 1.5 x2) 
D) = (2.5x3 - 1.5 x2) 
E) = 0

Question 4

In separate experiments, four different particles each start from far away with the same speed and impinge directly on a gold nucleus.The masses and charges of the particles are   Rank the particles according to the distance of closest approach to the gold nucleus, from smallest to largest.

Accepted Answer

A) 1, 2, 3, 4 
B) 4, 3, 2, 1 
C) 3, then 1 and 2 tie, then 4 
D) 4, then 1 and 2 tie, then 3 
E) 1 and 2 tie, then 3, then 4 
A) 1, 2, 3, 4 
B) 4, 3, 2, 1 
C) 3, then 1 and 2 tie, then 4 
D) 4, then 1 and 2 tie, then 3 
E) 1 and 2 tie, then 3, then 4

Question 5

In a certain region of space the electric potential increases uniformly from east to west and does not vary in any other direction.The electric field:

Accepted Answer

A) points east and varies with position 
B) points east and does not vary with position 
C) points west and varies with position 
D) points west and does not vary with position 
E) points north and does not vary with position 
A) points east and varies with position 
B) points east and does not vary with position 
C) points west and varies with position 
D) points west and does not vary with position 
E) points north and does not vary with position

Question 6

An electron volt is:

Accepted Answer

A) the force acting on an electron in a field of 1 N/C 
B) the force required to move an electron 1 meter 
C) the energy gained by an electron in moving through a potential difference of 1 volt 
D) the energy needed to move an electron through 1 meter in any electric field 
E) the work done when 1 coulomb of charge is moved through a potential difference of 1 volt 
A) the force acting on an electron in a field of 1 N/C 
B) the force required to move an electron 1 meter 
C) the energy gained by an electron in moving through a potential difference of 1 volt 
D) the energy needed to move an electron through 1 meter in any electric field 
E) the work done when 1 coulomb of charge is moved through a potential difference of 1 volt

Question 7

A total charge of 7 *10-8 C is uniformly distributed throughout a non-conducting sphere with a radius of 5 cm.The electric potential at the surface, relative to the potential far away, is about:

Accepted Answer

A) -1.3 *104 V 
B) 1.3 *104 V 
C) 630 V 
D) 130 V 
E) 0 V 
A) -1.3 *104 V 
B) 1.3 *104 V 
C) 630 V 
D) 130 V 
E) 0 V

Question 8

A particle with charge q is to be brought from far away to a point near an electric dipole.No work is done if the final position of the particle is on:

Accepted Answer

A) the line through the charges of the dipole 
B) a line that is perpendicular to the dipole moment 
C) a line that makes an angle of 45$\degree$ with the dipole moment 
D) a line that makes an angle of 30$\degree$ with the dipole moment 
E) none of the above 
A) the line through the charges of the dipole 
B) a line that is perpendicular to the dipole moment 
C) a line that makes an angle of 45$\degree$ with the dipole moment 
D) a line that makes an angle of 30$\degree$ with the dipole moment 
E) none of the above

Question 9

The Earth's electric field creates a potential that increases 100 V for every meter of altitude.If an object of charge +4.5 mC and mass 68 g falls a distance of 1.0 m from rest under the influence of the Earth's electric and gravitational fields, what is its final kinetic energy?

Accepted Answer

A) 0.22 J 
B) 0.45 J 
C) 0.67 J 
D) 1.1 J 
E) 7.2 J 
A) 0.22 J 
B) 0.45 J 
C) 0.67 J 
D) 1.1 J 
E) 7.2 J

Question 10

An electric dipole consists of two equal and opposite charged particles of mass 1.2 g and charge 3.7 µC separated by 1.7 mm.What is the escape speed of the positive charge - that is, how much speed would you have to give it so it would escape the other charge?

Accepted Answer

A) 200 m/s 
B) 350 m/s 
C) 6600 m/s 
D) 7.1 x 104 m/s 
E) 2.0 x 105 m/s 
A) 200 m/s 
B) 350 m/s 
C) 6600 m/s 
D) 7.1 x 104 m/s 
E) 2.0 x 105 m/s

Question 11

The electric potential in a certain region of space is given by V = -7.5x2 + 3x, where V is in volts and x is in meters.In this region the equipotential surfaces are:

Accepted Answer

A) planes parallel to the x axis 
B) planes parallel to the yz plane 
C) concentric spheres centered at the origin 
D) concentric cylinders with the x axis as the cylinder axis 
E) unknown unless the charge is given 
A) planes parallel to the x axis 
B) planes parallel to the yz plane 
C) concentric spheres centered at the origin 
D) concentric cylinders with the x axis as the cylinder axis 
E) unknown unless the charge is given

Question 12

Two conducting spheres, one having twice the diameter of the other, are separated by a distance large compared to their diameters.The smaller sphere (1)has charge q and the larger sphere (2)is uncharged.If the spheres are connected by a long thin wire and come to equilibrium:

Accepted Answer

A) 1 and 2 have the same potential 
B) 2 has twice the potential of 1 
C) 2 has half the potential of 1 
D) 1 and 2 have the same charge 
E) all of the charge is dissipated 
A) 1 and 2 have the same potential 
B) 2 has twice the potential of 1 
C) 2 has half the potential of 1 
D) 1 and 2 have the same charge 
E) all of the charge is dissipated

Question 13

The graph shows the electric potential as a function of x in a certain region.What is the x component of the electric field in this region if Vs = 50 V?

Accepted Answer

A) 250 V/m 
B) 40 V/m 
C) 10 V/m 
D) -40 V/m 
E) -250 V/m 
A) 250 V/m 
B) 40 V/m 
C) 10 V/m 
D) -40 V/m 
E) -250 V/m

Question 14

An electrically charged object creates an electric field.The electric potential due to this object:

Accepted Answer

A) is a vector that points either towards or away from the object, depending on the sign of the charge 
B) is a vector that makes circular paths around the object 
C) is a non-negative scalar 
D) is a scalar but will be positive or negative depending on the sign of the charge 
E) points in the same direction as the field 
A) is a vector that points either towards or away from the object, depending on the sign of the charge 
B) is a vector that makes circular paths around the object 
C) is a non-negative scalar 
D) is a scalar but will be positive or negative depending on the sign of the charge 
E) points in the same direction as the field

Question 15

The graph shows the electric field as a function of position in a particular region of space.If Exs = 100 N/C, what is the potential difference between x = 3 m and x = 6 m?

Accepted Answer

A) 250 V 
B) 50 V 
C) 0 V 
D) -50 V 
E) -250 V 
A) 250 V 
B) 50 V 
C) 0 V 
D) -50 V 
E) -250 V

Question 16

A particle with a charge of 5.5 *10-8C is fixed at the origin.A particle with a charge of -2.3 * 10-8C is moved from x = 3.5 cm on the x axis to y = 4.3 cm on the y axis.The change in potential energy of the two-particle system is:

Accepted Answer

A) 3.1 * 10-3 J 
B) -3.1 * 10-3 J 
C) 6.0 * 10-5 J 
D) -6.0 * 10-5 J 
E) 0 J 
A) 3.1 * 10-3 J 
B) -3.1 * 10-3 J 
C) 6.0 * 10-5 J 
D) -6.0 * 10-5 J 
E) 0 J

Question 17

A hollow metal sphere is charged to a potential V.The potential at its center is:

Accepted Answer

A) "V" 
B) "0" 
C) "-V" 
D) "2V" 
E) " $\pi$V" 
A) "V" 
B) "0" 
C) "-V" 
D) "2V" 
E) " $\pi$V"

Question 18

A 5-cm radius conducting sphere has a charge density of 2 * 10-6 C/m2 on its surface.Its electric potential, relative to the potential far away, is:

Accepted Answer

A) 1.1 *104 V 
B) 2.2 * 104 V 
C) 2.3 * 105 V 
D) 3.6 * 105 V 
E) 7.2 *106 V 
A) 1.1 *104 V 
B) 2.2 * 104 V 
C) 2.3 * 105 V 
D) 3.6 * 105 V 
E) 7.2 *106 V

Question 19

Three possible configurations for an electron e and a proton p are shown below.Take the zero of potential to be at infinity and rank the three configurations according to the potential at S, from most negative to most positive.

Accepted Answer

A) 1, 2, 3 
B) 3, 2, 1 
C) 2, 3, 1 
D) 1 and 2 tie, then 3 
E) 1 and 3 tie, then 2 
A) 1, 2, 3 
B) 3, 2, 1 
C) 2, 3, 1 
D) 1 and 2 tie, then 3 
E) 1 and 3 tie, then 2

Question 20

Protons in the LHC accelerator in Geneva, Switzerland are accelerated to an energy of 4.0 TeV.What is this in joules?

Accepted Answer

A) 6.4 x 10-19 J 
B) 6.4 x 10-16 J 
C) 6.4 x 10-13 J 
D) 6.4 x 10-10 J 
E) 6.4 x 10-7 J 
A) 6.4 x 10-19 J 
B) 6.4 x 10-16 J 
C) 6.4 x 10-13 J 
D) 6.4 x 10-10 J 
E) 6.4 x 10-7 J

Exam 24: Electric Potential

A wire carrying a charge density of λ C/m is bent into a circle of radius r.What is the electric potential at the center of the circle?

The electric potential at a certain point is given by V = -7.5x2 + 3x, where V is in volts and x is in meters.What is the electric field at that point?

In separate experiments, four different particles each start from far away with the same speed and impinge directly on a gold nucleus.The masses and charges of the particles are Rank the particles according to the distance of closest approach to the gold nucleus, from smallest to largest.

In a certain region of space the electric potential increases uniformly from east to west and does not vary in any other direction.The electric field:

An electron volt is:

A total charge of 7 *10-8 C is uniformly distributed throughout a non-conducting sphere with a radius of 5 cm.The electric potential at the surface, relative to the potential far away, is about:

A particle with charge q is to be brought from far away to a point near an electric dipole.No work is done if the final position of the particle is on:

The Earth's electric field creates a potential that increases 100 V for every meter of altitude.If an object of charge +4.5 mC and mass 68 g falls a distance of 1.0 m from rest under the influence of the Earth's electric and gravitational fields, what is its final kinetic energy?

An electric dipole consists of two equal and opposite charged particles of mass 1.2 g and charge 3.7 µC separated by 1.7 mm.What is the escape speed of the positive charge - that is, how much speed would you have to give it so it would escape the other charge?

The electric potential in a certain region of space is given by V = -7.5x2 + 3x, where V is in volts and x is in meters.In this region the equipotential surfaces are:

Two conducting spheres, one having twice the diameter of the other, are separated by a distance large compared to their diameters.The smaller sphere (1)has charge q and the larger sphere (2)is uncharged.If the spheres are connected by a long thin wire and come to equilibrium:

The graph shows the electric potential as a function of x in a certain region.What is the x component of the electric field in this region if Vs = 50 V?

An electrically charged object creates an electric field.The electric potential due to this object:

The graph shows the electric field as a function of position in a particular region of space.If Exs = 100 N/C, what is the potential difference between x = 3 m and x = 6 m?

A particle with a charge of 5.5 *10-8C is fixed at the origin.A particle with a charge of -2.3 * 10-8C is moved from x = 3.5 cm on the x axis to y = 4.3 cm on the y axis.The change in potential energy of the two-particle system is:

A hollow metal sphere is charged to a potential V.The potential at its center is:

A 5-cm radius conducting sphere has a charge density of 2 * 10-6 C/m2 on its surface.Its electric potential, relative to the potential far away, is:

Three possible configurations for an electron e and a proton p are shown below.Take the zero of potential to be at infinity and rank the three configurations according to the potential at S, from most negative to most positive.

Protons in the LHC accelerator in Geneva, Switzerland are accelerated to an energy of 4.0 TeV.What is this in joules?

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The electric potential at a certain point is given by V = -7.5x² + 3x, where V is in volts and x is in meters.What is the electric field at that point?

A total charge of 7 *10^-8 C is uniformly distributed throughout a non-conducting sphere with a radius of 5 cm.The electric potential at the surface, relative to the potential far away, is about:

The electric potential in a certain region of space is given by V = -7.5x² + 3x, where V is in volts and x is in meters.In this region the equipotential surfaces are:

The graph shows the electric potential as a function of x in a certain region.What is the x component of the electric field in this region if V_s = 50 V?

The graph shows the electric field as a function of position in a particular region of space.If E_xs = 100 N/C, what is the potential difference between x = 3 m and x = 6 m?

A particle with a charge of 5.5 10^-8C is fixed at the origin.A particle with a charge of -2.3 10^-8C is moved from x = 3.5 cm on the x axis to y = 4.3 cm on the y axis.The change in potential energy of the two-particle system is:

A 5-cm radius conducting sphere has a charge density of 2 * 10^-6 C/m² on its surface.Its electric potential, relative to the potential far away, is: