Question 1

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 C

Question 2

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 E

Question 3

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 A

Question 4

A tiny sphere carrying a charge of 6.5 µC sits in an electric field, at a point where the electric potential is 240 V.What is the sphere's potential energy?

Accepted Answer

A) 2.7 x 10-8 J 
B) 6.5 x 10-6 J 
C) 1.6 x 10-3 J 
D) 240 J 
E) 3.7 x 107 J 
A) 2.7 x 10-8 J 
B) 6.5 x 10-6 J 
C) 1.6 x 10-3 J 
D) 240 J 
E) 3.7 x 107 J

Question 5

If the electric field is in the positive x direction and has a magnitude given by E = Cx2, where C is a constant, then the electric potential is given by V =

Accepted Answer

A) 2Cx 
B) -2Cx 
C) Cx3/3 
D) -Cx3/3 
E) -3Cx3 
A) 2Cx 
B) -2Cx 
C) Cx3/3 
D) -Cx3/3 
E) -3Cx3

Question 6

The fact that we can define electric potential energy means that:

Accepted Answer

A) the electric force is nonconservative 
B) the electric force is conservative 
C) the work done on a charged particle depends on the path it takes 
D) there is a point where the electric potential energy is exactly zero 
E) it takes work for the electric force to move from some point a to some other point b and back again 
A) the electric force is nonconservative 
B) the electric force is conservative 
C) the work done on a charged particle depends on the path it takes 
D) there is a point where the electric potential energy is exactly zero 
E) it takes work for the electric force to move from some point a to some other point b and back again

Question 7

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 8

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 9

The equipotential surfaces associated with a charged point particle are:

Accepted Answer

A) radially outward from the particle 
B) vertical planes 
C) horizontal planes 
D) concentric spheres centered at the particle 
E) concentric cylinders with the particle on the axis 
A) radially outward from the particle 
B) vertical planes 
C) horizontal planes 
D) concentric spheres centered at the particle 
E) concentric cylinders with the particle on the axis

Question 10

Eight identical spherical raindrops are each at a potential V, relative to the potential far away.They coalesce to make one spherical raindrop whose potential is:

Accepted Answer

A) V/8 
B) V/2 
C) 2V 
D) 4V 
E) 8V 
A) V/8 
B) V/2 
C) 2V 
D) 4V 
E) 8V

Question 11

Two conducting spheres are far apart.The smaller sphere carries a total charge of Q.The larger sphere has a radius that is twice that of the smaller and is neutral.After the two spheres are connected by a conducting wire, the charges on the smaller and larger spheres, respectively, are:

Accepted Answer

A) Q/2 and Q/2 
B) Q/3 and 2Q/3 
C) 2Q/3 and Q/3 
D) 0 and Q 
E) 2Q and -Q 
A) Q/2 and Q/2 
B) Q/3 and 2Q/3 
C) 2Q/3 and Q/3 
D) 0 and Q 
E) 2Q and -Q

Question 12

The potential difference between the ends of a 2-meter stick that is parallel to a uniform electric field is 400 V.The magnitude of the electric field is:

Accepted Answer

A) 0 V/m 
B) 100 V/m 
C) 200 V/m 
D) 400 V/m 
E) 800 V/m 
A) 0 V/m 
B) 100 V/m 
C) 200 V/m 
D) 400 V/m 
E) 800 V/m

Question 13

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 14

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 15

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 16

Choose the correct statement:

Accepted Answer

A) A proton tends to go from a region of low potential to a region of high potential 
B) The potential of a negatively charged conductor must be negative 
C) If   = 0 at a point P then V must be zero at P 
D) If V = 0 at a point P then   must be zero at P 
E) None of the above is correct 
A) A proton tends to go from a region of low potential to a region of high potential 
B) The potential of a negatively charged conductor must be negative 
C) If   = 0 at a point P then V must be zero at P 
D) If V = 0 at a point P then   must be zero at P 
E) None of the above is correct

Question 17

The electric field in a region around the origin is given by   , where C is a constant.The equipotential surfaces are:

Accepted Answer

A) concentric cylinders with axes along the z axis 
B) concentric cylinders with axes along the x axis 
C) concentric spheres centered at the origin 
D) planes parallel to the xy plane 
E) planes parallel to the yz plane 
A) concentric cylinders with axes along the z axis 
B) concentric cylinders with axes along the x axis 
C) concentric spheres centered at the origin 
D) planes parallel to the xy plane 
E) planes parallel to the yz plane

Question 18

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 19

A conducting sphere has charge Q and its electric potential is V, relative to the potential far away.If the charge is doubled to 2Q, the potential is:

Accepted Answer

A) V 
B) 2V 
C) 4V 
D) V/2 
E) V/4 
A) V 
B) 2V 
C) 4V 
D) V/2 
E) V/4

Question 20

A particle with a charge of 5.5 *10-6 C is 3.5 cm from a particle with a charge of -2.3 *10-8 C.The potential energy of this two-particle system, relative to the potential energy at infinite separation, is:

Accepted Answer

A) 3.3 * 10-2 J 
B) -3.3 * 10-2 J 
C) 9.3 * 10-1 J 
D) -9.3 * 10-1 J 
E) 0 J 
A) 3.3 * 10-2 J 
B) -3.3 * 10-2 J 
C) 9.3 * 10-1 J 
D) -9.3 * 10-1 J 
E) 0 J

Exam 24: Electric Potential

An electron volt is:

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

A tiny sphere carrying a charge of 6.5 µC sits in an electric field, at a point where the electric potential is 240 V.What is the sphere's potential energy?

If the electric field is in the positive x direction and has a magnitude given by E = Cx2, where C is a constant, then the electric potential is given by V =

The fact that we can define electric potential energy means that:

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 equipotential surfaces associated with a charged point particle are:

Eight identical spherical raindrops are each at a potential V, relative to the potential far away.They coalesce to make one spherical raindrop whose potential is:

Two conducting spheres are far apart.The smaller sphere carries a total charge of Q.The larger sphere has a radius that is twice that of the smaller and is neutral.After the two spheres are connected by a conducting wire, the charges on the smaller and larger spheres, respectively, are:

The potential difference between the ends of a 2-meter stick that is parallel to a uniform electric field is 400 V.The magnitude of the electric field is:

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?

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:

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

Choose the correct statement:

The electric field in a region around the origin is given by , where C is a constant.The equipotential surfaces are:

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 conducting sphere has charge Q and its electric potential is V, relative to the potential far away.If the charge is doubled to 2Q, the potential is:

A particle with a charge of 5.5 *10-6 C is 3.5 cm from a particle with a charge of -2.3 *10-8 C.The potential energy of this two-particle system, relative to the potential energy at infinite separation, is:

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If the electric field is in the positive x direction and has a magnitude given by E = Cx², where C is a constant, then the electric potential is given by 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?

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 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 particle with a charge of 5.5 10^-6 C is 3.5 cm from a particle with a charge of -2.3 10^-8 C.The potential energy of this two-particle system, relative to the potential energy at infinite separation, is: