Physics 1260 Final Exam Conceptual Review with
Questions and 100% Correct Answers Chapter 17-
30
Chapter 17: The Electric Field
Two charges that are separated by one meter exert 1-N forces on each other. If
the magnitude of each charge is doubled, the force on each charge is A) 1 N. B) 2
N. C) 4 N. D) 8 N. E) [none of
these] - Answer C) 4 N.
Explanation — Via fe = kq1q2/r^2 , if q1 → 2q1 and q2 → 2q2, then clearly
a factor of 4 appears.
Chapter 17: The Electric Field
, Two charged particles attract each other with a force . If the charges of both
particles are doubled, and the distance between them is also doubled, then the
force of attraction will be A) F. B) 2F. C) F/2. D) F/4. E) [none of these] - Answer A)
F.
Explanation — Via fe = kq1q2/r^2 , if q1 → 2q1 and q2 → 2q2, and (2r)^2=
4r^2 then a factor of 4 cancels.
Chapter 18: Electric Potential
An electron is pushed into an electric field where it acquires a 1 V electrical
potential. If two electrons are pushed the same distance into the same electric
field, the electrical potential of the two electrons is A) 0.25 V. B) 0.5 V. C) 1 V. D)
2 V. E) 4 V. - Answer C) 1 V.
Explanation — Keep in mind that electric potential is primarily about the response
of a test charge to an electric field, and its close association with potential energy
(hence the name). So, same test charge, same response. How much potential
energy is stored in the field? A single electronvolt (1 eV)!
Chapter 18: Electric Potential
Assume that 10 J of work is required to push a charge (initially at rest) into an
electric field. If the charge is then released, it flies back to its starting position with
a kinetic energy of A) zero. B) 5 J. C) 10 J. D) more than 10 J. E) [need more
information] - Answer C) 10 J
Explanation — The charge will experience an electric force F = qE. This force is
compounded over a distance d to give an amount of work done, W = Fd. The
charge has a potential at this point in the form of 10 J of stored (potential) energy.
Via conservation of energy, this stored energy is converted to energy of
movement—kinetic energy—when released.
Questions and 100% Correct Answers Chapter 17-
30
Chapter 17: The Electric Field
Two charges that are separated by one meter exert 1-N forces on each other. If
the magnitude of each charge is doubled, the force on each charge is A) 1 N. B) 2
N. C) 4 N. D) 8 N. E) [none of
these] - Answer C) 4 N.
Explanation — Via fe = kq1q2/r^2 , if q1 → 2q1 and q2 → 2q2, then clearly
a factor of 4 appears.
Chapter 17: The Electric Field
, Two charged particles attract each other with a force . If the charges of both
particles are doubled, and the distance between them is also doubled, then the
force of attraction will be A) F. B) 2F. C) F/2. D) F/4. E) [none of these] - Answer A)
F.
Explanation — Via fe = kq1q2/r^2 , if q1 → 2q1 and q2 → 2q2, and (2r)^2=
4r^2 then a factor of 4 cancels.
Chapter 18: Electric Potential
An electron is pushed into an electric field where it acquires a 1 V electrical
potential. If two electrons are pushed the same distance into the same electric
field, the electrical potential of the two electrons is A) 0.25 V. B) 0.5 V. C) 1 V. D)
2 V. E) 4 V. - Answer C) 1 V.
Explanation — Keep in mind that electric potential is primarily about the response
of a test charge to an electric field, and its close association with potential energy
(hence the name). So, same test charge, same response. How much potential
energy is stored in the field? A single electronvolt (1 eV)!
Chapter 18: Electric Potential
Assume that 10 J of work is required to push a charge (initially at rest) into an
electric field. If the charge is then released, it flies back to its starting position with
a kinetic energy of A) zero. B) 5 J. C) 10 J. D) more than 10 J. E) [need more
information] - Answer C) 10 J
Explanation — The charge will experience an electric force F = qE. This force is
compounded over a distance d to give an amount of work done, W = Fd. The
charge has a potential at this point in the form of 10 J of stored (potential) energy.
Via conservation of energy, this stored energy is converted to energy of
movement—kinetic energy—when released.
