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PHYS 112 FINAL EXAM 2026/2027 – ELECTRICITY,
MAGNETISM, OPTICS & MODERN PHYSICS COMPLETE
(140) CURRENT TESTING QUESTIONS AND CORRECT
ANSWERS WITH DETAILED RATIONALES.
PHYS
Prepare effectively for the PHYS 112 Final Exam with this focused study resource. It
supports review of essential physics concepts, principles, problem-solving methods,
formulas, and key topics relevant to course examination preparation. Use the material
to reinforce your understanding, review important areas, and identify topics that may
require additional study. This resource is suited for physics students, PHYS 112
learners, and candidates preparing for their final physics examination.
MULTIPLE CHOICE.
Section 1: Electrostatics – Charge, Force, and Field (Questions 1–30)
1. A neutral metal sphere is brought near a positively charged rod without
touching it. Which of the following best describes what happens to the
sphere?
A) It becomes negatively charged overall.
B) It becomes positively charged overall.
C) It remains neutral, but charges are redistributed.
D) It repels the rod because like charges repel.
Answer: C
Rationale: When a charged rod is brought near a neutral conductor, the
free electrons in the conductor are attracted or repelled, causing a
separation of charge (induction). The sphere as a whole remains neutral,
but one side becomes positive and the other negative.
2. Two point charges, +3 μC and –5 μC, are separated by a distance of 2
meters. The magnitude of the electrostatic force between them is
approximately:
A) 0.034 N (attractive)
B) 0.034 N (repulsive)
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C) 0.067 N (attractive)
D) 0.067 N (repulsive)
Answer: A
Rationale: Coulomb's Law: F = k|q₁q₂|/r² = (8.99×10⁹)(3×10⁻⁶)(5×10⁻⁶)/2² =
0.0337 N. Opposite charges attract.
3. The electric field inside a perfect conductor in electrostatic equilibrium
is:
A) Zero
B) Maximum at the center
C) Dependent on the applied voltage
D) Uniform throughout
Answer: A
Rationale: In electrostatic equilibrium, the electric field inside a
conductor is zero. Any excess charge resides on the surface, and the field
is perpendicular to the surface.
4. Which statement best explains the difference between conductors and
insulators?
A) Conductors have more protons than insulators.
B) Conductors allow charges to move freely; insulators do not.
C) Insulators have a higher density than conductors.
D) Conductors are always metals.
Answer: B
Rationale: The key difference is the mobility of charges. Conductors have
free electrons that can move easily; insulators hold their electrons tightly.
5. An electron is placed in a uniform electric field directed to the right. The
electron will accelerate:
A) To the right
B) To the left
C) Upward
D) It will remain stationary
Answer: B
Rationale: The force on a charge in an electric field is F = qE. An electron
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has a negative charge, so it experiences a force opposite the direction of
the field. Thus, it accelerates to the left.
6. What is the electric potential energy of two charges, +2 μC and -4 μC,
separated by 0.5 meters?
A) +0.144 J
B) -0.144 J
C) +0.072 J
D) -0.072 J
Answer: B
Rationale: U = kq₁q₂/r = (8.99×10⁹)(2×10⁻⁶)(-4×10⁻⁶)/0.5 = -0.144 J. Opposite
charges have negative potential energy.
7. Equipotential surfaces are always __________ to electric field lines.
A) Parallel
B) Perpendicular
C) At a 45° angle
D) Identical
Answer: B
Rationale: Equipotential surfaces are surfaces of constant electric
potential. No work is done moving a charge along an equipotential, so the
electric field (which does work) must be perpendicular to the surface.
8. A charge of 5 C moves through a potential difference of 10 V. The change
in electric potential energy is:
A) 2 J
B) 5 J
C) 10 J
D) 50 J
Answer: D
Rationale: ΔU = qΔV = (5 C)(10 V) = 50 J.
9. Which of the following is true regarding electric field lines?
A) They point from negative to positive charges.
B) They are closer together where the field is weaker.
C) They can cross each other.
D) They point from positive to negative charges.
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Answer: D
Rationale: Electric field lines originate on positive charges and terminate
on negative charges. They never cross, and density indicates field
strength.
10. A dipole consists of a +q and –q charge separated by a distance d. The
dipole moment p is:
A) qd
B) q/d
C) d/q
D) q²d
Answer: A
Rationale: The electric dipole moment is defined as the magnitude of the
charge times the separation distance: p = qd.
11. Gauss's Law relates the electric flux through a closed surface to:
A) The total charge enclosed by the surface
B) The electric field on the surface
C) The potential difference across the surface
D) The magnetic field inside the surface
Answer: A
Rationale: Gauss's Law states that the net electric flux through any closed
surface is equal to the total enclosed charge divided by ε₀.
12. A point charge is placed at the center of a spherical Gaussian surface.
If the radius of the sphere is doubled, the electric flux through the
surface:
A) Doubles
B) Quadruples
C) Halves
D) Remains the same
Answer: D
Rationale: Gauss's Law states that flux depends only on the enclosed
charge, not the size or shape of the Gaussian surface.
13. Two charges, +Q and +2Q, are separated by a distance d. At what point
on the line connecting them is the electric field zero?
PHYS 112 FINAL EXAM 2026/2027 – ELECTRICITY,
MAGNETISM, OPTICS & MODERN PHYSICS COMPLETE
(140) CURRENT TESTING QUESTIONS AND CORRECT
ANSWERS WITH DETAILED RATIONALES.
PHYS
Prepare effectively for the PHYS 112 Final Exam with this focused study resource. It
supports review of essential physics concepts, principles, problem-solving methods,
formulas, and key topics relevant to course examination preparation. Use the material
to reinforce your understanding, review important areas, and identify topics that may
require additional study. This resource is suited for physics students, PHYS 112
learners, and candidates preparing for their final physics examination.
MULTIPLE CHOICE.
Section 1: Electrostatics – Charge, Force, and Field (Questions 1–30)
1. A neutral metal sphere is brought near a positively charged rod without
touching it. Which of the following best describes what happens to the
sphere?
A) It becomes negatively charged overall.
B) It becomes positively charged overall.
C) It remains neutral, but charges are redistributed.
D) It repels the rod because like charges repel.
Answer: C
Rationale: When a charged rod is brought near a neutral conductor, the
free electrons in the conductor are attracted or repelled, causing a
separation of charge (induction). The sphere as a whole remains neutral,
but one side becomes positive and the other negative.
2. Two point charges, +3 μC and –5 μC, are separated by a distance of 2
meters. The magnitude of the electrostatic force between them is
approximately:
A) 0.034 N (attractive)
B) 0.034 N (repulsive)
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C) 0.067 N (attractive)
D) 0.067 N (repulsive)
Answer: A
Rationale: Coulomb's Law: F = k|q₁q₂|/r² = (8.99×10⁹)(3×10⁻⁶)(5×10⁻⁶)/2² =
0.0337 N. Opposite charges attract.
3. The electric field inside a perfect conductor in electrostatic equilibrium
is:
A) Zero
B) Maximum at the center
C) Dependent on the applied voltage
D) Uniform throughout
Answer: A
Rationale: In electrostatic equilibrium, the electric field inside a
conductor is zero. Any excess charge resides on the surface, and the field
is perpendicular to the surface.
4. Which statement best explains the difference between conductors and
insulators?
A) Conductors have more protons than insulators.
B) Conductors allow charges to move freely; insulators do not.
C) Insulators have a higher density than conductors.
D) Conductors are always metals.
Answer: B
Rationale: The key difference is the mobility of charges. Conductors have
free electrons that can move easily; insulators hold their electrons tightly.
5. An electron is placed in a uniform electric field directed to the right. The
electron will accelerate:
A) To the right
B) To the left
C) Upward
D) It will remain stationary
Answer: B
Rationale: The force on a charge in an electric field is F = qE. An electron
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has a negative charge, so it experiences a force opposite the direction of
the field. Thus, it accelerates to the left.
6. What is the electric potential energy of two charges, +2 μC and -4 μC,
separated by 0.5 meters?
A) +0.144 J
B) -0.144 J
C) +0.072 J
D) -0.072 J
Answer: B
Rationale: U = kq₁q₂/r = (8.99×10⁹)(2×10⁻⁶)(-4×10⁻⁶)/0.5 = -0.144 J. Opposite
charges have negative potential energy.
7. Equipotential surfaces are always __________ to electric field lines.
A) Parallel
B) Perpendicular
C) At a 45° angle
D) Identical
Answer: B
Rationale: Equipotential surfaces are surfaces of constant electric
potential. No work is done moving a charge along an equipotential, so the
electric field (which does work) must be perpendicular to the surface.
8. A charge of 5 C moves through a potential difference of 10 V. The change
in electric potential energy is:
A) 2 J
B) 5 J
C) 10 J
D) 50 J
Answer: D
Rationale: ΔU = qΔV = (5 C)(10 V) = 50 J.
9. Which of the following is true regarding electric field lines?
A) They point from negative to positive charges.
B) They are closer together where the field is weaker.
C) They can cross each other.
D) They point from positive to negative charges.
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Answer: D
Rationale: Electric field lines originate on positive charges and terminate
on negative charges. They never cross, and density indicates field
strength.
10. A dipole consists of a +q and –q charge separated by a distance d. The
dipole moment p is:
A) qd
B) q/d
C) d/q
D) q²d
Answer: A
Rationale: The electric dipole moment is defined as the magnitude of the
charge times the separation distance: p = qd.
11. Gauss's Law relates the electric flux through a closed surface to:
A) The total charge enclosed by the surface
B) The electric field on the surface
C) The potential difference across the surface
D) The magnetic field inside the surface
Answer: A
Rationale: Gauss's Law states that the net electric flux through any closed
surface is equal to the total enclosed charge divided by ε₀.
12. A point charge is placed at the center of a spherical Gaussian surface.
If the radius of the sphere is doubled, the electric flux through the
surface:
A) Doubles
B) Quadruples
C) Halves
D) Remains the same
Answer: D
Rationale: Gauss's Law states that flux depends only on the enclosed
charge, not the size or shape of the Gaussian surface.
13. Two charges, +Q and +2Q, are separated by a distance d. At what point
on the line connecting them is the electric field zero?
