PHY 112 EXAM 2 | QUESTIONS
AND ANSWERS | 2026 UPDATED |
100% CORRECT - ASU.
90 Questions with Answers and Detailed Rationales
100 PERCENT GUARANTEED PASS
INSTANT DOWNLOAD ANSWERS INCLUDED
IMPORTANCE OF THIS DOCUMENT
This comprehensive examination preparation guide has been meticulously developed to help you succeed in the
PHY 112 EXAM 2 | QUESTIONS AND ANSWERS | 2026 UPDATED | 100% CORRECT - ASU.. It contains 90
carefully selected questions that reflect the most current exam content and testing strategies. Each question is
accompanied by a correct answer and a detailed rationale that explains the underlying pathophysiology,
pharmacology, or clinical reasoning.
Self-Assessment – Test your knowledge and Exam Preparation – Familiarize yourself with the
identify areas requiring further question format and content
study areas
Concept Reinforcement – Deepen your Confidence Building – Develop test-taking
understanding through strategies and reduce
evidence-based exam anxiety
rationales
Time Management – Practice answering
questions under simulated
exam conditions
Review Summary 90 Questions
Foundations - Application - PHY 112 2 AND 2026 Updated 100 Correct - ASU Physics Electricity AND
Magnetism Undergraduate YEAR 2 / Sophomore
All answers with rationales
,Table of Contents
Content Area Questions Key Topics
Electric Forces AND Fields 1-15 Light, Circuit, Current, Field, Distance
Gauss S LAW 16-30 Wavelength, Current, Field, Radius, Direction
Electric Potential AND 31-45 Field, Radius, Charge, Period, Magnetic
Potential Energy
Capacitance AND Dielectrics 46-60 Temperature, System, Energy, Speed, Constant
Current AND Resistance 61-75 Field, Magnetic, Ideal GAS, Electric, Current
DC Circuits 76-90 Cycle, Reservoir, Expansion, Isothermal, Primary
TOTAL 90 All questions include answers and detailed rationales
,Section A - Electric Forces AND Fields
Q1.
A solid insulating sphere of radius R has a non-uniform charge density (r) = (r/R)². Find
the electric potential at the center of the sphere, taking V=0 at infinity.
A. R²/(4) B. R²/(6)
C. R²/(3) D. R²/(12)
Correct: C - R²/(3)
Rationale:The electric field inside the sphere is found via Gauss's law: E(r) = Á €r³/(5µ €R²).
The potential at the center is the integral of E from 0 to R plus the potential at the surface
(kQ/R). This yields V(0) = R²/(3). The other options result from incorrect integration or field
expressions.
Q2.
A parallel-plate capacitor is filled with two dielectric slabs of equal area A, each of
thickness d/2, with dielectric constants and . The plates are separated by distance d.
What is the capacitance?
A. A(+)/(2d) B. A(2)/(d(+))
C. A()/(d(+)) D. A(+)/(d)
Correct: B - A(2)/(d(+))
Rationale:The two dielectric layers are in series, so the total capacitance is the reciprocal of
the sum of reciprocals: C = 1/(1/C + 1/C) with C = A/(d/2) and C = A/(d/2), leading to C =
A(2)/(d(+)). Option A is the parallel combination, C is an incorrect series formula, and D
neglects the series arrangement.
Q3.
In the circuit shown, the switch has been closed for a long time. At t=0, the switch is
opened. What is the current through the 2 k resistor immediately after opening? (Assume
the battery is ideal, R=1 k, R=2 k, C=10 F, V=12 V.)
A. 0 mA B. 4 mA
C. 6 mA D. 12 mA
Correct: B - 4 mA
Page 3
, Section A - Electric Forces AND Fields
Rationale: Before opening, the capacitor is fully charged and acts as an open circuit, so the
current through R is V/(R+R) = 12/(1+2) = 4 mA. Immediately after opening, the capacitor
maintains the voltage across R (since it was fully charged), so the current through R remains
4 mA. Option A would be true after the capacitor discharges, C is the current if R were
shorted, and D is the current through R only.
Q4.
A long straight wire carries a current I. A rectangular loop of dimensions a (width) and b
(height) is placed with its plane containing the wire, and its nearest side at distance d from
the wire. The loop moves away from the wire with constant speed v. What is the
magnitude of the induced emf in the loop?
A. Iabv/(2d(d+a)) B. Iabv/(2d²)
C. Iav/(2d) D. Iabv/(2d(d+b))
Correct: A - Iabv/(2d(d+a))
Rationale:The magnetic field varies across the loop, so the flux is ¦ = "+ B dA = (¼ €I/(2À))
ln((d+a)/d) times b. Differentiating with respect to time (v = dd/dt) gives = Iabv/(2d(d+a)).
Option B is the field at the near side only, C is the emf for a single moving rod, and D uses the
wrong dimension.
Q5.
An electromagnetic wave in vacuum has an electric field amplitude E and a magnetic field
amplitude B. If the frequency is doubled, what happens to the average energy density?
A. It quadruples B. It doubles
C. It stays the same D. It halves
Correct: C - It stays the same
Rationale:The average energy density of an EM wave is u = (1/2)µ €E €² + (1/2)B €²/¼ € =
E², which depends only on the amplitudes, not on frequency. Doubling the frequency changes
the wavelength and photon energy, but the classical energy density remains unchanged if
amplitudes are fixed. Options A, B, D incorrectly relate energy to frequency.
Q6.
Which of the following statements about Maxwell's equations is correct?
A. The divergence of the magnetic field is B. The curl of the electric field is always
proportional to the magnetic charge density. zero in static situations.
Page 4
AND ANSWERS | 2026 UPDATED |
100% CORRECT - ASU.
90 Questions with Answers and Detailed Rationales
100 PERCENT GUARANTEED PASS
INSTANT DOWNLOAD ANSWERS INCLUDED
IMPORTANCE OF THIS DOCUMENT
This comprehensive examination preparation guide has been meticulously developed to help you succeed in the
PHY 112 EXAM 2 | QUESTIONS AND ANSWERS | 2026 UPDATED | 100% CORRECT - ASU.. It contains 90
carefully selected questions that reflect the most current exam content and testing strategies. Each question is
accompanied by a correct answer and a detailed rationale that explains the underlying pathophysiology,
pharmacology, or clinical reasoning.
Self-Assessment – Test your knowledge and Exam Preparation – Familiarize yourself with the
identify areas requiring further question format and content
study areas
Concept Reinforcement – Deepen your Confidence Building – Develop test-taking
understanding through strategies and reduce
evidence-based exam anxiety
rationales
Time Management – Practice answering
questions under simulated
exam conditions
Review Summary 90 Questions
Foundations - Application - PHY 112 2 AND 2026 Updated 100 Correct - ASU Physics Electricity AND
Magnetism Undergraduate YEAR 2 / Sophomore
All answers with rationales
,Table of Contents
Content Area Questions Key Topics
Electric Forces AND Fields 1-15 Light, Circuit, Current, Field, Distance
Gauss S LAW 16-30 Wavelength, Current, Field, Radius, Direction
Electric Potential AND 31-45 Field, Radius, Charge, Period, Magnetic
Potential Energy
Capacitance AND Dielectrics 46-60 Temperature, System, Energy, Speed, Constant
Current AND Resistance 61-75 Field, Magnetic, Ideal GAS, Electric, Current
DC Circuits 76-90 Cycle, Reservoir, Expansion, Isothermal, Primary
TOTAL 90 All questions include answers and detailed rationales
,Section A - Electric Forces AND Fields
Q1.
A solid insulating sphere of radius R has a non-uniform charge density (r) = (r/R)². Find
the electric potential at the center of the sphere, taking V=0 at infinity.
A. R²/(4) B. R²/(6)
C. R²/(3) D. R²/(12)
Correct: C - R²/(3)
Rationale:The electric field inside the sphere is found via Gauss's law: E(r) = Á €r³/(5µ €R²).
The potential at the center is the integral of E from 0 to R plus the potential at the surface
(kQ/R). This yields V(0) = R²/(3). The other options result from incorrect integration or field
expressions.
Q2.
A parallel-plate capacitor is filled with two dielectric slabs of equal area A, each of
thickness d/2, with dielectric constants and . The plates are separated by distance d.
What is the capacitance?
A. A(+)/(2d) B. A(2)/(d(+))
C. A()/(d(+)) D. A(+)/(d)
Correct: B - A(2)/(d(+))
Rationale:The two dielectric layers are in series, so the total capacitance is the reciprocal of
the sum of reciprocals: C = 1/(1/C + 1/C) with C = A/(d/2) and C = A/(d/2), leading to C =
A(2)/(d(+)). Option A is the parallel combination, C is an incorrect series formula, and D
neglects the series arrangement.
Q3.
In the circuit shown, the switch has been closed for a long time. At t=0, the switch is
opened. What is the current through the 2 k resistor immediately after opening? (Assume
the battery is ideal, R=1 k, R=2 k, C=10 F, V=12 V.)
A. 0 mA B. 4 mA
C. 6 mA D. 12 mA
Correct: B - 4 mA
Page 3
, Section A - Electric Forces AND Fields
Rationale: Before opening, the capacitor is fully charged and acts as an open circuit, so the
current through R is V/(R+R) = 12/(1+2) = 4 mA. Immediately after opening, the capacitor
maintains the voltage across R (since it was fully charged), so the current through R remains
4 mA. Option A would be true after the capacitor discharges, C is the current if R were
shorted, and D is the current through R only.
Q4.
A long straight wire carries a current I. A rectangular loop of dimensions a (width) and b
(height) is placed with its plane containing the wire, and its nearest side at distance d from
the wire. The loop moves away from the wire with constant speed v. What is the
magnitude of the induced emf in the loop?
A. Iabv/(2d(d+a)) B. Iabv/(2d²)
C. Iav/(2d) D. Iabv/(2d(d+b))
Correct: A - Iabv/(2d(d+a))
Rationale:The magnetic field varies across the loop, so the flux is ¦ = "+ B dA = (¼ €I/(2À))
ln((d+a)/d) times b. Differentiating with respect to time (v = dd/dt) gives = Iabv/(2d(d+a)).
Option B is the field at the near side only, C is the emf for a single moving rod, and D uses the
wrong dimension.
Q5.
An electromagnetic wave in vacuum has an electric field amplitude E and a magnetic field
amplitude B. If the frequency is doubled, what happens to the average energy density?
A. It quadruples B. It doubles
C. It stays the same D. It halves
Correct: C - It stays the same
Rationale:The average energy density of an EM wave is u = (1/2)µ €E €² + (1/2)B €²/¼ € =
E², which depends only on the amplitudes, not on frequency. Doubling the frequency changes
the wavelength and photon energy, but the classical energy density remains unchanged if
amplitudes are fixed. Options A, B, D incorrectly relate energy to frequency.
Q6.
Which of the following statements about Maxwell's equations is correct?
A. The divergence of the magnetic field is B. The curl of the electric field is always
proportional to the magnetic charge density. zero in static situations.
Page 4
