ELECTROMAGNETIC FIELDS & WAVES
EXAM QUESTION AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2026 Q&A INSTANT
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1. Which of the following is Gauss’s law in differential form?
A. ∇·B = 0
B. ∇×E = −∂B/∂t
C. ∇×H = J
D. ∇·E = ρ/ε₀
Answer: D
Rationale: Gauss’s law states that the divergence of the electric field
equals the charge density divided by permittivity.
2. The SI unit of electric flux density D is
A. V/m
B. C
C. C/m²
D. A/m
Answer: C
Rationale: Electric flux density is charge per unit area.
3. In free space, the relationship between E and D is
A. D = μ₀E
B. D = ε₀E
C. D = σE
D. D = E/ε₀
, Answer: B
Rationale: In free space, permittivity ε₀ relates E and D.
4. Which Maxwell equation explains electromagnetic wave propagation?
A. Gauss’s law
B. Faraday’s law
C. Ampere-Maxwell law
D. Combination of Faraday’s and Ampere-Maxwell laws
Answer: D
Rationale: Time-varying electric and magnetic fields sustain wave
propagation.
5. The divergence of magnetic flux density B is always
A. Positive
B. Negative
C. Zero
D. Infinite
Answer: C
Rationale: Magnetic monopoles do not exist, so ∇·B = 0.
6. Which field quantity is solenoidal?
A. E
B. D
C. B
D. J
Answer: C
Rationale: A solenoidal field has zero divergence, which applies to B.
7. The curl of the electric field in electrostatics is
A. Non-zero
B. Zero
C. Infinite
D. Constant
Answer: B
Rationale: Electrostatic fields are conservative.
, 8. The unit of magnetic field intensity H is
A. Tesla
B. Weber
C. A/m
D. V/m
Answer: C
Rationale: Magnetic field intensity is measured in amperes per meter.
9. Faraday’s law relates changing magnetic fields to
A. Magnetic force
B. Electric current
C. Electric field
D. Charge density
Answer: C
Rationale: A time-varying magnetic field induces an electric field.
10.The speed of electromagnetic waves in free space is
A. 3×10⁶ m/s
B. 3×10⁷ m/s
C. 3×10⁸ m/s
D. 3×10⁹ m/s
Answer: C
Rationale: The speed of light is 3×10⁸ m/s.
11.The intrinsic impedance of free space is approximately
A. 120π Ω
B. 377 Ω
C. 50 Ω
D. 75 Ω
Answer: B
Rationale: η₀ = √(μ₀/ε₀) ≈ 377 Ω.
EXAM QUESTION AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2026 Q&A INSTANT
DOWNLOAD PDF
1. Which of the following is Gauss’s law in differential form?
A. ∇·B = 0
B. ∇×E = −∂B/∂t
C. ∇×H = J
D. ∇·E = ρ/ε₀
Answer: D
Rationale: Gauss’s law states that the divergence of the electric field
equals the charge density divided by permittivity.
2. The SI unit of electric flux density D is
A. V/m
B. C
C. C/m²
D. A/m
Answer: C
Rationale: Electric flux density is charge per unit area.
3. In free space, the relationship between E and D is
A. D = μ₀E
B. D = ε₀E
C. D = σE
D. D = E/ε₀
, Answer: B
Rationale: In free space, permittivity ε₀ relates E and D.
4. Which Maxwell equation explains electromagnetic wave propagation?
A. Gauss’s law
B. Faraday’s law
C. Ampere-Maxwell law
D. Combination of Faraday’s and Ampere-Maxwell laws
Answer: D
Rationale: Time-varying electric and magnetic fields sustain wave
propagation.
5. The divergence of magnetic flux density B is always
A. Positive
B. Negative
C. Zero
D. Infinite
Answer: C
Rationale: Magnetic monopoles do not exist, so ∇·B = 0.
6. Which field quantity is solenoidal?
A. E
B. D
C. B
D. J
Answer: C
Rationale: A solenoidal field has zero divergence, which applies to B.
7. The curl of the electric field in electrostatics is
A. Non-zero
B. Zero
C. Infinite
D. Constant
Answer: B
Rationale: Electrostatic fields are conservative.
, 8. The unit of magnetic field intensity H is
A. Tesla
B. Weber
C. A/m
D. V/m
Answer: C
Rationale: Magnetic field intensity is measured in amperes per meter.
9. Faraday’s law relates changing magnetic fields to
A. Magnetic force
B. Electric current
C. Electric field
D. Charge density
Answer: C
Rationale: A time-varying magnetic field induces an electric field.
10.The speed of electromagnetic waves in free space is
A. 3×10⁶ m/s
B. 3×10⁷ m/s
C. 3×10⁸ m/s
D. 3×10⁹ m/s
Answer: C
Rationale: The speed of light is 3×10⁸ m/s.
11.The intrinsic impedance of free space is approximately
A. 120π Ω
B. 377 Ω
C. 50 Ω
D. 75 Ω
Answer: B
Rationale: η₀ = √(μ₀/ε₀) ≈ 377 Ω.
