Maxwell's Electromagnetic Theory — NEET Physics MCQs with Solutions
Free NEET Physics Maxwell's Electromagnetic Theory MCQs with step-by-step solutions (18 questions). Part of Wave Theory of Light. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Maxwell's Electromagnetic Theory · easy · theory
According to Maxwell's electromagnetic theory, light is:
A. A longitudinal mechanical wave
B. A stream of photons only
C. A transverse electromagnetic wave ✓ Correct
D. A stream of corpuscles
Solution: Maxwell showed that light is a transverse electromagnetic wave consisting of oscillating electric and magnetic fields.
Q2 — Maxwell's Electromagnetic Theory · easy · theory
In an electromagnetic wave, the electric field (E), magnetic field (B) and direction of propagation are:
A. Mutually perpendicular to one another ✓ Correct
B. E parallel to B, both perpendicular to propagation
C. E and B along the direction of propagation
D. All parallel to one another
Solution: E, B and the direction of propagation form a mutually perpendicular right-handed set; E and B oscillate in phase.
Q3 — Maxwell's Electromagnetic Theory · medium · theory
The speed of an electromagnetic wave in free space is given by:
A. $c = \dfrac{\mu_0}{\varepsilon_0}$
B. $c = \sqrt{\mu_0 \varepsilon_0}$
C. $c = \dfrac{1}{\sqrt{\mu_0 \varepsilon_0}}$ ✓ Correct
D. $c = \mu_0 \varepsilon_0$
Solution: Maxwell derived c = 1/√(μ₀ε₀) ≈ 3 × 10⁸ m/s, matching the measured speed of light and identifying light as an EM wave.
Q4 — Maxwell's Electromagnetic Theory · medium · theory
In an electromagnetic wave, the ratio of the amplitude of the electric field (E₀) to that of the magnetic field (B₀) equals:
A. 1/c
B. The speed of light, c ✓ Correct
C. c²
D. 1
Solution: For an EM wave E₀/B₀ = c; the electric and magnetic field magnitudes are related by E = cB at every instant.
Q5 — Maxwell's Electromagnetic Theory · medium · theory
For a non-magnetic transparent medium of relative permittivity εᵣ, the refractive index according to electromagnetic theory is:
A. $n = \sqrt{\varepsilon_r}$ ✓ Correct
B. $n = \varepsilon_r^2$
C. $n = 1/\sqrt{\varepsilon_r}$
D. $n = \varepsilon_r$
Solution: n = √(μᵣεᵣ); for a non-magnetic medium μᵣ ≈ 1, so n = √εᵣ (Maxwell's relation).
Q6 — Maxwell's Electromagnetic Theory · medium · theory
A key advantage of Maxwell's electromagnetic theory over earlier mechanical wave models was that light:
A. Is made of particles with mass
B. Does not require a material medium and can travel through vacuum ✓ Correct
C. Must travel through the luminiferous ether
D. Cannot carry energy or momentum
Solution: EM waves are self-sustaining oscillations of electric and magnetic fields and need no material medium, so light can travel through vacuum.
Q7 — Maxwell's Electromagnetic Theory · easy · theory
Electromagnetic waves were first experimentally produced and detected by:
A. Augustin Fresnel
B. Thomas Young
C. James Clerk Maxwell
D. Heinrich Hertz ✓ Correct
Solution: Heinrich Hertz experimentally generated and detected electromagnetic waves, confirming Maxwell's theoretical prediction.
Q8 — Maxwell's Electromagnetic Theory · medium · theory
The energy in an electromagnetic wave is:
A. Entirely in the magnetic field
B. Independent of both fields
C. Shared equally between the electric and magnetic fields ✓ Correct
D. Entirely in the electric field
Solution: The average energy density is shared equally between the electric and magnetic field components of the wave.
Q9 — Maxwell's Electromagnetic Theory · medium · theory
Which of the following phenomena could NOT be explained by Maxwell's electromagnetic wave theory of light?
A. Diffraction of light
B. The photoelectric effect ✓ Correct
C. Interference of light
D. Polarisation of light
Solution: Maxwell's wave theory explained interference, diffraction and polarisation, but failed to explain the photoelectric effect and black-body radiation, which required the quantum theory.
Q10 — Maxwell's Electromagnetic Theory · medium · numerical
In a medium of refractive index n, the speed of light is v = c/n. Using Maxwell's theory, if a medium has εᵣ = 4 (and μᵣ ≈ 1), the speed of light in it is:
A. $6 \times 10^{8}$ m/s
B. $1.5 \times 10^{8}$ m/s ✓ Correct
C. $0.75 \times 10^{8}$ m/s
D. $3 \times 10^{8}$ m/s
Solution: n = √εᵣ = √4 = 2, so v = c/n = (3 × 10⁸)/2 = 1.5 × 10⁸ m/s.
Q11 — Maxwell's Electromagnetic Theory · medium · numerical
A non-magnetic medium has relative permittivity εᵣ = 4. The speed of light in it (c = 3 × 10⁸ m/s) is:
A. 3 × 10⁸ m/s
B. 0.75 × 10⁸ m/s
C. 6 × 10⁸ m/s
D. 1.5 × 10⁸ m/s ✓ Correct
Solution: n = √εᵣ = 2; v = c/n = 3 × 10⁸/2 = 1.5 × 10⁸ m/s.
Q12 — Maxwell's Electromagnetic Theory · medium · numerical
The relative permittivity of a non-magnetic medium of refractive index 1.5 is:
A. 3
B. 0.67
C. 1.5
D. 2.25 ✓ Correct
Solution: n = √εᵣ ⇒ εᵣ = n² = 1.5² = 2.25.
Q13 — Maxwell's Electromagnetic Theory · medium · numerical
In an EM wave the magnetic field amplitude is 2 × 10⁻⁶ T. The electric field amplitude (c = 3 × 10⁸ m/s) is:
A. 150 V/m
B. 6.7 × 10⁻¹⁵ V/m
C. 300 V/m
D. 600 V/m ✓ Correct
Solution: E₀ = cB₀ = 3 × 10⁸ × 2 × 10⁻⁶ = 600 V/m.
Q14 — Maxwell's Electromagnetic Theory · medium · numerical
An EM wave has electric field amplitude 9 V/m. Its magnetic field amplitude (c = 3 × 10⁸ m/s) is:
A. 3 × 10⁻⁸ T ✓ Correct
B. 9 T
C. 3 × 10⁸ T
D. 2.7 × 10⁹ T
Solution: B₀ = E₀/c = 9/(3 × 10⁸) = 3 × 10⁻⁸ T.
Q15 — Maxwell's Electromagnetic Theory · medium · numerical
A non-magnetic medium has εᵣ = 9. The refractive index and speed of light in it are:
A. n = 1.5, v = 2 × 10⁸ m/s
B. n = 3, v = 9 × 10⁸ m/s
C. n = 9, v = 3.3 × 10⁷ m/s
D. n = 3, v = 1 × 10⁸ m/s ✓ Correct
Solution: n = √9 = 3; v = c/n = 3 × 10⁸/3 = 1 × 10⁸ m/s.
Q16 — Maxwell's Electromagnetic Theory · medium · numerical
A medium has refractive index 2 (non-magnetic). Its relative permittivity is:
A. 8
B. 4 ✓ Correct
C. 2
D. 1.4
Solution: εᵣ = n² = 4.
Q17 — Maxwell's Electromagnetic Theory · hard · numerical
Light of wavelength 600 nm (vacuum) enters a medium of εᵣ = 2.25 (non-magnetic). Its wavelength in the medium is:
A. 900 nm
B. 400 nm ✓ Correct
C. 600 nm
D. 267 nm
Solution: n = √2.25 = 1.5; λ_medium = 600/1.5 = 400 nm.
Q18 — Maxwell's Electromagnetic Theory · medium · numerical
For a non-magnetic medium with εᵣ = 16, the speed of light in it (c = 3 × 10⁸ m/s) is:
A. 1.5 × 10⁸ m/s
B. 0.75 × 10⁸ m/s ✓ Correct
C. 3 × 10⁸ m/s
D. 12 × 10⁸ m/s
Solution: n = √16 = 4; v = c/4 = 0.75 × 10⁸ m/s.