Electromagnetic Waves NEET PYQReal NEET & AIPMT 2005–2021 questions, year-tagged, with solutions
By the RankUp team, founded by Dr. Deepak Sahu (MBBS Gold Medalist, NEET PG AIR 1731) · Updated
Every Electromagnetic Waves question from the NEET & AIPMT papers on this site (2005–2021), newest first. Each is tagged with its paper. Tap an option to check your answer and read the explanation.
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Electromagnetic Waves previous year questions
23 questions. Tap an option to check your answer.
Q1NEET 2021
For a plane electromagnetic wave propagating in x-direction, which one of the following combination gives the correct possible directions for electric field (E) and magnetic field (B) respectively ?
Not quite — the answer is B.
E and B must be perpendicular and E × B must point along +x. For E = −ĵ + k̂ and B = −ĵ − k̂: E·B = 1 − 1 = 0, and E × B = (−ĵ)×(−k̂) + k̂×(−ĵ) = î + î = 2î. The pairs with E and B along the same or opposite lines (such as ĵ + k̂ with −ĵ − k̂) give E × B = 0.
Q2NEET 2020 · Q137
The ratio of contributions made by the electric field and magnetic field components to the intensity of an electromagnetic wave is : (c = speed of electromagnetic waves)
Not quite — the answer is B.
The electric energy density ½ε₀E² equals the magnetic energy density B²/2μ₀ because E = cB and c² = 1/μ₀ε₀, so both fields contribute equally to intensity. The ratio E/B = c is about field amplitudes, not about energy.
Q3NEET 2020 · Q150
Light with an average flux of 20 W/cm² falls on a non-reflecting surface at normal incidence having surface area 20 cm². The energy received by the surface during time span of 1 minute is :
Not quite — the answer is C.
Power received = 20 W/cm² × 20 cm² = 400 W, and in 60 s the energy is 400 × 60 = 24×10³ J. Doubling for reflection is not needed because the surface is non-reflecting; that only affects momentum transfer anyway.
Q4NEET 2019 · Q8
Which colour of the light has the longest wavelength?
Not quite — the answer is A.
In the visible spectrum wavelength decreases from red (about 700 nm) to violet (about 400 nm), so red has the longest wavelength. Violet is the shortest-wavelength end.
Q5NEET 2019 · Q43
A parallel plate capacitor of capacitance 20 μF is being charged by a voltage source whose potential is changing at the rate of 3 V/s. The conduction current through the connecting wires, and the displacement current through the plates of the capacitor, would be, respectively:
Not quite — the answer is B.
Conduction current I = C dV/dt = 20 × 10⁻⁶ × 3 = 60 μA. Displacement current between the plates equals the conduction current in the wires, so both are 60 μA. Saying the displacement current is zero ignores Maxwell's correction.
Q6NEET 2018 · Q18
An em wave is propagating in a medium with a velocity V⃗ = Vî. The instantaneous oscillating electric field of this em wave is along +y axis. Then the direction of oscillating magnetic field of the em wave will be along
Not quite — the answer is B.
The direction of propagation is along E⃗ × B⃗. With E⃗ along ĵ and propagation along î, B⃗ must be along k̂ because ĵ × k̂ = î. Choosing −z would reverse the propagation direction.
Q7NEET 2017 (Gujarati paper) · Q146
Inside a parallel plate capacitor the electric field E varies with time as t². The variation of induced magnetic field with time is given by:
Not quite — the answer is C.
The induced magnetic field comes from the displacement current, I_d = ε₀ dΦ_E/dt, which is proportional to dE/dt. If E ∝ t², then dE/dt ∝ t, so B ∝ t. B ∝ t² would wrongly assume the field depends on E itself rather than on its rate of change.
Q8NEET 2016 Phase 2 · Q33
A 100 Ω resistance and a capacitor of 100 Ω reactance are connected in series across a 220 V source. When the capacitor is 50% charged, the peak value of the displacement current is
Not quite — the answer is A.
The displacement current between the plates equals the conduction current in the circuit. Impedance Z = √(100² + 100²) = 100√2 Ω, and the peak voltage of a 220 V (rms) supply is 220√2 V, so the peak current is 220√2/(100√2) = 2.2 A. The '50% charged' detail does not change the peak value.
Q9NEET 2016 Phase 1 · Q8
Out of the following options which one can be used to produce a propagating electromagnetic wave?
Not quite — the answer is D.
Only an accelerating charge produces time-varying electric and magnetic fields that detach and propagate as an electromagnetic wave. A stationary charge gives only a static field and a uniformly moving charge gives a steady current-like field that does not radiate.
Q10AIPMT 2015
A radiation of energy 'E' falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (C = Velocity of light):
Not quite — the answer is C.
Radiation of energy E carries momentum E/c. A perfect reflector sends it back with the same magnitude, so the change in momentum is E/c − (−E/c) = 2E/c. E/c would be the answer only for a perfectly absorbing surface.
Q11AIPMT 2014
Light with an energy flux of 25 × 10⁴ Wm⁻² falls on a perfectly reflecting surface at normal incidence. If the surface area is 15 cm², the average force exerted on the surface is:
Not quite — the answer is A.
For a perfect reflector the momentum change doubles, F = 2IA/c = 2 × 25 × 10⁴ × 15 × 10⁻⁴/(3 × 10⁸) = 2.5 × 10⁻⁶ N. Using IA/c (absorbing surface) would give half this.
Q12AIPMT 2012 Mains
The dimensions of (μ₀ε₀)^(−1/2) are
Not quite — the answer is C.
Since c = 1/√(μ₀ε₀), the quantity (μ₀ε₀)^(−1/2) is simply the speed of light and has dimensions [LT⁻¹]. The inverse [L⁻¹T] would be the dimensions of √(μ₀ε₀) itself.
Q13AIPMT 2012 Mains
The ratio of amplitude of magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to :
Not quite — the answer is B.
In vacuum E₀ = cB₀, so B₀/E₀ = 1/c, the reciprocal of the speed of light. The speed of light itself is the ratio E₀/B₀, the reverse.
Q14AIPMT 2012 Prelims
The electric field associated with an e.m. wave in vacuum is given by E⃗ = î 40 cos(kz − 6 × 10⁸ t), where E, z and t are in volt/m, metre and seconds respectively. The value of wave vector k is
Not quite — the answer is B.
From E = E₀ cos(kz − ωt), ω = 6 × 10⁸ rad s⁻¹. In vacuum c = ω/k, so k = 6 × 10⁸/(3 × 10⁸) = 2 m⁻¹. 0.5 m⁻¹ comes from inverting the ratio.
Q15AIPMT 2011 Prelims
The dimensions of (μ₀ε₀)^(−1/2) are
Not quite — the answer is D.
Since c = 1/√(μ₀ε₀), the quantity (μ₀ε₀)^(−1/2) is simply the speed of light and has dimensions [LT⁻¹]. The inverse [L⁻¹T] would be the dimensions of √(μ₀ε₀) itself, not its inverse root.
Q16AIPMT 2011 Prelims
The electric and the magnetic field, associated with an e.m. wave, propagating along the +z-axis, can be represented by
Not quite — the answer is B.
An EM wave travels along E⃗ × B⃗, with E and B perpendicular to each other and to the propagation direction. With E along î and B along ĵ, î × ĵ = k̂, i.e. +z. E along ĵ with B along î gives ĵ × î = −k̂, the reverse direction.
Q17AIPMT 2011 Prelims
The decreasing order of wavelength of infrared, microwave, ultraviolet and gamma rays is
Not quite — the answer is B.
In the EM spectrum wavelength falls from microwaves (mm–cm) to infrared (μm) to ultraviolet (~100 nm) to gamma rays (< 0.01 nm). The order starting with gamma rays is increasing, not decreasing, wavelength.
Q18AIPMT 2010 Mains · Q67
The electric field of an electromagnetic wave in free space is given by E⃗ = 10 cos(10⁷t + kx) ĵ V/m, where t and x are in seconds and metres respectively. It can be inferred that (a) The wavelength λ is 188.4 m (b) The wave number k is 0.33 rad/m (c) The wave amplitude is 10 V/m (d) The wave is propagating along +x direction Which one of the following pairs of statements is correct?
Not quite — the answer is D.
Here ω = 10⁷ rad/s, so k = ω/c = 10⁷/(3 × 10⁸) = 0.033 rad/m and λ = 2π/k ≈ 188.4 m; the amplitude is 10 V/m. So the wavelength and amplitude statements are correct. The wave number is 0.033, not 0.33 rad/m, and the phase (ωt + kx) means the wave travels along −x, not +x.
Q19AIPMT 2010 Prelims · Q22
Which of the following statement is false for the properties of electromagnetic waves?
Not quite — the answer is D.
In an electromagnetic wave E and B are perpendicular to each other and both perpendicular to the direction of propagation, so saying they are parallel to each other is false. The other statements (no medium needed, in-phase maxima, equal energy sharing) are true.
Q20AIPMT 2009 Prelims · Q49
The electric field part of an electromagnetic wave in a medium is represented by Ex = 0; Ey = 2.5 (N/C) cos[(2π × 10⁶ rad/s) t − (π × 10⁻² rad/m) x]; Ez = 0. The wave is:
Not quite — the answer is B.
Comparing with E₀cos(ωt − kx): ω = 2π × 10⁶ rad/s gives f = 10⁶ Hz, and k = π × 10⁻² rad/m gives λ = 2π/k = 200 m. The (ωt − kx) form means propagation along +x. Taking f = 2π × 10⁶ Hz confuses ω with f.
Q21AIPMT 2008 Prelims · Q21
The velocity of electromagnetic radiation in a medium of permittivity ε₀ and permeability μ₀ is given by
Not quite — the answer is D.
Maxwell's equations give the wave speed v = 1/√(με); with ε₀ and μ₀ this is c = 1/√(μ₀ε₀) ≈ 3 × 10⁸ m/s. √(μ₀ε₀) is its inverse, with dimensions of time per length, and √(μ₀/ε₀) is the impedance of free space (in ohms), not a speed.
Q22AIPMT 2007 Prelims · Q43
The electric and magnetic field of an electromagnetic wave are
Not quite — the answer is C.
In a plane EM wave, E and B oscillate in phase (both reach maxima together) and are perpendicular to each other and to the direction of propagation.
Q23AIPMT 2005 Prelims · Q39
If λv, λx and λm represent the wavelengths of visible light, X-rays and microwaves respectively, then :
Not quite — the answer is C.
In the EM spectrum microwaves (mm–cm) are longer than visible light (400–700 nm), which is longer than X-rays (≈ 0.01–10 nm). So λm > λv > λx.
How often Electromagnetic Waves came up
Questions from this chapter in each paper on this site.
- NEET 2021: 1
- NEET 2020: 2
- NEET 2019: 2
- NEET 2018: 1
- NEET 2017 (Gujarati paper): 1
- NEET 2016 Phase 2: 1
- NEET 2016 Phase 1: 1
- AIPMT 2015: 1
- AIPMT 2014: 1
- AIPMT 2012 Mains: 2
- AIPMT 2012 Prelims: 1
- AIPMT 2011 Prelims: 3
- AIPMT 2010 Mains: 1
- AIPMT 2010 Prelims: 1
- AIPMT 2009 Prelims: 1
- AIPMT 2008 Prelims: 1
- AIPMT 2007 Prelims: 1
- AIPMT 2005 Prelims: 1
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