JEE Main Physics · Modern Physics PYQ
JEE Main Modern Physics Previous Year Questions (2002–2026)
Modern Physics is a P1 high-ROI chapter — ~7% JEE Main weightage with 1–2 questions per session and elite ROI relative to prep time. The chapter is short, formula-heavy and near-zero variance year-to-year. Students who over-prepare Modern Physics recover 5–8 marks that others leave on the table.
Modern Physics PYQs from 2002 to 2026, spanning Dual Nature (photoelectric effect, de Broglie), Atoms (Bohr model, hydrogen spectrum) and Nuclei (radioactivity, binding energy, fission/fusion). Each solution derives from the fundamental formula set.
Modern Physics at a Glance
Try 5 Real Modern Physics PYQs
5 real JEE Main questions on Modern Physics, straight from past papers. Try them, then check the answer.
- Q1JEE Main 2026 (Online) 22nd January Evening Shift
Light is incident on a metallic plate having work function $110 \times 10^{-20} \mathrm{~J}$. If the produced photoelectrons have zero kinetic energy then the angular frequency of the incident light is $\_\_\_\_$ rad/s. $\left(\mathrm{h}=6.63 \times 10^{-34} \mathrm{~J} . \mathrm{s}\right)$.
$1.04 \times 10^{13}$
$1.66 \times 10^{16}$
$1.66 \times 10^{15}$
$1.04 \times 10^{16}$
- Q2JEE Main 2026 (Online) 21st January Morning Shift
If an alpha particle with energy 7.7 MeV is bombarded on a thin gold foil, the closest distance from nucleus it can reach is $\_\_\_\_$ m. (Atomic number of gold $=79$ and $\frac{1}{4 \pi \epsilon_{\mathrm{o}}}$${}=9 \times 10^9$ in SI units)
$2.95 \times 10^{-16}$
$3.85 \times 10^{-14}$
$2.95 \times 10^{-14}$
$3.85 \times 10^{-16}$
- Q3JEE Main 2025 (Online) 28th January Evening Shift
Which of the following phenomena cannot be explained by wave theory of light?
Refraction of light
Reflection of light
Diffraction of light
Compton effect
- Q4JEE Main 2025 (Online) 23rd January Morning Shift
A radioactive nucleus $\mathrm{n}_2$ has 3 times the decay constant as compared to the decay constant of another radioactive nucleus $n_1$. If initial number of both nuclei are the same, what is the ratio of number of nuclei of $n_2$ to the number of nuclei of $n_1$, after one half-life of $n_1$ ?
- 1/4
- 1/8
- 4
- 8
- Q5JEE Main 2024 (Online) 29th January Evening Shift
Two sources of light emit with a power of 200 W. The ratio of number of photons of visible light emitted by each source having wavelengths 300 nm and 500 nm respectively, will be :
- $5: 3$
- $3: 5$
- $1: 5$
- $1: 3$
Practise the full Modern Physics set
Every past-paper question of this chapter, with solutions, timing and your accuracy tracked.
Key Sub-Topics & What's Tested
Photoelectric Effect
Einstein's equation (hν = φ + KE_max), threshold frequency, stopping potential, intensity vs frequency effects.
de Broglie Waves
Wavelength λ = h/p for matter waves, Davisson-Germer experiment, wave nature of electrons.
Bohr Atomic Model
Quantised orbits, radius r_n ∝ n², energy E_n ∝ -1/n², angular momentum mvr = nh/2π.
Hydrogen Spectrum
Lyman, Balmer, Paschen series, Rydberg formula 1/λ = R(1/n₁² - 1/n₂²), transitions and energy levels.
Atomic Nuclei — Size & Structure
Nuclear radius R = R₀A^(1/3), mass defect, binding energy per nucleon curve.
Radioactivity
α, β, γ decay laws, half-life (T½ = 0.693/λ), activity A = λN, mean life τ = 1/λ.
Nuclear Fission & Fusion
Energy released in fission (U-235) and fusion (H → He), mass-energy equivalence, binding energy peaks at Fe-56.
X-rays
Continuous and characteristic X-ray spectra, Moseley's law, minimum wavelength at given accelerating voltage.
Question Type Distribution
| Question Type | Share (approx) | Example Pattern |
|---|---|---|
| Photoelectric Formula Application | 25% | Light of frequency 2f₀ incident on surface with threshold f₀ — find KE_max. |
| Bohr Model Calculations | 20% | Find wavelength of Lyman α line using Rydberg formula. |
| de Broglie Wavelength | 15% | Find de Broglie wavelength of electron accelerated through 150 V. |
| Radioactive Decay | 20% | Fraction of sample remaining after 3 half-lives. |
| Binding Energy & Mass Defect | 10% | Find energy released when 2H + 3H → 4He + n, given masses. |
| Hydrogen Spectrum Identification | 10% | Identify which series produces 656 nm spectral line (Balmer α). |
How to Solve Modern Physics PYQs
- 1Memorise the Rydberg formula and key transitions. Lyman (UV, n→1), Balmer (visible, n→2), Paschen (IR, n→3). Wavelengths of first few lines of each series come up directly.
- 2Lock the photoelectric equation. hν = φ + KE_max = φ + eV_stop. Almost every photoelectric PYQ uses this single equation rearranged.
- 3de Broglie for electrons: λ = 12.27/√V Å. For an electron accelerated through V volts, this shortcut bypasses full derivation.
- 4Half-life: use N = N₀/2^(t/T½). Fraction remaining after n half-lives is 1/2ⁿ. Simple exponential recall.
- 5For binding energy questions, remember 1 amu = 931.5 MeV. Mass defect × 931.5 = binding energy. Standard conversion.
Common Mistakes That Cost Marks
- Using wrong Rydberg constant units. R = 1.097 × 10⁷ m⁻¹. Substituting wrong units gives wavelengths off by factors of 10.
- Confusing threshold frequency and stopping potential. Threshold frequency depends only on metal. Stopping potential depends on both incident frequency and metal.
- Treating photons as massive particles. Photons have momentum p = h/λ but zero rest mass. de Broglie works for matter, photoelectric formula for light — don't cross apply.
- Forgetting the Einstein 931.5 conversion in nuclear problems. Without this, mass defect stays as amu without converting to MeV.
- Wrong sign for hydrogen energy levels. E_n = -13.6/n² eV. The negative sign is critical — transitions release or absorb energy equal to difference.
Related JEE Main Practice
Frequently asked questions
How many Modern Physics PYQs should I solve?
Target 50–70 PYQs across 2010–2026. Modern Physics is a short, high-yield chapter — 30 hours of focused practice consistently delivers 4–5 marks per mock test.
Is Modern Physics more formula-heavy or conceptual?
More formula-heavy. Bohr model, photoelectric equation, de Broglie, Rydberg — all reducible to substitution problems once you know the formulas. Conceptual questions are rare.
Do I need relativity for JEE Main Modern Physics?
Only Einstein's mass-energy equivalence E = mc² for nuclear problems. No special relativity (time dilation, length contraction) — that's beyond syllabus.
Which transition gives 656 nm spectral line?
Hydrogen Balmer α — transition from n=3 to n=2. This is Hα line, the brightest red line in the visible hydrogen spectrum. Direct PYQ answer.
How does photoelectric effect PYQ usually appear?
Usually asks for KE_max, stopping potential, or threshold frequency given two of the three. Uses Einstein's equation. Roughly 2–3 variants per 10-year window.
Is X-rays a separate PYQ topic?
Yes — ~2–3 X-ray questions per 10-year window. Usually on minimum wavelength (λ_min = hc/eV) and Moseley's law (√ν = a(Z-b)) for characteristic X-rays.
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