JEE (Main) · Physics, Class 12
Dual Nature of Matter and Radiation: JEE Main PYQ, 2020–2025
Dual Nature of Matter and Radiation (Physics, Class 12) has been asked 114 times in the 111 JEE (Main) shift papers from 2020–2025: about 1 questions a paper, 4% of all Physics questions. It is the 16th most-asked of 20 Physics chapters. The 2025 shifts had 12 from it in all. Last checked 28 October 2026.
Questions per year, all shifts
Year by year.
| Year | Questions |
|---|---|
| 2020 | 16in 14 papers |
| 2021 | 30in 26 papers |
| 2022 | 24in 24 papers |
| 2023 | 13in 12 papers |
| 2024 | 19in 18 papers |
| 2025 | 12in 17 papers |
JEE (Main) is sat in many shifts a year, each with its own paper; the counts add up every shift. 2021–2024 papers had 30 questions a subject, the others 25.
Inside the chapter
Topics asked most.
- Photoelectric effect60
- de Broglie wavelength54
Try it
10 Dual Nature of Matter and Radiation questions to practise.
Our own questions, written in the JEE Main pattern and checked, each with an explanation. Pick an option to see the answer.
Q1 · Physics · Dual Nature of Matter and Radiation
Light of photon energy 5 eV falls on a metal of work function 2 eV. What is the stopping potential?
Answer: (B)
K(max) = hν − φ = 5 − 2 = 3 eV. The stopping potential V₀ satisfies eV₀ = K(max), so V₀ = 3 V.
Q2 · Physics · Dual Nature of Matter and Radiation
A photon and a slow-moving electron have the same wavelength. Which of these quantities is then the same for both?
Answer: (D)
The relation λ = h/p holds for a photon as well as for a material particle, so equal wavelengths mean equal momenta. Their energies differ: the photon has pc, and the slow electron a kinetic energy of p²/2m, which is pc multiplied by v/2c.
Q3 · Physics · Dual Nature of Matter and Radiation
Light of wavelength 400 nm falls on a metal of work function 2.1 eV. The wavelength is then changed to 200 nm. By what factor does the maximum kinetic energy of the photoelectrons increase? (hc = 1240 eV nm)
Answer: (A)
At 400 nm the photon energy is 1240/400 = 3.1 eV, so K_max = 3.1 − 2.1 = 1.0 eV. At 200 nm it is 6.2 eV, so K_max = 6.2 − 2.1 = 4.1 eV. The kinetic energy rises 4.1 times although the photon energy only doubles, because the same work function is subtracted each time.
Q4 · Physics · Dual Nature of Matter and Radiation
An electron and a proton have the same kinetic energy. Which has the longer de Broglie wavelength?
Answer: (A)
λ = h/p = h / √(2mK). At the same kinetic energy, the lighter electron has the smaller momentum and therefore the longer wavelength.
Q5 · Physics · Dual Nature of Matter and Radiation
A metal has a work function of 3.3 eV. What is its threshold frequency? (h = 6.6 × 10⁻³⁴ J s; 1 eV = 1.6 × 10⁻¹⁹ J)
Answer: (D)
ν₀ = φ₀/h = (3.3 × 1.6 × 10⁻¹⁹ J) / (6.6 × 10⁻³⁴ J s) = 8 × 10¹⁴ Hz. Light of lower frequency cannot eject electrons from this metal, however intense it is.
Q6 · Physics · Dual Nature of Matter and Radiation
A small photocell is lit by a point source of monochromatic light placed 0.5 m away. The source is then moved to 1.0 m from the cell. Compared with before:
Answer: (D)
The intensity at the cell varies as 1/r², so at twice the distance it is one-quarter, and the saturation current, which is proportional to the intensity, falls to one-quarter. The frequency is the same, so the maximum kinetic energy of the photoelectrons, and with it the stopping potential, stays as it was.
Q7 · Physics · Dual Nature of Matter and Radiation
In a photoelectric experiment, the stopping potential V₀ is plotted against the frequency ν of the incident light. What does the slope of the graph equal? (h is the Planck constant and e the electronic charge.)
Answer: (C)
eV₀ = hν − φ₀ gives V₀ = (h/e)ν − φ₀/e, a straight line of slope h/e ≈ 4.14 × 10⁻¹⁵ V s, the same for every metal; only the intercept depends on the metal.
Q8 · Physics · Dual Nature of Matter and Radiation
Hydrogen gas (molar mass 2 g mol⁻¹) and oxygen gas (molar mass 32 g mol⁻¹) are both at the same temperature. The de Broglie wavelength of each molecule is calculated from its mean translational kinetic energy, (3/2)k_BT. What is the ratio λ(H₂) : λ(O₂)?
Answer: (A)
The de Broglie wavelength is λ = h/p, and p = √(2mK). At the same temperature the mean translational kinetic energy K = (3/2)k_BT is the same for both gases. So λ = h/√(2mK) is proportional to 1/√m. Then λ(H₂)/λ(O₂) = √(m(O₂)/m(H₂)) = √(32/2) = √16 = 4. The lighter hydrogen molecule has the longer wavelength.
Q9 · Physics · Dual Nature of Matter and Radiation
An electron and an alpha particle (a helium nucleus, charge +2e) are each accelerated from rest, the electron through a potential difference V_e and the alpha particle through V_α. Both end up with the same de Broglie wavelength. Treat both as non-relativistic and take m_α = 7344 m_e. What is the ratio V_e / V_α?
Answer: (A)
The de Broglie wavelength is λ = h/p. For equal wavelengths the momenta must be equal. A particle of charge q accelerated through V from rest has kinetic energy qV, so p = √(2mqV). Setting the momenta equal gives m_e·e·V_e = m_α·(2e)·V_α. Hence V_e/V_α = 2m_α/m_e = 2 × 7344 = 14688. The electron needs a much larger potential because it is far lighter. The alpha particle's double charge means it needs only half the potential its mass alone would suggest, which is why the factor of 2 multiplies the mass ratio.
Q10 · Physics · Dual Nature of Matter and Radiation
An electron of mass 9.1 × 10⁻³¹ kg moves with a speed of 2.0 × 10⁶ m s⁻¹. Taking Planck's constant h = 6.6 × 10⁻³⁴ J s, what is its de Broglie wavelength?
Answer: (A)
The de Broglie relation links the wavelength of a matter wave to its momentum: λ = h/p, where p = mv for a non-relativistic particle. Here p = (9.1 × 10⁻³¹ kg)(2.0 × 10⁶ m s⁻¹) = 1.82 × 10⁻²⁴ kg m s⁻¹. Then λ = 6.6 × 10⁻³⁴ / 1.82 × 10⁻²⁴ ≈ 3.6 × 10⁻¹⁰ m. Keep track of the powers of ten: −34 minus −24 gives −10. Since the speed is far below c, the non-relativistic formula is valid.
Free with an account
All 114 real JEE Main questions from Dual Nature of Matter and Radiation.
The questions from the actual papers, with the official answer and an explanation for each — chapter by chapter, or as full timed papers.
Solve them freeQuestions
About Dual Nature of Matter and Radiation in JEE Main.
How many questions come from Dual Nature of Matter and Radiation in JEE Main?
Dual Nature of Matter and Radiation (Physics, Class 12) has been asked 114 times in the 111 JEE (Main) shift papers from 2020–2025: about 1 questions a paper, 4% of all Physics questions. It is the 16th most-asked of 20 Physics chapters. The 2025 shifts had 12 from it in all.
Which topics of Dual Nature of Matter and Radiation are asked most in JEE Main?
Photoelectric effect (60), de Broglie wavelength (54), counted over the papers from 2020–2025.
Is Dual Nature of Matter and Radiation important for JEE Main 2027?
It is in the syllabus in force, so it can be asked. By past papers it ranks 16 of 20 in Physics; use that to decide how much time it gets, not whether to study it.
Where can I solve Dual Nature of Matter and Radiation JEE Main previous year questions?
On Nikaalle, free: sign up and practise every past JEE Main question from Dual Nature of Matter and Radiation with an explanation for each, or sit the full papers timed. The ten questions on this page are our own, written in the same pattern.
Your JEE Main 2027 plan, chapter by chapter.
A week-wise plan that gives the heavy chapters their time. Free, from a non-profit trust.