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Friday, 9 October

NEET UG 2021 · Physics · Question 26

NEET 2021 Physics, question 26

Question 26 of the NEET 2021 paper (code O1) is a Physics question from Dual Nature of Radiation and Matter. Its idea, De Broglie Wavelength of Emitted Photoelectron, was asked only this once in NEET 2017–2026. The NTA final answer key gives option 1.

Updated 2026-10-08

Q26 · Physics

An electromagnetic wave of wavelength 'λ\lambda' is incident on a photosensitive surface of negligible work function. If 'm' mass is of photoelectron emitted from the surface has de-Broglie wavelength λd\lambda_d, then :

  1. 1λ=(2mch)λd2\lambda = \left(\frac{2mc}{h}\right)\lambda_d^{2}Official answer
  2. 2λ=(2hmc)λd2\lambda = \left(\frac{2h}{mc}\right)\lambda_d^{2}
  3. 3λ=(2mhc)λd2\lambda = \left(\frac{2m}{hc}\right)\lambda_d^{2}
  4. 4λd=(2mch)λ2\lambda_d = \left(\frac{2mc}{h}\right)\lambda^{2}

Official answer: option 1 · NTA final answer key

Same idea

The only question on De Broglie Wavelength of Emitted Photoelectron

No other NEET paper from 2017–2026 tested this exact idea.

De Broglie Wavelength of Emitted Photoelectron: every question and how it was framed

The chapter

Dual Nature of Radiation and Matter in ten years of NEET

20 questions from 2017–2026, asked in 10 of 10 papers, about 1.9 a paper. Photoelectric Effect alone had 20.

Chapter analysisStudy this chapterPractise this chapter

Dual Nature of Radiation and Matter: questions per paper

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