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Photoemission of electrons… (Class 12 Physics 2026, Q27)

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PhysicsCBSE Class 12 · Board exam 2026, set 55/5/1 · 3 marks · Short answer

CBSE Class 12 Physics 2026: question 27

Set in the CBSE Class 12 board exam of 2026, paper 55/5/1, section C, question 27, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q27 · 3 marks · Short answerDual Nature of Radiation and Matter

Photoemission of electrons occurs from a metal ( eV) when light of frequency Hz is incident on it. Calculate :
(a) Energy of a photon in the incident light,
(b) The maximum kinetic energy of the emitted electrons, and
(c) The stopping potential.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 55/5/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Photon energy E = hν; convert joules to eV by dividing by 1.6 × 10⁻¹⁹.

Hint 2

Use Einstein's photoelectric equation, and eV₀ = K_max.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. (a) J eV

    1 mark

  2. (b) Einstein's equation: eV J)

    1 mark

  3. (c) V

    1 mark

Answer: (a) 4.24 × 10^-19 J ≈ 2.65 eV; (b) 0.69 eV; (c) 0.69 V

Where the marks are

  • Photon energy hν ≈ 2.65 eV (1 mark)
  • K_max = hν − φ₀ = 0.69 eV (1 mark)
  • Stopping potential 0.69 V (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Dual Nature of Radiation and Matter, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 55/5/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.