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Assertion (A): For the… (Class 12 Physics SQP 2023-24, Q13)

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PhysicsCBSE Class 12 · Sample paper, session 2023-24 · 1 mark · Assertion-reason

CBSE Class 12 Physics sample paper 2023-24: question 13

From the official CBSE sample question paper for 2023-24, section A, question 13, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q13 · 1 mark · Assertion-reasonCompetency-basedDual Nature of Radiation and Matter

Assertion (A): For the radiation of a frequency greater than the threshold frequency, photoelectric current is proportional to the intensity of the radiation.
Reason (R): Greater the number of energy quanta available, greater is the number of electrons absorbing the energy quanta and greater is number of electrons coming out of the metal.

  1. (A)If both Assertion and Reason are true and Reason is correct explanation of Assertion.
  2. (B)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
  3. (C)If Assertion is true but Reason is false.
  4. (D)If both Assertion and Reason are false.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2023-24.

Hints

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

Hint 1

What does intensity mean in the photon picture?

Hint 2

Each photon can eject at most one electron.

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. Above threshold, higher intensity means more photons per second, so more electrons are emitted and photocurrent ∝ intensity: A is true.

    ½ mark

  2. R states exactly this photon picture, so it correctly explains A.

    ½ mark

Answer: Option (A)

Where the marks are

  • Both true, R explains A (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 paperSample paper 2023-24: 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.