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State Gauss’s law of… (Class 12 Physics SQP 2026-27, Q20B)

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PhysicsCBSE Class 12 · Sample paper, session 2026-27 · 2 marks · Very short answer

CBSE Class 12 Physics sample paper 2026-27: question 20(B)

From the official CBSE sample question paper for 2026-27, section B, question 20(B), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q20(B) · 2 marks · Very short answerMagnetism and Matter

State Gauss’s law of magnetism. Also discuss its significance.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2026-27.

Hints

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

Hint 1

Compare with Gauss's law in electrostatics — what would be the 'enclosed magnetic charge'?

Hint 2

If flux is zero, what does that say about field lines entering and leaving a surface?

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. Gauss's law of magnetism: the net magnetic flux through any closed surface is always zero: .

    1 mark

  2. Significance 1: Isolated magnetic poles (magnetic monopoles) do not exist; poles always occur in pairs.

    ½ mark

  3. Significance 2: Magnetic field lines form continuous closed loops — as many lines enter a closed surface as leave it; they neither start nor end anywhere.

    ½ mark

Answer: ∮B·dS = 0; monopoles do not exist and field lines form closed loops.

Where the marks are

  • Correct statement with (1 mark)
  • Monopoles do not exist (½ mark)
  • Field lines form closed loops (½ mark)

Revise the chapter

Practise this chapterBoard-style questions from Magnetism and Matter, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2026-27: 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.