PhysicsCBSE Class 12 · Sample paper, session 2025-26 · 3 marks · Short answer

CBSE Class 12 Physics sample paper 2025-26: question 27(II)

From the official CBSE sample question paper for 2025-26, section C, question 27(II), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q27(II) · 3 marks · Short answerMagnetism and Matter

A solenoid has a core of material with relative permeability 200. The windings of the solenoid are insulated from the core and carry a current of 1A. If the number of turns is 2000 per metre, calculate
(A) magnetic intensity,
(B) magnetic field &
(C) magnetisation

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2025-26.

Hints

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

Hint 1

H inside a solenoid depends only on turns per metre and current.

Hint 2

Use $B = μ_{0} μ_{r} H$ and $M = (μ_{r} - 1) H$ .

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.

(A) Magnetic intensity $H = n I = 2000 \times 1 = 2 \times 1 0^{3}$ A/m
1 mark
(B) $B = μ_{0} μ_{r} H = 4 π \times 1 0^{- 7} \times 200 \times 2 \times 1 0^{3} = 0.16 π \approx 0.50$ T
1 mark
(C) Magnetisation $M = χH = (μ_{r} - 1) H = 199 \times 2 \times 1 0^{3} = 3.98 \times 1 0^{5}$ A/m
1 mark

Answer: (A) 2×10³ A/m; (B) ≈ 0.50 T; (C) 3.98×10⁵ A/m

Where the marks are

H = nI = 2×10³ A/m (1 mark)
B = μ₀μᵣH ≈ 0.50 T (1 mark)
M = (μᵣ − 1)H = 3.98×10⁵ A/m (1 mark)

Revise the chapter

Chapter: Magnetism and Matter (notes, formulas, where marks are lost and every past question)
Topic: Magnetisation and Magnetic Intensity

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 2025-26: every question, by section.

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CBSE Class 12 Physics sample paper 2025-26: question 27(II)

Hints

Step-by-step solution

Revise the chapter

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