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Assertion (A) : The strength… (Class 10 Science 2023, Q20)

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ScienceCBSE Class 10 · Board exam 2023, set 31/1/1 · 1 mark · Assertion-reason

CBSE Class 10 Science 2023: question 20

Set in the CBSE Class 10 board exam of 2023, paper 31/1/1, section A, question 20, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q20 · 1 mark · Assertion-reasonCompetency-basedMagnetic Effects of Electric Current

Assertion (A) : The strength of the magnetic field produced at the centre of a current carrying circular coil increases on increasing the number of turns in it.
Reason (R) : The current in each circular turn has the same direction and the magnetic field due to each turn then just adds up.

  1. (A)Both (A) and (R) are true and (R) is the correct explanation of (A).
  2. (B)Both (A) and (R) are true, but (R) is not the correct explanation of (A).
  3. (C)(A) is true, but (R) is false.
  4. (D)(A) is false, but (R) is true.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/1/1.

Hints

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

Hint 1

How does the field at the centre depend on the number of turns?

Hint 2

Do the fields from the separate turns add or cancel?

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. For a coil of n turns, the field at the centre is n times the field of a single turn. So (A) is true.

  2. This happens because the current flows in the same direction in every turn, so the fields add up. (R) is true and explains (A), option (A).

    1 mark

Answer: Option (A)

Where the marks are

  • Both true and R correctly explains A (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Magnetic Effects of Electric Current, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 31/1/1: 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.