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On the basis of the given… (Class 10 Science 2026, Q37)

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ScienceCBSE Class 10 · Board exam 2026, set 31/4/1 · 3 marks · Short answer

CBSE Class 10 Science 2026: question 37

Set in the CBSE Class 10 board exam of 2026, paper 31/4/1, section C, question 37, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q37 · 3 marks · Short answerCompetency-basedMagnetic Effects of Electric Current

On the basis of the given circuit arrangement, answer the following questions:
(a) What happens to the rod AB when the key K is closed and why?
(b) Name and state the rule that determines this behaviour of the rod AB in the above situation.

Figure in the paper: A horseshoe magnet with N and S poles, with a rod AB (a straight conductor suspended horizontally between the magnet's poles from a stand, connected via flexible leads) placed between the poles. A battery (marked + and -) in series with a key K completes the circuit through the rod AB. Current direction in the rod is marked by an arrow from A to B, and the magnetic field lines of the horseshoe magnet are shown between the poles. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/4/1.

Hints

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

Hint 1

What happens to a current-carrying wire placed in a magnetic field?

Hint 2

The force is perpendicular to both the current and the field.

Hint 3

There is a 'hand rule' that uses three mutually perpendicular fingers of one hand.

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) When key K is closed, current flows through rod AB and the rod gets displaced (moves) from its original position.

    ½ mark

  2. This happens because a current-carrying conductor placed in a magnetic field experiences a force. The force acts perpendicular to both the current and the field.

    ½ mark

  3. (b) The direction of this force is given by Fleming's Left-Hand Rule.

    1 mark

  4. Statement: stretch the thumb, forefinger and middle finger of the left hand so that they are mutually perpendicular. If the forefinger points along the magnetic field and the middle finger along the current, then the thumb points in the direction of the force (motion) on the conductor.

    1 mark

Answer: (a) Rod AB is displaced because a current-carrying conductor in a magnetic field experiences a force. (b) Fleming's Left-Hand Rule, as stated.

Where the marks are

  • Rod AB gets displaced (½ mark)
  • Reason: force on current-carrying conductor in magnetic field (½ mark)
  • Names Fleming's Left-Hand Rule (1 mark)
  • Correct statement of the rule (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 paper2026 board paper, set 31/4/1: 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.