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Answer the following. (Science 2023 31/1/1 Q32a)

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ScienceCBSE Class 10 · Board exam 2023, set 31/1/1 · 3 marks · Short answer

CBSE Class 10 Science 2023: question 32(a)

Set in the CBSE Class 10 board exam of 2023, paper 31/1/1, section C, question 32(a), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q32(a) · 3 marks · Short answerMagnetic Effects of Electric Current

Answer the following.

  1. (i)

    State the rule used to find the force acting on a current carrying conductor placed in a magnetic field.

    0 marks
  2. (ii)

    Given below are three diagrams showing entry of an electron in a magnetic field. Identify the case in which the force will be (1) maximum and (2) minimum respectively. Give reason for your answer.

    0 marks

Figure in the paper: Three diagrams, each with horizontal parallel magnetic field lines pointing right (labelled Magnetic field). (i) Electron path is vertical, perpendicular to the field, pointing up. (ii) Electron path is inclined obliquely across the field lines. (iii) Electron moves horizontally, parallel to the field, in the same direction. See it in the official paper.

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

The rule uses three mutually perpendicular fingers of one hand. Which hand is used for motors?

Hint 2

The force depends on the angle between the direction of motion and the field. When is it greatest, and when is it zero?

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. (i) Fleming's left-hand rule: Stretch the thumb, forefinger and middle (central) finger of the left hand so that they are mutually perpendicular.

    • If the forefinger points in the direction of the magnetic field,
    • and the middle finger points in the direction of the current,
    • then the thumb gives the direction of the force (motion) on the conductor.
    1 mark

  2. (ii)(1) The force is maximum in Fig. (i).

    ½ mark

  3. Reason: the electron moves at right angles (perpendicular) to the magnetic field, and the force is greatest when the motion is perpendicular to the field.

    ½ mark

  4. (ii)(2) The force is minimum (zero) in Fig. (iii).

    ½ mark

  5. Reason: the electron moves along (parallel to) the magnetic field lines, and no force acts when the motion is parallel to the field.

    ½ mark

Answer: (i) Fleming's left-hand rule; (ii) (1) maximum in Fig. (i), since the motion is perpendicular to the field; (2) minimum (zero) in Fig. (iii), since the motion is parallel to the field.

Where the marks are

  • Correct statement of Fleming's left-hand rule (1 mark)
  • Identifies Fig. (i) for maximum force (½ mark)
  • Reason: perpendicular to the field (½ mark)
  • Identifies Fig. (iii) for minimum force (½ mark)
  • Reason: parallel to the field (½ 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.