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A uniform magnetic field… (Class 10 Science 2024, Q15)

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ScienceCBSE Class 10 · Board exam 2024, set 31/5/1 · 1 mark · MCQ

CBSE Class 10 Science 2024: question 15

Set in the CBSE Class 10 board exam of 2024, paper 31/5/1, section A, question 15, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q15 · 1 mark · MCQMagnetic Effects of Electric Current

A uniform magnetic field exists in the plane of paper as shown in the diagram. In this field, an electron () and a positron () enter as shown. The electron and positron experience forces:

  1. (A)both pointing into the plane of the paper.
  2. (B)both pointing out of the plane of the paper.
  3. (C)pointing into the plane of the paper and out of the plane of the paper respectively.
  4. (D)pointing out of the plane of the paper and into the plane of the paper respectively.

Figure in the paper: Three horizontal parallel arrows pointing right labelled 'Uniform magnetic field' (field lies in the plane of the paper). Two vertical lines cross the field lines: on the left, a dot labelled e with the vertical line carrying an arrowhead pointing downward; on the right, a dot labelled p with the vertical line carrying an arrowhead pointing upward. Both particles move perpendicular to the field. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 31/5/1.

Hints

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

Hint 1

Treat each moving charge as a current; an electron's current is opposite to its motion.

Hint 2

Apply Fleming's left-hand rule.

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. An electron moving down is equivalent to a conventional current pointing up, which is the same as the positron moving up.

  2. For an upward current in a field to the right, Fleming's left-hand rule gives a force into the paper for both particles. Option (A).

    1 mark

Answer: Option (A)

Where the marks are

  • Chooses (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 paper2024 board paper, set 31/5/1: 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.