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Two horizontal plates… (Class 12 Physics 2025, Q1)

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PhysicsCBSE Class 12 · Board exam 2025, set 55/7/1 · 1 mark · MCQ

CBSE Class 12 Physics 2025: question 1

Set in the CBSE Class 12 board exam of 2025, paper 55/7/1, section A, question 1, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q1 · 1 mark · MCQElectric Charges and Fields

Two horizontal plates, separated by 1 cm, are arranged one above the other. A particle of mass 5 mg and charge 2 nC is released in air between the plates. The potential difference that should be applied to the plates so that the particle remains suspended between them, is :

  1. (A)250 V
  2. (B)200 V
  3. (C)100 V
  4. (D)50 V

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 55/7/1.

Hints

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

Hint 1

What two forces act on the suspended particle?

Hint 2

Set with , and convert mg to kg and nC to C.

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 the particle to stay suspended, the electric force balances its weight: with , so .

    ½ mark

  2. ½ mark

Answer: 250 V, option (A)

Where the marks are

  • Uses and gets 250 V (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Electric Charges and Fields, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 55/7/1: 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.