Skip to content

For Questions 13 to 16, two… (Class 12 Physics 2024, Q13)

questionbuddy.in/q/cbse-12-physics-2024-55-5-1-q13-labelled-other-labelled-equal-amount

PhysicsCBSE Class 12 · Board exam 2024, set 55/5/1 · 1 mark · Assertion-reason

CBSE Class 12 Physics 2024: question 13

Set in the CBSE Class 12 board exam of 2024, paper 55/5/1, section A, question 13, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q13 · 1 mark · Assertion-reasonCompetency-basedElectric Charges and Fields

For Questions 13 to 16, two statements are given – one labelled Assertion (A) and other labelled Reason (R).

Assertion (A): Equal amount of positive and negative charges are distributed uniformly on two halves of a thin circular ring as shown in figure. The resultant electric field at the centre O of the ring is along OC.

Reason (R): It is so because the net potential at O is not zero.

  1. (A)If both Assertion (A) and Reason (R) are true and Reason (R) is correct explanation of Assertion (A).
  2. (B)If both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A).
  3. (C)If Assertion (A) is true but Reason (R) is false.
  4. (D)If both Assertion (A) and Reason (R) are false.

Figure in the paper: Circular ring with centre O; points A (top), B (left), C (bottom), D (right) marked, with dashed diameters AC and BD. Upper half (A side, between B and D) carries + charges, lower half (C side) carries – charges. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 55/5/1.

Hints

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

Hint 1

Field points from positive towards negative charges.

Hint 2

Potential is a scalar: add contributions of +Q and −Q at equal distance.

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. Field of each element points away from + charges and towards − charges; horizontal components cancel by symmetry, vertical components add downward, so the net field at O is along OC. Assertion true.

    ½ mark

  2. Net potential at O = , so Reason is false. Option (C).

    ½ mark

Answer: Option (C)

Where the marks are

  • Assertion true (field along OC), Reason false (V = 0) (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 paper2024 board paper, set 55/5/1: 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.