PhysicsCBSE Class 12 · Sample paper, session 2024-25 · 1 mark · MCQ

CBSE Class 12 Physics sample paper 2024-25: question 5

From the official CBSE sample question paper for 2024-25, section A, question 5, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q5 · 1 mark · MCQElectromagnetic Waves

A capacitor consists of two parallel plates, with an area of cross-section of 0.001 m $^{2}$ , separated by a distance of 0.0001 m. If the voltage across the plates varies at the rate of $1 0^{8}$ V/s, then the value of displacement current through the capacitor is

(A) $8.85 \times 1 0^{- 3}$ A
(B) $8.85 \times 1 0^{- 4}$ A
(C) $7.85 \times 1 0^{- 3}$ A
(D) $9.85 \times 1 0^{- 3}$ A

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2024-25.

Hints

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

Hint 1

Displacement current equals $C d V / d t$ .

Hint 2

Find C from $ε_{0} A / d$ .

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.

Capacitance: $C = \frac{ε _{0} A}{d} = \frac{8.85 \times 1 0 ^{- 12} \times 1 0 ^{- 3}}{1 0 ^{- 4}} = 8.85 \times 1 0^{- 11}$ F.
½ mark
Displacement current: $I_{d} = C \frac{d V}{d t} = 8.85 \times 1 0^{- 11} \times 1 0^{8} = 8.85 \times 1 0^{- 3}$ A. The answer is (A).
½ mark

Answer: $8.85 \times 1 0^{- 3}$ A, option (A)

Where the marks are

Finds $C$ (0.5 mark)
$I_{d} = C d V / d t$ (0.5 mark)

Revise the chapter

Chapter: Electromagnetic Waves (notes, formulas, where marks are lost and every past question)
Topic: Displacement Current

Practise this chapterBoard-style questions from Electromagnetic Waves, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2024-25: every question, by section.

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CBSE Class 12 Physics sample paper 2024-25: question 5

Hints

Step-by-step solution

Revise the chapter

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