PhysicsCBSE Class 12 · Sample paper, session 2025-26 · 1 mark · MCQ

CBSE Class 12 Physics sample paper 2025-26: question 10

From the official CBSE sample question paper for 2025-26, section A, question 10, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q10 · 1 mark · MCQAlternating Current

The emf generated by an AC generator is given by $V = V_{o} sin ω t$ , where ω is angular frequency of armature of generator. What will be the emf if the angular frequency is doubled

(A) $V = V_{o} sin 2 ω t$
(B) $V = 2 V_{o} sin ω t$
(C) $V = 2 V_{o} sin 2 ω t$
(D) $V = V_{o} sin ω t$

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2025-26.

Hints

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

Hint 1

Write the full expression for a generator's emf.

Hint 2

Where does $ω$ appear in that expression?

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.

The generator emf is $V = N B A ω sin ω t$ , so the peak value is $V_{0} = N B A ω$ .
Doubling $ω$ doubles both the peak and the argument: $V = 2 V_{0} sin 2 ω t$ . Option (C).
1 mark

Answer: $V = 2 V_{0} sin 2 ω t$ , option (C)

Where the marks are

Recognises that the amplitude is proportional to $ω$ (1 mark)

Revise the chapter

Chapter: Alternating Current (notes, formulas, where marks are lost and every past question)

Practise this chapterBoard-style questions from Alternating Current, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2025-26: every question, by section.

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CBSE Class 12 Physics sample paper 2025-26: question 10

Hints

Step-by-step solution

Revise the chapter

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