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If the phasor diagram… (Class 12 Physics SQP 2025-26, Q3)

questionbuddy.in/q/cbse-12-physics-2025-26-sqp-q3-phasor-diagram-device-connected-supply

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

CBSE Class 12 Physics sample paper 2025-26: question 3

From the official CBSE sample question paper for 2025-26, section A, question 3, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q3 · 1 mark · MCQAlternating Current

If the phasor diagram for a device connected to AC supply is as shown in the fig, then which of the following statements is true?

  1. (A)When the frequency of the AC source is increased than the impedance of the device decreases.
  2. (B)This device behaves as conducting wire when connected across DC source.
  3. (C)When the frequency of the AC source is decreased than the impedance of the device decreases.
  4. (D)This device stores energy in the form of magnetic potential energy.

Figure in the paper: Phasor diagram with perpendicular phasors: V pointing up-left (blue) and I pointing down-left (grey), with a right-angle mark between them at the origin. See it in the official paper.

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

Which phasor is ahead in the anticlockwise sense?

Hint 2

Which element has current leading voltage by 90°, and how does its reactance vary with frequency?

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. From the phasor diagram, the current leads the voltage by , so the device is a pure capacitor.

  2. Its reactance is , so the impedance decreases as the frequency increases. Option (A).

    1 mark

Answer: Option (A)

Where the marks are

  • Identifies the device as a capacitor (current leads by 90°) and uses (1 mark)

Revise the chapter

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.

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.