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Identify the circuit… (Class 12 Physics SQP 2024-25, Q22I)

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PhysicsCBSE Class 12 · Sample paper, session 2024-25 · 3 marks · Short answer

CBSE Class 12 Physics sample paper 2024-25: question 22(I)

From the official CBSE sample question paper for 2024-25, section C, question 22(I), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q22(I) · 3 marks · Short answerSemiconductor Electronics: Materials, Devices and Simple Circuits

Identify the circuit elements X and Y as shown in the given block diagram and draw the output waveforms of X and Y.

Figure in the paper: Block diagram: AC source connected to block X, then block Y, then a D.C. Appliance. See it in the official paper.

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

A dc appliance needs steady dc, but the source is ac. What two jobs must be done in between?

Hint 2

The first stage makes the current flow one way only; the second smooths out its fluctuations.

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. X is a rectifier (p-n junction diode circuit). It converts the alternating input into unidirectional (pulsating) current.

    ½ mark

  2. Y is a filter circuit (e.g. a capacitor across the load). It removes the ac ripple and gives a nearly steady dc for the appliance.

    ½ mark

  3. Output waveform of X (full-wave rectifier): a series of positive half-sine humps, one per half cycle, all above the time axis. The voltage rises from zero to the peak and falls back to zero each half cycle. (For a half-wave rectifier, alternate humps are missing.)

    1 mark

  4. Output waveform of Y: a nearly flat line at about the peak value. The capacitor charges up to the peak and discharges slightly between humps, giving a small saw-tooth ripple on a steady dc level.

    1 mark

Answer: X = rectifier (output: pulsating unidirectional dc); Y = filter (output: nearly steady dc with small ripple)

Where the marks are

  • Identifies X as a rectifier (½ mark)
  • Identifies Y as a filter (½ mark)
  • Correct pulsating-dc waveform for X (1 mark)
  • Correct smoothed dc waveform with small ripple for Y (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Semiconductor Electronics: Materials, Devices and Simple Circuits, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2024-25: 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.