Alternating Current: The Exact Questions RBSE Keeps Asking (Chapter 7)

If you have gone through the last decade of RBSE Class 12 Physics papers, you will notice Chapter 7 (Alternating Current) is tested every year without fail. It belongs to Unit IV — Electromagnetic Induction and Alternating Currents and is drawn from a pool of 32 previous-year questions spanning 2013–2026, spread across MCQs, very short, short and long-answer sections. The topics rotate, but the question patterns stay remarkably steady.

Expect 0.5 to 1-mark openers on rms/peak value relations and phase-angle basics. The 2 to 3-mark questions lean on transformer turns-ratio problems and power-factor calculations. The heavy marks sit in the 4-mark long answers, which rotate between deriving the AC generator's instantaneous emf, the impedance of a series LCR circuit, and resonance in an LCR circuit — this chapter has 32 questions in the full pool, so no single question repeats often, but these three derivations recur in some form nearly every year.

So the smart way to revise this chapter is not to read it end to end, but to practise the questions RBSE actually repeats. The five questions above — and the ten in the free sample PDF — are taken straight from real board papers and tagged with the exact years they appeared, so you can see for yourself what the full RBSE Physics chapterwise PYQ book offers before you decide to buy it.