NCERT Class 12 Physics Chapter 7 Alternating Current Solutions were updated on Apr 17, 2026 . This chapter carries around 4–7 marks in CBSE boards and contributes 3–6% in JEE/NEET and 12–14% in CUET, so you should prioritise it in your revision.
NCERT Class 12 Physics Chapter 7 Alternating Current Solutions — What to focus on
Key topics to master: phasor diagrams, power factor, LCR circuit, resonance, transformers, RMS/peak values, impedance and reactance. Phasor diagrams and power-factor numericals appear almost every year, so practice them till you’re fast and accurate.
Expect exam-style coverage: about 6–7 questions worth 7–9 marks in board papers, and roughly 1–2 JEE Main questions per shift . CUET typically allocates around 3–4 marks to this unit.
NCERT Class 12 Physics Chapter 7 Alternating Current Solutions — Study time & plan
Recommended total study time is 8–10 hours including revision. An alternate estimate used by many students is 6–8 hours for first completion.
| Task | Suggested time |
|---|---|
| Derivations and core concepts | 4 h |
| Practice numericals | 3 h |
| Phasor diagrams | 1 h |
| Revision & formula recap | 1–2 h |
Study this chapter alongside Electromagnetic Induction for cohesion; combined study can extend total time to 10–12 hours .
How the solutions help you (what they include)
Solutions provide step-by-step NCERT question explanations, full intermediate calculations, and diagrams. They cover important derivations: phase differences for pure L/C, impedance and phase in series LCR, resonance condition (ω0 = 1/√LC), average power and transformer ratios.
Follow this approach for numericals: note given values, identify circuit type, draw phasor diagram, list formulas, compute with units, and box the final answer. This reduces careless mistakes on peak vs rms and power-factor calculations.
Exam pattern snapshot
| Exam | Typical contribution |
|---|---|
| CBSE Boards | 4–7 marks (7–9 if combined with EMI) |
| JEE Main | 1–2 questions per shift (numerical focus) |
| NEET | ~ 2 questions (theory + application) |
| CUET | 3–4 marks (LCR, transformers, resonance) |
Coverage gaps in available materials
No direct PDF download link, no topic-wise practice tests, and no interactive phasor tools are included in the standard solution packs. You should attempt NCERT examples first and then use the solution steps to clear doubts.
FAQs
Is Chapter 7 Alternating Current important for CBSE Class 12 board exams 2026?
Yes. It carries around 4–7 marks and 7–9 marks if combined with Electromagnetic Induction.
What are the most important topics in this chapter?
Phasor diagrams, power factor, LCR circuit, resonance, transformers, impedance, RMS/peak values and average power.
Which derivations should I memorise?
Phase difference in pure L/C, impedance and phase in series LCR, resonance frequency (ω0 = 1/√LC), average power, and transformer voltage/current ratios.
How many hours should I spend on this chapter?
Recommended 8–10 hours total; alternate realistic completion time 6–8 hours .
Are phasor diagram and power-factor numericals frequent in exams?
Yes. Phasor and power-factor numericals are asked almost yearly across boards and competitive exams.
Should I study this chapter with Electromagnetic Induction?
Yes. Studying both together improves concept linkage and can change total study time to 10–12 hours .
(Article updated Apr 17, 2026 .)