The Alternating Current NCERT PDF below is the official 2026-27 NCERT textbook chapter for Class 12 Physics Chapter 7 Alternating Current, the resource you'll lean on for CBSE Boards (6 marks), JEE Main and NEET. Download the Alternating Current NCERT PDF once and treat it as your starting source for every numerical and derivation in this chapter.
- CBSE Weightage: 5 to 7 marks
- JEE Main Weightage: 3 to 4% (1 to 2 questions per paper)
- NEET Weightage: 2 to 3 questions per year
Both downloads of the Alternating Current NCERT PDF on this page are free and updated for the 2026-27 NCERT syllabus.
This page is curated by subject experts, mapped to the 2026-27 NCERT, and refined against the last five years of CBSE Board, JEE Main, and NEET papers.
Also Check:
- Alternating Current Class 12 Physics NCERT Solutions
- Alternating Current Class 12 Physics Notes
- Alternating Current Class 12 Physics Formula Sheet
How will the Alternating Current NCERT PDF on Collegedunia Help You?
The Collegedunia NCERT Book PDF page reproduces the official Chapter 7 file and adds navigation aids that the bare PDF lacks.
- 2026-27 NCERT Alignment: The PDF matches the current 2026-27 print of NCERT Physics Part I, with Sections 7.1 through 7.8 retained as in the 2023 edition.
- Section Map and Page Anchors: Each numbered section is tagged with its page range so you can jump to a derivation while solving Exercises.
- Expert Verification: Every Intext Example and Exercise count has been cross-checked against the official NCERT print.
- Multi-Pass Reading Plan: A short skim-then-solve sequence keeps the 30-page chapter under 4 hours of effective study.
Alternating Current Video Chapter Walkthrough
Source: NCERT Wallah on YouTube
What is Inside the Alternating Current NCERT Book PDF?
The PDF on this page matches what the NCERT server hosts. Several Exercises combine two sections and reward students who have read the chapter linearly rather than skipping to formula boxes.
Alternating Current NCERT Section-by-Section Breakdown for Class 12
The table below maps each section in Chapter 7 to its page range and core idea. Use it to locate a derivation before attempting an Exercise.
| Section | Title | Pages | Core Idea |
|---|---|---|---|
| 7.1 | Introduction | 1 | Why AC is preferred over DC for transmission and household supply |
| 7.2 | AC Voltage Applied to a Resistor | 2 to 4 | Instantaneous current, rms definition, average power formula |
| 7.3 | Phasors: Representation by Rotating Vectors | 5 to 6 | Phasor construction and phase-difference visualisation |
| 7.4 | AC Voltage Applied to an Inductor | 7 to 10 | Current lags by π/2 , inductive reactance XL = ω L |
| 7.5 | AC Voltage Applied to a Capacitor | 11 to 14 | Current leads by π/2 , capacitive reactance XC = 1/ω C |
| 7.6 | AC Voltage Applied to a Series LCR Circuit | 15 to 22 | Impedance, resonance, quality factor, bandwidth |
| 7.7 | Power in AC Circuit and Power Factor | 23 to 26 | Pavg = Vrms Irms cosφ , wattless current |
| 7.8 | Transformers | 27 to 30 | Turns ratio, step-up / step-down, real-world losses |
Section 7.6 takes up roughly a quarter of the chapter and feeds the bulk of board, JEE, and NEET questions.
Intext Example Inventory for Alternating Current Class 12th Physics
The chapter has 9 solved examples that escalate in difficulty. The list below indexes each Example to the sub-topic it tests.
| Example | Sub-topic Tested | Skill |
|---|---|---|
| 7.1 | Bulb resistance from rms current | RMS to peak conversion |
| 7.2 | Peak voltage from rms reading | Direct substitution |
| 7.3 | Inductor with AC source | Compute XL , find peak current |
| 7.4 | Capacitor with AC source | Compute XC , comment on power |
| 7.5 | Phasor solution for series LCR | Vector addition |
| 7.6 | Resonance frequency calculation | 0 = 1/√LC plug-in |
| 7.7 | Quality factor and sharpness | Q-factor interpretation |
| 7.8 | Average power and power factor | cosφ computation |
| 7.9 | Step-up transformer | Turns ratio, current scaling |
2026-27 NCERT Update Note for Alternating Current
The current 2026-27 print keeps Chapter 7 identical to the 2023 edition. Nothing was added, trimmed, or merged in this chapter for 2026-27. The list below summarises scope.
- Retained in full: Sections 7.1 through 7.8, including the phasor derivation of impedance, the Q-factor expression, and transformer energy-loss discussion.
- Removed in an earlier cycle (pre-2023): The standalone LC oscillations section. References inside the chapter remain qualitative only.
- Not in scope for 2026-27 Boards: Pure-numerical problems on LC oscillation period T = 2π√LC without an external source.
Students should not spend time on resonance-curve derivations beyond what Section 7.6 presents, as CBSE follows the Alternating Current NCERT PDF scope strictly.
How to Read the Alternating Current NCERT PDF (Pass-Sequence Plan)
A 30-page chapter looks short until the Exercises send you back to the derivations. The three-pass plan below keeps study time under 4 hours.
- Pass 1 (45 min) | Skim: Read Sections 7.1 to 7.3, glance at every diagram in 7.4 to 7.8, skip the algebra.
- Pass 2 (90 min) | Derive: Re-read 7.4, 7.5, 7.6 with a pen. Rederive XL , XC , and the LCR impedance. Solve Examples 7.3 to 7.7.
- Pass 3 (90 min) | Apply: Read 7.7 and 7.8 once, then attempt all 26 Exercises. Flag the ones combining resonance with transformer.
Chapter Weightage Bar Chart for Class 12 Physics
The visual below maps the typical CBSE Class 12 Physics marks distribution across all 14 chapters of the NCERT book, averaged over the last five board papers.
Comparison of Alternating Current with Other Boards (ICSE / State Equivalents)
The treatment of Alternating Current varies between school boards. The comparison below shows what overlaps with NCERT and what is unique to each board.
| Board / Textbook | Chapter Placement | Scope | Notable Difference vs NCERT |
|---|---|---|---|
| NCERT (CBSE) | Chapter 7, Part I | Sections 7.1 to 7.8 | Baseline reference |
| ICSE (ISC Class 12 Physics) | Section E, Unit 6 | AC, LCR, resonance, transformer | Includes choke coil and AC generator in more detail; resonance treated graphically |
| Maharashtra State Board | Chapter 13 | AC, LCR, power, resonance | Transformer covered in a separate chapter; LC oscillations retained |
| Tamil Nadu State Board | Volume 1, Unit 4 | AC, phasors, LCR, transformer | Includes wattmeter and rotating-field motor introduction |
| Karnataka PUC II | Chapter 7 (follows NCERT) | Identical to NCERT | None of significance; same numbering, same Exercises |
NCERT keeps the chapter the lightest. State-board students often find the JEE Main version of an LCR question harder than their own board, because JEE assesses AC generators and choke coils numerically while NCERT does not.
Alternating Current Previous Year Question Trends from the NCERT Chapter
The three trends below summarise where CBSE, JEE, and NEET have pulled questions from this NCERT chapter over the last three years.
| Trend | Where Tested | NCERT Section |
|---|---|---|
| Series LCR with resonance and Q-factor numerical | CBSE 2025, JEE Main 2025 | Sec 7.6 |
| Transformer step-up / step-down and efficiency | CBSE 2024, NEET 2024 | Sec 7.8 |
| Phasor diagram interpretation MCQ | JEE Main 2024, CBSE 2023 | Sec 7.3, 7.6 |
Full year-wise PYQ map (2021 to 2026): Alternating Current Class 12 Physics NCERT Solutions
Top 5 Alternating Current Formulae from the NCERT Chapter
These five relations cover roughly 80 percent of the Exercises in the chapter.
| Quantity | Formula | NCERT Section |
|---|---|---|
| RMS voltage | Vrms = V0 / √2 | 7.2 |
| Inductive reactance | XL = ω L = 2π f L | 7.4 |
| Capacitive reactance | XC = 1/ω C | 7.5 |
| Series LCR impedance | Z = √R2 + XL - XC2 | 7.6 |
| Resonance frequency | 0 = 1/√LC | 7.6 |
Full master table: Alternating Current Class 12 Physics Formula Sheet
Related Links:
More Alternating Current Physics Class 12 Resources
NCERT Book PDF for Class 12 Physics: All Chapters
Other Class 12 Physics NCERT Book PDFs you can grab as free downloads:
| Chapter | Resource |
|---|---|
| Chapter 1 | Electric Charges and Fields NCERT PDF |
| Chapter 2 | Electrostatic Potential and Capacitance NCERT PDF |
| Chapter 3 | Current Electricity NCERT PDF |
| Chapter 4 | Moving Charges and Magnetism NCERT PDF |
| Chapter 5 | Magnetism and Matter NCERT PDF |
| Chapter 6 | Electromagnetic Induction NCERT PDF |
| Chapter 8 | Electromagnetic Waves NCERT PDF |
| Chapter 9 | Ray Optics and Optical Instruments NCERT PDF |
| Chapter 10 | Wave Optics NCERT PDF |
| Chapter 11 | Dual Nature of Radiation and Matter NCERT PDF |
| Chapter 12 | Atoms NCERT PDF |
| Chapter 13 | Nuclei NCERT PDF |
| Chapter 14 | Semiconductor Electronics NCERT PDF |
Alternating Current NCERT PDF: available above as a free PDF download, fully aligned to the 2026-27 NCERT release.
Alternating Current NCERT PDF - Frequently Asked Questions
Ques. Where can I download the Alternating Current NCERT PDF for free?
Ans. You can download the Alternating Current NCERT PDF directly from this page. Both the Normal and HD versions are available, and both are free. The PDF is the official chapter file released by NCERT for the 2026-27 session.
Ques. Is this Alternating Current NCERT PDF aligned with the 2026-27 CBSE syllabus?
Ans. Yes. This page reflects the current 2026-27 syllabus for Class 12 Physics. Chapter 7 is identical to the 2023 edition, so all eight sections from 7.1 Introduction to 7.8 Transformers remain part of the prescribed reading.
Ques. How many pages is the Class 12th Physics Alternating Current NCERT Book PDF?
Ans. The Chapter 7 NCERT Book PDF runs to approximately 30 pages and covers eight sections, 9 solved examples, and 26 end-of-chapter Exercises. The bulk of the Alternating Current NCERT PDF is taken up by Section 7.6 on series LCR and Section 7.8 on transformers.
Ques. How many marks does Alternating Current carry in CBSE Class 12 Physics?
Ans. Chapter 7 contributes 5 to 7 marks in the CBSE Class 12 Physics board paper. Marks are usually split across a 3-mark LCR or resonance numerical and a 2 to 3 mark transformer or power-factor question. The chapter is part of Unit 4 along with Electromagnetic Induction.
Ques. What is the JEE Main and NEET weightage of Alternating Current from the NCERT chapter?
Ans. JEE Main typically draws 3 to 4 percent of its Physics paper from Alternating Current NCERT PDF, which works out to 1 or 2 questions per shift, mostly on series LCR and resonance. NEET asks 2 to 3 questions a year from this chapter, with the most common topic being reactance comparison and transformer turns ratio.
Ques. Which sections of the NCERT chapter are the most important for CBSE Boards?
Ans. Sections 7.6 (Series LCR), 7.7 (Power Factor) and 7.8 (Transformer) carry the bulk of the marks. CBSE almost always asks a 3-mark numerical or derivation from 7.6, a 2-mark short-answer from 7.7 and either a numerical or a working-principle question from 7.8.
Ques. Was anything removed from Chapter 7 in the latest NCERT edition?
Ans. No content was removed from Chapter 7 in the latest NCERT print. Earlier edits had trimmed the standalone treatment of LC oscillations, but Sections 7.1 to 7.8 of the current chapter are all in scope for 2026-27 Boards, JEE Main and NEET.
Ques. How many Examples and Exercises does the NCERT Alternating Current chapter contain?
Ans. The chapter contains approximately 9 solved intext Examples spread across Sections 7.2 to 7.8, plus 26 Exercises at the end of the chapter. Several Exercises combine series LCR analysis with power-factor or transformer reasoning into a single multi-part question.
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