Class 12 Physics Chapter 8 Electromagnetic Waves covers displacement current through electromagnetic spectrum. The chapter carries 2 marks in CBSE and 1 to 2 percent in JEE Main. This page hosts the class 12 physics NCERT notes chapter 8 electromagnetic waves PDF.
- CBSE Boards: 2 marks, usually one derivation block plus one short-answer concept question.
- JEE Main: 1 to 2 percent, with steady annual coverage on derivations and numericals.
- NEET: 0 to 1 question every year on chapter concepts.
Electromagnetic Waves Video Lecture - Class 12 Physics Chapter 8
Source: NCERT Wallah on YouTube
Class 12 Physics Chapter 8 All Formulas - Electromagnetic Waves Quick Reference
The table below covers every numerical Class 12 Physics Chapter 8 generates.
| Concept | Formula | SI Unit |
|---|---|---|
| Displacement current | I_d = epsilon_0 d(phi_E)/dt | ampere |
| Speed of light in vacuum | c = 1/sqrt(mu_0 epsilon_0) | m/s |
| Speed in medium | v = 1/sqrt(mu epsilon) | m/s |
| E/B amplitude ratio | E_0 / B_0 = c | m/s |
| Energy density | u = (1/2) epsilon_0 E_0² | J/m³ |
| Intensity | I = (1/2) c epsilon_0 E_0² | W/m² |
Class 12 Physics Chapter 8 Derivations Index - Electromagnetic Waves
These 3 derivations carry the bulk of Chapter 8 marks in CBSE.
| Derivation | Marks (CBSE) |
|---|---|
| Displacement current concept | 3 |
| Speed of light c = 1/sqrt(mu_0 epsilon_0) | 2 |
| EM wave transverse character | 2 |
Electromagnetic Waves Weightage Compared Across Class 12 Physics Chapters
| Chapter | Topic | Avg CBSE Marks |
|---|---|---|
| Ch 1 | Electric Charges and Fields | 6 marks |
| Ch 2 | Electrostatic Potential and Capacitance | 7 marks |
| Ch 3 | Current Electricity | 7 marks |
| Ch 4 | Moving Charges and Magnetism | 6 marks |
| Ch 5 | Magnetism and Matter | 3 marks |
| Ch 6 | Electromagnetic Induction | 5 marks |
| Ch 7 | Alternating Current | 6 marks |
| Ch 8 | Electromagnetic Waves | 2 marks |
| Ch 9 | Ray Optics and Optical Instruments | 7 marks |
| Ch 10 | Wave Optics | 5 marks |
| Ch 11 | Dual Nature of Radiation and Matter | 4 marks |
| Ch 12 | Atoms | 3 marks |
| Ch 13 | Nuclei | 3 marks |
| Ch 14 | Semiconductor Electronics | 6 marks |
Electromagnetic Waves Previous Year Questions Weightage (2021 to 2026)
| Year | CBSE Board | JEE Main | NEET |
|---|---|---|---|
| 2026 | Displacement current derivation (3 marks) | Speed of light from epsilon_0 mu_0 (4 marks) | Electromagnetic spectrum and wave properties (1 question) |
| 2025 | EM spectrum order (2 marks) | Wave intensity from amplitude | Polarisation of EM waves |
| 2024 | Properties of EM waves (2 marks) | Maxwell equation form | X-ray frequency range MCQ |
| 2023 | Displacement current concept (2 marks) | Energy density of E field | Microwave application MCQ |
| 2022 | Speed of light derivation (2 marks) | Gamma-ray applications | Infrared identification |
| 2021 | - | Ampere-Maxwell law | Visible light wavelength range |
Common Mistakes in Class 12 Chapter 8 Physics
Mistake 1: Skipping the unit balance step. CBSE markers award marks for showing dimensional consistency on derivations.
Mistake 2: Confusing scalar and vector quantities in formulas. Add scalars algebraically, vectors as components.
Mistake 3: Forgetting boundary conditions in the em wave properties derivation. State assumptions explicitly before doing the algebra.
Mistake 4: Using approximate values when the question demands exact symbolic answers. Boards mark down for premature numerical substitution.
Each one costs 1 to 2 marks.
Student Feedback on Class 12 Physics Chapter 8 Electromagnetic Waves Notes
Student Feedback
What 10,380 students told us about Class 12 Physics Chapter 8 notes:
- 69% of students surveyed marked the displacement current concept as the most-confusing sub-topic.
- 57% reported confusion in the the EM spectrum band-order memorisation block on at least one class test.
- 4 out of 5 students said the Displacement current concept was the most-practised derivation the night before boards.
- Average student took 5.0 hours for first-read and 2.4 hours for focused revision.
- Out of 10,380 students, 61% read these ch 8 physics class 12 notes at least twice before their boards.
Source: 2025-26 Class 12 Physics student poll. Sample of 10,380 students from CBSE schools across 16 states.
Other Resources for Class 12 Physics Chapter 8 Electromagnetic Waves
| Resource | Link |
|---|---|
| NCERT Solutions | Class 12 Electromagnetic Waves NCERT Solutions |
| Formula Sheet | Class 12 Electromagnetic Waves Formula Sheet |
| NCERT Book PDF | Class 12 Electromagnetic Waves NCERT Book PDF |
| Exemplar Book PDF | Class 12 Electromagnetic Waves NCERT Exemplar Book PDF |
| Exemplar Solutions | Class 12 Electromagnetic Waves NCERT Exemplar Solutions |
| Handwritten Notes | Electromagnetic Waves Handwritten Notes |
NCERT Handwritten Notes for Class 12 Physics - All Chapters
| Chapter | Resource |
|---|---|
| Chapter 1 | Electric Charges and Fields Handwritten Notes |
| Chapter 2 | Electrostatic Potential and Capacitance Handwritten Notes |
| Chapter 3 | Current Electricity Handwritten Notes |
| Chapter 4 | Moving Charges and Magnetism Handwritten Notes |
| Chapter 5 | Magnetism and Matter Handwritten Notes |
| Chapter 6 | Electromagnetic Induction Handwritten Notes |
| Chapter 7 | Alternating Current Handwritten Notes |
| Chapter 8 | Electromagnetic Waves Handwritten Notes |
| Chapter 9 | Ray Optics and Optical Instruments Handwritten Notes |
| Chapter 10 | Wave Optics Handwritten Notes |
| Chapter 11 | Dual Nature of Radiation and Matter Handwritten Notes |
| Chapter 12 | Atoms Handwritten Notes |
| Chapter 13 | Nuclei Handwritten Notes |
| Chapter 14 | Semiconductor Electronics Handwritten Notes |
Class 12 Physics Chapter 8 Electromagnetic Waves Handwritten Notes FAQs
Ques. What are the main topics in ch 8 physics class 12 notes?
Ans. The class 12 ch 8 physics notes cover displacement current, maxwell's equations, em wave properties, and electromagnetic spectrum.
Ques. What are the most-asked derivations in this chapter?
Ans. 3 derivations carry the chapter's mark weight: Displacement current concept, Speed of light c = 1/sqrt(mu_0 epsilon_0), EM wave transverse character, and others listed in the Derivations Index above.
Ques. How many formulas are in the ch 8 physics class 12 notes?
Ans. 6 formulas cover every numerical the chapter generates. The Quick-Reference Table above lists them with units. The physics class 12 chapter 8 pdf carries the same list on a single A4 cover sheet.
Ques. What is the weightage of ch 8 physics class 12?
Ans. Chapter 8 carries 2 marks in CBSE Class 12 Physics, 1 to 2 percent in JEE Main, and 0 to 1 question per year in NEET.
Ques. Where can I download the physics chapter 8 class 12 notes pdf?
Ans. The physics class 12 chapter 8 notes pdf is available directly on this page via the download card above. Both Normal and HD versions cover all 6 formulas, 3 derivations, and worked numericals.
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