Class 12 Physics Chapter 4 Moving Charges and Magnetism covers every formula from Lorentz force to the cyclotron equation. The chapter carries 6 marks in CBSE and appears in JEE Main and NEET every year. Download the Formula Sheet PDF on this page for a complete single-page revision reference.
- CBSE Boards: Chapter 4 carries 6 marks - expect one 3-mark and one 5-mark question.
- JEE Main: 4 to 5 percent of questions come from this chapter, mostly cyclotron and Biot-Savart numericals.
- NEET: 1 to 2 questions per year from Lorentz force, cyclotron, and galvanometer topics.
Moving Charges and Magnetism Class 12 Physics Formulas: Complete Reference
The 10 formulas below cover every numerical in Class 12 Physics Chapter 4. Each row gives the concept, the formula, and the SI unit. The PDF above lists all of them on a single A4 page, calibrated for both CBSE Boards and JEE Main.
| Concept | Formula | SI Unit |
|---|---|---|
| Lorentz force | F = q (E + v cross B) | newton |
| Force on current-carrying wire | F = I L cross B | newton |
| Biot-Savart law | dB = (mu_0 / 4 pi) I dL cross r_hat / r squared | tesla |
| Field of infinite straight wire | B = mu_0 I / (2 pi d) | tesla |
| Field at centre of circular loop | B = mu_0 I / (2 R) | tesla |
| Field on axis of circular loop | B = mu_0 I R squared / (2 (R squared + x squared) to the 3/2) | tesla |
| Ampere's law | closed integral B . dL = mu_0 I_enc | n/a |
| Solenoid (long) | B = mu_0 n I | tesla |
| Cyclotron radius | r = m v / (q B) | metre |
| Cyclotron frequency | f = q B / (2 pi m) | hertz |
Moving Charges and Magnetism Class 12: Video Lecture
Source: JEE Wallah on YouTube
Lorentz force - combined electric and magnetic action.
Topic-by-Topic Breakdown: Moving Charges and Magnetism Chapter 4
Chapter 4 divides into 6 sub-topic blocks. Each block has its own formulas and typical mark allocation in CBSE:
- Magnetic field and Lorentz force: 2-mark questions on F = q(v cross B) and F = IL cross B
- Biot-Savart law: 3-mark derivation of field due to a current element
- Field of a straight wire and circular loop: 5-mark derivation questions
- Ampere's circuital law: 3-mark numericals on solenoid and toroid
- Force between parallel currents: 2-mark on F/L = mu_0 I_1 I_2 / (2 pi d)
- Cyclotron and galvanometer: 3-mark on r = mv/qB and ammeter/voltmeter conversion
Class 12 Physics Chapter 4 Weightage in CBSE, JEE and NEET
The table below maps how Chapter 4 compares to every other Class 12 Physics chapter. Marks are CBSE board averages over the last five papers.
| 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 |
Moving Charges and Magnetism Previous Year Questions (2021-2026)
The table below maps every CBSE Board, JEE Main, and NEET appearance of Chapter 4 topics over the last six sessions.
| Year | CBSE Board | JEE Main | NEET |
|---|---|---|---|
| 2026 | Field on axis of circular loop (5 marks) | Cyclotron radius numerical (4 marks) | Force on a moving charge and field of a current (2 questions) |
| 2025 | Force between parallel currents (3 marks) | Solenoid field with Ampere's law | Lorentz force MCQ |
| 2024 | Biot-Savart applied to straight wire (5 marks) | Charged particle in B field | Moving-coil galvanometer |
| 2023 | Magnetic field of toroid (3 marks) | Force on current-carrying loop | Cyclotron frequency MCQ |
| 2022 | Velocity selector derivation (3 marks) | Field at centre of loop | Right-hand rule MCQ |
| 2021 | - | Hall effect basics | Ampere's law statement |
FBV right-hand rule - Lorentz force direction.
Common Mistakes in Moving Charges and Magnetism
Mistake 1: Substituting values before simplifying the formula. Always rearrange to isolate the unknown first.
Mistake 2: Forgetting unit conversion. Use SI units everywhere unless the question specifies otherwise.
Mistake 3: Using approximate constants (k = 9 x 10 to 9 vs 8.99 x 10 to 9). For 5-mark numericals, use the value given in the question.
Mistake 4: Confusing similar-looking formulas, for example axial vs equatorial dipole, or solenoid vs toroid. The formula table above separates them clearly.
Each one costs 1 to 2 marks.
Student Feedback
In a Collegedunia poll of 12,640 Class 12 Physics students before the 2026 boards, 74% of students rated the formula sheet as their most-used revision resource, ahead of full chapter notes and solved-example PDFs.
- 74% of students placed the formula sheet at the top of their revision priority list.
- 58% reviewed the formula sheet daily in the last 7 days before the boards.
- 4 out of 5 students keep a printed copy of the formula sheet in their notebook.
- Average revision time: 12 minutes per chapter for a focused pass.
Source: 2025-26 Class 12 Physics student poll. Sample of 12,640 students from CBSE schools across 16 states.
Other Resources for Class 12 Physics Moving Charges and Magnetism
| Resource | Link |
|---|---|
| NCERT Notes | Moving Charges and Magnetism Notes |
| NCERT Solutions | Moving Charges and Magnetism NCERT Solutions |
| NCERT Book PDF | Moving Charges and Magnetism NCERT Book PDF |
| Exemplar Book PDF | Moving Charges and Magnetism Exemplar Book PDF |
| Exemplar Solutions | Moving Charges and Magnetism Exemplar Solutions |
| Handwritten Notes | Moving Charges and Magnetism Handwritten Notes |
| Formula Sheet | Moving Charges and Magnetism Formula Sheet |
NCERT Formula Sheets for All Class 12 Physics Chapters
| Chapter | Resource |
|---|---|
| Chapter 1 | Electric Charges and Fields Formula Sheet |
| Chapter 2 | Electrostatic Potential and Capacitance Formula Sheet |
| Chapter 3 | Current Electricity Formula Sheet |
| Chapter 4 | Moving Charges and Magnetism Formula Sheet |
| Chapter 5 | Magnetism and Matter Formula Sheet |
| Chapter 6 | Electromagnetic Induction Formula Sheet |
| Chapter 7 | Alternating Current Formula Sheet |
| Chapter 8 | Electromagnetic Waves Formula Sheet |
| Chapter 9 | Ray Optics and Optical Instruments Formula Sheet |
| Chapter 10 | Wave Optics Formula Sheet |
| Chapter 11 | Dual Nature of Radiation and Matter Formula Sheet |
| Chapter 12 | Atoms Formula Sheet |
| Chapter 13 | Nuclei Formula Sheet |
| Chapter 14 | Semiconductor Electronics Formula Sheet |
Class 12 Physics Chapter 4 Moving Charges and Magnetism Formula Sheet FAQs
Ques. How many formulas are in the Class 12 Physics Chapter 4 formula sheet?
Ans. 10 formulas cover every numerical the chapter generates. The Quick-Reference Table above lists them with units. The PDF carries the same list on a single A4 page for night-before revision.
Ques. What is the weightage of Class 12 Physics Chapter 4?
Ans. Chapter 4 carries 6 marks in CBSE Class 12 Physics, 4 to 5 percent in JEE Main, and 1 to 2 questions per year in NEET. The formula sheet covers the formulas needed for every variant.
Ques. Where can I download the Moving Charges and Magnetism formula sheet PDF?
Ans. The formula sheet PDF is available directly on this page via the flipbook above. All 10 formulas plus JEE extensions are included in the PDF.
Ques. Are JEE Main extensions covered in this formula sheet?
Ans. Yes. The formula sheet includes 2 to 3 extensions that JEE Main and JEE Advanced test but CBSE Boards rarely ask. These are flagged with a distinct marker in the PDF.
Ques. What is the most-asked formula in Moving Charges and Magnetism?
Ans. Lorentz force is the foundational formula and appears in most Chapter 4 numericals. The full list of high-frequency formulas is in the Quick-Reference Table above.
Comments