NCERT Class 12 Physics Physics Part-I: Chapter 6 — 1 INTRODUCTION
This chapter introduces the concept of Electromagnetic Induction, a phenomenon where electric current is generated by varying magnetic fields. It begins by highlighting the historical view of electricity and magnetism as separate entities and then details the groundbreaking experiments by Michael Faraday and Joseph Henry in the 1830s. These experiments demonstrated that changing magnetic fields could induce electric currents in closed coils. The chapter explains that this induction is due to the relative motion between a magnet and a coil, or between two coils. It emphasizes the practical utility of this discovery, which forms the basis for modern generators and transformers, significantly contributing to the progress of civilization. The initial experiments with a bar magnet and a coil connected to a galvanometer are described to illustrate the principles of induced current and its dependence on motion and magnetic field changes.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 12 |
| Subject | Physics |
| Book | Physics Part-I |
| Chapter | Chapter 6 — 1 INTRODUCTION |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 4 minutes |
| Word count | 669 |
Learning outcomes
- Understand the historical context of electricity and magnetism.
- Explain the phenomenon of electromagnetic induction.
- Describe Faraday's and Henry's experiments on electromagnetic induction.
- Recognize the importance of relative motion between magnets and coils.
- Appreciate the practical applications of electromagnetic induction in modern technology.
Vocabulary
| Word | Meaning |
|---|---|
| Electromagnetic Induction | The phenomenon in which electric current is generated in a conductor when it is exposed to a changing magnetic field. |
| Magnetic Field | A region around a magnetic material or a moving electric charge within which the force of magnetism acts. |
| Electric Current | A flow of electric charge. |
| Galvanometer | An instrument used for detecting and measuring electric current. |
| Induced Current | An electric current produced in a conductor by a changing magnetic field. |
| Relative Motion | Motion of one object with respect to another. |
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Practice questions
- Who demonstrated conclusively that electric currents were induced in closed coils when subjected to changing magnetic fields? Answer: Michael Faraday and Joseph Henry.
- What happens to the galvanometer pointer when a bar magnet is held stationary near a coil? Answer: The galvanometer shows no deflection.
- What is the phenomenon called in which electric current is generated by varying magnetic fields? Answer: Electromagnetic induction.
- What is the significance of the relative motion between a magnet and a coil in electromagnetic induction? Answer: It is responsible for the generation (induction) of electric current in the coil.
Practice MCQs
Q1. Who are credited with demonstrating that changing magnetic fields can induce electric currents?
Explanation: Michael Faraday and Joseph Henry conducted experiments around 1830 that conclusively showed electric currents could be induced by changing magnetic fields.
Q2. According to the text, what naturally raises the question of whether moving magnets can produce electric currents?
Explanation: The text states that since moving electric charges produce magnetic fields, it naturally leads to the question of whether the converse effect (moving magnets producing currents) is possible.
Q3. What instrument is used to detect the presence of electric current in the experiments described?
Explanation: The text explicitly mentions that a galvanometer's pointer deflects, indicating the presence of electric current in the coil.
Q4. When a bar magnet is pulled away from a coil, what is observed about the galvanometer's deflection?
Explanation: The text states that when the magnet is pulled away from the coil, the galvanometer shows deflection in the opposite direction, indicating a reversal of current.
Q5. What is the primary cause for the generation of electric current in the coil during the experiments?
Explanation: The chapter emphasizes that it is the relative motion between the magnet and the coil that is responsible for the induction of electric current.
Frequently asked questions
What was the initial view of electricity and magnetism?
For a long time, electricity and magnetism were considered separate and unrelated phenomena.
What discovery established the link between electricity and magnetism?
Experiments by Oersted, Ampere, Faraday, and Henry established that moving electric charges produce magnetic fields, and changing magnetic fields can induce electric currents.
Who are the key scientists associated with the discovery of electromagnetic induction?
Michael Faraday in England and Joseph Henry in the USA are credited with demonstrating electromagnetic induction.
What is electromagnetic induction?
Electromagnetic induction is the phenomenon in which electric current is generated in a conductor when it is subjected to a changing magnetic field.
What causes the electric current to be induced in the coil in Faraday's experiment?
The relative motion between the bar magnet and the coil causes the magnetic field through the coil to change, inducing an electric current.
Does the galvanometer deflect when the magnet is stationary near the coil?
No, the galvanometer does not show any deflection when the magnet is held stationary relative to the coil.
What is the practical importance of electromagnetic induction?
The phenomenon of electromagnetic induction is crucial for the development of modern generators and transformers, forming the basis of much of today's electrical technology.
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NCERT Class 12 Physics — Physics Part-I — Chapter 6 — 1 INTRODUCTION. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.