NCERT Class 12 Physics Physics Part-I: Chapter 5 — 1 INTRODUCTION
This chapter, Magnetism and Matter, introduces students to the fundamental concepts of magnetism. It explains that magnetic phenomena are universal, affecting everything from galaxies to atoms. The chapter traces the origin of the word 'magnet' and revisits the discovery that moving charges produce magnetic fields. It details common ideas about magnetism, such as the Earth behaving like a magnet, the behavior of a freely suspended bar magnet, magnetic poles, and the impossibility of magnetic monopoles. The text also introduces the concept of magnetic field lines, comparing them to electric field lines and highlighting their continuous closed-loop nature. The chapter sets the stage for exploring magnetic materials and their properties, crucial for Class 12 Physics and CBSE curriculum.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 12 |
| Subject | Physics |
| Book | Physics Part-I |
| Chapter | Chapter 5 — 1 INTRODUCTION |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 4 minutes |
| Word count | 692 |
Learning outcomes
- Understand the universality and historical context of magnetism.
- Identify the properties of bar magnets and magnetic poles.
- Explain the concept of magnetic field lines and their properties.
- Recognize the absence of magnetic monopoles.
- Differentiate between magnetic and electric dipoles.
Vocabulary
| Word | Meaning |
|---|---|
| Magnetism | A physical phenomenon produced by moving electric charges and magnetic dipoles, attracting or repelling other magnets. |
| Magnetic field | The region around a magnetic material or a moving electric charge within which the force of magnetism acts. |
| Bar magnet | A rectangular magnet, typically with a north and south pole. |
| North pole | The pole of a magnet that points towards the Earth's geographic north. |
| South pole | The pole of a magnet that points towards the Earth's geographic south. |
| Magnetic monopole | An isolated magnetic north or south pole, which does not exist in nature. |
| Magnetic field lines | Imaginary lines used to represent the direction and strength of a magnetic field. |
| Magnetic dipole | A system with a magnetic north and south pole, like a bar magnet. |
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Practice questions
- From where is the word 'magnet' derived? Answer: The word 'magnet' is derived from the name of an island in Greece called Magnesia.
- What is the main difference between electric charges and magnetic poles regarding isolation? Answer: Electric charges can be isolated (positive or negative charges), but magnetic poles cannot be isolated; they always exist in pairs (north and south).
- What happens if a bar magnet is broken into two halves? Answer: If a bar magnet is broken into two halves, two similar bar magnets with somewhat weaker properties are formed, each with a north and south pole.
- How do magnetic field lines differ from electric field lines of an electric dipole? Answer: Magnetic field lines form continuous closed loops, whereas electric field lines begin from a positive charge and end on a negative charge or escape to infinity.
Practice MCQs
Q1. Who is credited with the discovery that moving charges produce magnetic fields?
Explanation: The discovery that moving charges or electric currents produce magnetic fields is credited to scientists like Oersted, Ampere, Biot, and Savart in the early nineteenth century.
Q2. When a bar magnet is freely suspended, which direction does it point?
Explanation: When a bar magnet is freely suspended, it aligns itself with the Earth's magnetic field, pointing approximately in the north-south direction.
Q3. What is the term for an isolated magnetic north or south pole?
Explanation: Isolated magnetic north or south poles are known as magnetic monopoles, which are stated to not exist in nature.
Q4. The pattern of iron filings around a bar magnet suggests it behaves like a:
Explanation: The arrangement of iron filings around a bar magnet, forming a pattern, suggests that the magnet has two poles, similar to an electric dipole.
Q5. Unlike electric field lines, magnetic field lines form:
Explanation: Magnetic field lines of a magnet or a solenoid form continuous closed loops, indicating that magnetic poles always exist in pairs.
Frequently asked questions
What is magnetism?
Magnetism is a physical phenomenon associated with magnetic fields, produced by moving electric charges or magnetic dipoles, which exert attractive or repulsive forces on other magnets.
Why is it impossible to isolate a magnetic pole?
Magnetic poles always exist in pairs. If a magnet is broken, each piece becomes a new magnet with both a north and a south pole. Isolated magnetic poles, or magnetic monopoles, have not been observed.
What are magnetic field lines?
Magnetic field lines are imaginary lines used to visualize the direction and strength of a magnetic field. They form continuous closed loops.
How does the Earth behave magnetically?
The Earth behaves like a giant magnet, with its magnetic field pointing approximately from the geographic south to the geographic north.
What is the significance of the pattern of iron filings around a bar magnet?
The pattern of iron filings around a bar magnet helps to visualize the magnetic field lines and suggests that the magnet acts as a magnetic dipole with distinct poles.
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NCERT Class 12 Physics — Physics Part-I — Chapter 5 — 1 INTRODUCTION. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.