Magnets
📚 Topic Overview: Magnetism Basics & Types
This chapter introduces the foundational concepts of magnets — their discovery,
nature, types, and important properties. These concepts appear consistently in
competitive exams across India. Understanding them helps learners answer
application-based, reasoning-based, and concept-based questions effectively.
1. Discovery of Magnets
Concept / Theory
Magnets were discovered thousands of years ago when people found a black rock
called lodestone. It attracted small pieces of iron.
This was the earliest evidence of magnetism. The name “magnet” comes from
Magnesia, a region in ancient Greece where these stones were found.
Analogy / Examples
- A lodestone behaves like a natural magnet toy that can pull iron pins
without touching them.
Conversions/Formulas
- No formula is used here — this is a historical/observational concept.
| English | Telugu |
|---|---|
| Lodestone | చుంబక శిల |
| Magnetism | చుంబకత్వం |
| Attraction | ఆకర్షణ |
In olden days, travellers used pieces of lodestone to identify directions
because the stone always settled in a north–south direction when suspended.
Remember: Magnesia → Magnet. A direct link often asked in exams.
2. Magnetic & Non-Magnetic Substances
Concept / Theory
All materials do not respond to magnets. Materials that are attracted by magnets
are called magnetic substances.
Materials not attracted by magnets are called
non-magnetic substances.
Classification Table
| Magnetic | Non-Magnetic |
|---|---|
| Iron | Wood |
| Nickel | Plastic |
| Cobalt | Glass |
Example / Analogy
- When a magnet is brought near a bunch of keys, only the iron keys move
towards the magnet.
| English | Telugu |
|---|---|
| Magnetic | ఆకర్షిత పదార్థం |
| Non-Magnetic | ఆకర్షణ లేని పదార్థం |
| Separation | విడిపించడం |
In rice mills, magnets are fixed on conveyor belts to remove iron particles
from bulk grain loads. Only magnetic materials are picked up.
Only three common metals are strongly magnetic: Iron, Cobalt, Nickel.
3. Types of Magnets
Concept / Theory
Magnets can be natural or artificial. Natural magnets occur in nature but are
usually weak. Artificial magnets are made in different shapes like bar,
horseshoe, ring, or disc magnets. They are stronger and used in instruments,
machines, toys, speakers, and sensors.
Comparison Table
| Type | Details |
|---|---|
| Natural Magnet | Weak; found as lodestone |
| Bar Magnet | Rectangular; widely used in labs |
| Horseshoe Magnet | U-shaped; strong at both ends |
| Ring Magnet | Used in speakers, motors |
| Disc Magnet | Flat circular magnet used in toys and sensors |
| English | Telugu |
|---|---|
| Bar Magnet | దండు చుంబకం |
| Horseshoe Magnet | గుర్రపు నాలు ఆకార చుంబకం |
| Ring Magnet | ఉంగరం చుంబకం |
Horseshoe magnets are used in scrapyards to lift heavy iron blocks because
their poles are concentrated close together, increasing their strength.
Remember: Natural = Weak, Artificial = Strong.
4. Properties of Magnets (with Exam Tips & Memory Sheet)
Concept / Theory
All magnets show certain fixed properties:
- Magnets attract iron, cobalt, and nickel.
- Every magnet has two poles: North and South.
- Like poles repel; unlike poles attract.
- The strength of a magnet is highest at its poles.
- A freely suspended magnet aligns in the North–South direction.
- Heating, hammering, and dropping can reduce magnetism.
Behaviour Table
| Pole Combination | Result |
|---|---|
| North – North | Repel |
| South – South | Repel |
| North – South | Attract |
| English | Telugu |
|---|---|
| Poles | ధ్రువాలు |
| Repulsion | వికర్షణ |
| Attraction | ఆకర్షణ |
A compass works because its needle is a tiny magnet that aligns with Earth’s
magnetic field. This allows travellers and fishermen to navigate correctly.
Memory Formula Sheet
- Poles always come in pairs.
- Like poles = Repel; Unlike poles = Attract.
- Strongest region = Poles.
- Magnet + Heat/Hammer/Drop → Weak magnet.
- Earth acts like a huge bar magnet.
A common trap in competitive exams: “Which metals are magnetic?”
The correct group is ONLY: Iron, Cobalt, Nickel.