Chapters

Scroll →

Magnet: Why Certain Objects Attract and Point North

Magnets are familiar objects.
We see them in compasses, speakers, electric motors, fridge doors, and toys.
But magnetism is not just about attraction.
It explains direction, navigation, and invisible forces acting at a distance.

This chapter explains:

  • What magnets are
  • Types of magnets
  • Properties of magnets
  • Why Earth itself behaves like a giant magnet

Natural and Artificial Magnets

A magnet is a substance that attracts magnetic materials such as iron, cobalt, and nickel. Magnets are broadly classified into:

  • Natural magnets
  • Artificial magnets

Natural Magnets

Natural magnets are found in nature. The most common natural magnet is lodestone.

Properties:

  • Lodestone contains magnetite
  • It attracts iron naturally
  • It was used in early navigation

Natural magnets are weak and irregular in shape.

Artificial Magnets

Artificial magnets are man-made magnets. They are stronger and made for specific purposes.

Common shapes:

  • Bar magnet
  • Horseshoe magnet
  • Cylindrical magnet

Artificial magnets are widely used because their strength and shape can be controlled.

Types of Artificial Magnets (Based on Permanence)

  • Permanent magnets: retain magnetism for a long time
Example: bar magnet
  • Temporary magnets: lose magnetism easily
Example: soft iron core
  • Electromagnets: magnetism produced by electric current
Example: electric cranes

Magnetic Materials and Non-Magnetic Materials

  • Magnetic materials: iron, cobalt, nickel
  • Non-magnetic materials: wood, plastic, glass
    This classification is often tested in MCQs.

Properties of a Magnet

Magnets show some unique properties that help us identify them.

Attractive Property

A magnet attracts magnetic substances like iron filings. Attraction is strongest at the ends of the magnet, called magnetic poles.

Poles of a Magnet

Every magnet has two poles:

  • North pole
  • South pole

Poles always occur in pairs.

Like Poles Repel, Unlike Poles Attract

  • North–North → repulsion
  • South–South → repulsion
  • North–South → attraction

This property is fundamental to magnetism.

Directive Property

A freely suspended magnet always aligns itself in the north–south direction. This property is used in compasses for navigation.

Strength of Magnet is Maximum at Poles

The magnetic force is strongest at the poles and weakest at the centre. This can be seen by sprinkling iron filings on a magnet.

No Isolated Magnetic Poles

Magnetic poles cannot exist alone. If a magnet is cut into two pieces:

  • Each piece becomes a magnet
  • Each piece has both north and south poles

This is an important exam trap.

Methods of Magnetisation

Magnets can be made using different methods.

Stroking Method

Iron is stroked repeatedly with a magnet in one direction.

Electrical Method

Passing electric current through a coil around iron produces magnetism.

Demagnetisation

A magnet can lose its magnetism due to:

  • Heating
  • Hammering
  • Dropping repeatedly
    Proper storage prevents demagnetisation.

Storage of Magnets

  • Bar magnets are stored in pairs with unlike poles together
  • Soft iron keepers are used at ends
  • Horseshoe magnets are stored with keepers

This is a very common theory question.

Earth as a Magnet

Earth behaves like a giant magnet.
It has:

  • Magnetic north pole
  • Magnetic south pole

This explains why a compass needle points north–south.

Magnetic Poles of Earth

The magnetic south pole of Earth lies near the geographical north pole.

That is why:

  • North pole of a magnet points towards Earth’s north

This is a frequent source of confusion in exams.

Magnetic Axis and Geographic Axis

  • Geographic axis: passes through geographic poles
  • Magnetic axis: passes through magnetic poles

These two axes are not exactly the same.

Magnetic Declination

Magnetic declination is the angle between:

  • Geographic north
  • Magnetic north

It varies from place to place.

Importance of Earth’s Magnetism

  • Navigation using compass
  • Protection from harmful solar radiation
  • Direction finding in animals and birds

MAGNET – FAQs

What is a magnet?


A magnet is a substance that attracts magnetic materials like iron.

What is lodestone?


A natural magnet found in nature.

Can a magnet have only one pole?


No, magnetic poles always exist in pairs.

Where is magnetism strongest?


At the poles of a magnet.

Why does a magnet point north–south when suspended?


Due to Earth’s magnetic field.

What happens if a magnet is cut into two pieces?


Each piece becomes a complete magnet.

Are all metals magnetic?


No, only iron, cobalt, and nickel are magnetic.

Why are soft iron keepers used while storing magnets?


To prevent loss of magnetism.

Is Earth a magnet?

Yes, Earth behaves like a giant magnet.

Is magnetic north same as geographic north?


No, they are different.

Last-Moment Notes (Cheat Sheet)

MAGNET

  • Magnet attracts iron, cobalt, nickel
  • Natural magnet → lodestone
  • Artificial magnets are stronger and shaped
  • Every magnet has north and south poles
  • Like poles repel, unlike poles attract
  • Magnetic force is maximum at poles
  • Isolated magnetic poles do not exist
  • Freely suspended magnet points north–south
  • Magnet loses strength by heating, hammering, dropping
  • Bar magnets stored with unlike poles together
  • Soft iron keepers prevent demagnetisation
  • Earth behaves like a giant magnet
  • Magnetic north ≠ geographic north