Magnetism Class 6 ICSE — Physics Chapter 7

Magnetism class 6 ICSE is the subject of this chapter from the Class 6 Physics book. It explains what magnets are, how poles behave, and why like poles repel while unlike poles attract. The chapter also covers the types of magnets, the methods of making them, and how to store them safely. Each section below follows the book’s own order.

Download Magnetism Class 6 ICSE Physics Chapter 7 PDF

Download the Magnetism Class 6 ICSE Physics chapter PDF to revise offline or print for practice. It is the full chapter as printed in the book — 11 pages, 9 sections, 29 questions.

What is inside Chapter 7

11 pages · 9 sections · 29 exercise questions

• Intext Questions: 4 questions
• Intext Questions: 4 questions
• TEST YOURSELF: 0 questions
• A. Short Answer Questions :: 4 questions
• B. Long Answer Questions :: 17 questions

1 Like poles repel, unlike poles attract

Every magnet has two poles, a north pole and a south pole. This section shows how the poles behave when two magnets come close. The chapter uses a freely suspended bar magnet for the test. One magnet is held in the hand, while the other hangs from a thread.

When the north pole of the hand-held magnet is brought near the north pole of the suspended magnet, the suspended pole moves away. The same thing happens when two south poles face each other. This movement away is called repulsion.

Now bring the south pole of the hand-held magnet near the north pole of the suspended magnet. The suspended magnet swings towards the first one. This movement towards each other is called attraction.

The experiment proves the rule: like poles repel and unlike poles attract. This rule is the foundation for the rest of the chapter. Every later idea, from the true test of a magnet to how magnets are stored, builds on it.

2 Repulsion is the only true test for a magnet

The chapter defines like poles as two north poles or two south poles. Unlike poles are a north pole and a south pole facing each other.

Attraction alone does not prove an object is a magnet. A magnet attracts magnetic substances such as iron nails. It also attracts the unlike pole of another magnet. So when an object is pulled towards a magnet, the cause could be either one.

Repulsion is different. Repulsion happens only between like poles, and like poles only exist in magnets. When an object is repelled by a magnet, the object must be a magnet itself. This is why the chapter calls repulsion the only true test.

Common mistake: students often decide an object is a magnet because a magnet attracts it. That test fails. A paper clip is not a magnet, yet a magnet pulls it easily. Only repulsion gives a definite answer, a point that matters throughout this ICSE Class 6 chapter.

3 Magnetic poles always occur in pairs

What happens when you cut a bar magnet in half? The chapter says each piece becomes a complete new magnet. Every piece has its own north pole and its own south pole. Cutting again gives the same result. No matter how small the pieces, each one is a full magnet.

A single magnetic pole can never be isolated. You cannot obtain a north pole without a south pole. The two always travel together.

Worked pattern: suppose you break a bar magnet into seven equal pieces. Each piece is a complete magnet with one north pole and one south pole. That gives seven north poles in total and seven south poles in total. The answer the exam expects is seven north poles.

The idea applies to any number. A magnet broken into n pieces produces n north poles and n south poles.

4 TYPES OF MAGNETS

This is the core section of the chapter. It classifies magnets, names the parts of a bar magnet, and explains how magnets are made. The chapter groups magnets into natural, artificial, temporary, permanent and electromagnetic types. For the wider set of topics in this subject, you can explore the full Class 6 Physics book.

Artificial and natural magnets

Lodestone is an iron ore that shows magnetic properties naturally. It is the natural magnet. Artificial magnets are made from such natural sources. A piece of iron rubbed with lodestone picks up the same properties.

A Danish physicist, Hans Christian Oersted, discovered the electromagnet in 1819. He found that a magnetic field surrounds every wire carrying an electric current. That discovery opened the way for electromagnets used in bells, motors and many devices.

Temporary and permanent magnets

Temporary magnets are made of soft (pure) iron. They act as magnets only for a short time. As soon as the magnetising force is removed, they lose their magnetism. Paper clips and iron nails are examples.

Permanent magnets are made of steel, cobalt and nickel. They keep their magnetism for a long time even after the magnetising force is removed. The Class 6 ICSE syllabus expects you to tell the two apart clearly.

Various parts of a bar magnet

Know the names of the parts. Magnetic poles are the end points where most magnetic power is concentrated. The magnetic north pole is the end that points towards the geographic north when the magnet is freely suspended. The magnetic south pole points towards the geographic south.

The magnetic axis is the imaginary line joining the north and south poles. The length of a magnet is the total distance from the north pole to the centre and the centre to the south pole. The effective length is the distance between the two poles along the axis. The magnetic equator is an imaginary line that bisects the effective length.

Making magnets

The chapter gives four methods to make a magnet from a magnetic substance.

• Magnetic induction method: a nail near a magnet becomes magnetic while the magnet is present. Remove the magnet and the nail loses its power. The pins fall away. This temporary gain is magnetic induction.
• Single touch method: rub one pole of a magnet on an iron bar, always in one direction, several times. The bar becomes a magnet.
• Double touch method: place the north pole of one magnet and the south pole of another at the middle of the iron bar. Rub both outwards to the ends, starting from the middle each time.
• Electrical method: place a soft iron bar inside a coil of insulated wire and pass current. The bar becomes strongly magnetised. One end is north, the other south. Turn off the current and the bar loses nearly all its magnetism.

Electromagnets

An electromagnet is a current-carrying coil wrapped around a soft iron core. Its magnetism can be switched on or off. This makes it a temporary magnet.

The chapter gives three advantages over permanent magnets. First, an electromagnet can be magnetised and demagnetised by turning the current on or off. Second, it can be made stronger than any permanent magnet as needed. Third, its poles can be interchanged by reversing the current direction, which is impossible with a permanent magnet.

Strength depends on two factors: the amount of current flowing through the coil and the number of turns in the coil. More current gives a stronger magnet. More turns also give a stronger magnet.

Uses include the electric bell, telegraph sounder, telephone receiver, motor and loudspeaker. Electrical measuring instruments such as the galvanometer, ammeter and voltmeter use them. Huge electromagnets load and unload heavy iron objects at shipyards. Eye specialists use small ones to remove bits of iron lodged in the eye.

5 Demagnetising a Magnet

A magnet loses its magnetic properties in several ways. The chapter lists six causes.

• Repeated hammering destroys the magnetic properties.
• Rough handling does the same.
• Heating the magnet to a very high temperature while keeping it in the east-west direction also works.
• Passing alternating current through a coil around the magnet demagnetises it.
• Dropping it repeatedly on a hard surface is another cause.
• Self-demagnetisation happens slowly when the two poles are left free.

The chapter notes this last process is called self-demagnetisation. A magnet left alone loses its magnetism slowly over time.

Practical point: keep magnets away from heat and rough treatment. Store them properly so they keep their strength. The next section explains how.

6 Properties of a Bar Magnet

The chapter gives four properties of a bar magnet.

• Attractive property: a magnet attracts small pieces of iron filings.
• Directive property: a magnet suspended horizontally by a thin thread rests pointing in the north-south direction of the earth.
• Like poles repel each other and unlike poles attract each other.
• Poles always exist in pairs, and a single pole can never exist.

To recall these four, build a mnemonic from the first letters A, D, L, P. One phrase to remember them: ‘A Dog Loves Poles.’ A stands for attractive, D for directive, L for like poles repel, P for poles exist in pairs. Say the phrase and the four properties come back in order.

7 Storing of Magnets

When magnets are not in use, they should be stored in magnetic keepers. A magnetic keeper is a cardboard box with one or two soft iron pieces.

Two bar magnets are placed with their opposite poles close to each other. A soft iron keeper is attached to them. A piece of wood separates the two magnets. This arrangement stops the magnets from losing their magnetism.

A U-shaped magnet needs only one magnetic keeper, because its poles are already close together.

Why does this work? The soft iron keeper completes a magnetic circuit between the poles. This keeps the magnetic field inside the keeper instead of letting it spread out. The magnet keeps its strength for longer, a rule worth remembering from this Magnetism class 6 ICSE chapter.

8 KNOWLEDGE BANK

The chapter ends its main content with three short facts.

• Ceramic magnets are made from the oxides of iron, nickel and beryllium.
• The magnetic compass is a device used by travellers, sailors and navigators to find direction.
• The earth behaves as a huge magnet, although there is no actual magnet inside it.

These facts appear often in short-answer questions. Remember the three materials for ceramic magnets and the compass users. The earth-as-magnet idea connects to the directive property of a bar magnet from section 6.

9 Uses of Magnets

The chapter lists common uses of magnets. Read through the list once and note the pattern.

• Magnets appear in the magnetic compass, door bells, refrigerators and cupboard doors.
• They are used in dynamos, motors, loudspeakers, microphones, floppy disks, stereo speakers and televisions.
• Ceramic magnets are used in computers.
• Magnetic tapes are used in tape recorders and radio recorders.
• Magnets are used in toys to give a magic effect.

Notice how many devices contain a magnet without showing it. A refrigerator door holds shut because of a magnet. A computer stores data with the help of ceramic magnets. The list connects this Magnetism class 6 ICSE chapter to daily life. To see what else Class 6 offers across subjects, browse the Class 6 books list.

What to practise from Magnetism Class 6 ICSE

This chapter carries its practice in several blocks. Work through them in the order they appear.

• Intext Questions (4 questions): the first set asks about shapes of magnets, the iron ore that shows magnetic properties, examples of temporary magnets, and the discoverer of the electromagnet.
• Intext Questions (4 questions): the second set asks for the methods of making magnets, two uses of an electromagnet, the meaning of demagnetisation, and the use of magnetic keepers.
• TEST YOURSELF, A. Short Answer Questions (4 questions): true or false statements, fill in the blanks, matching, and tick-the-correct-answer.
• TEST YOURSELF, B. Long Answer Questions (17 questions): definitions, experiments and application questions.

Most Magnetism class 6 ICSE exam questions map to the sections above. Pole-pair questions test section 3. The true test of magnetism tests section 2. Magnetising methods test section 4. Storing magnets tests section 7. For the official syllabus details, check the official CISCE website.

Magnetism Class 6 ICSE frequently asked questions

What does magnetism class 6 icse cover in this chapter?

This chapter explains the basics of magnetism. It covers pole behaviour, the true test of a magnet, the types of magnets, and the parts of a bar magnet. It also shows how magnets are made, demagnetised, stored and used.

Why is repulsion the only true test for a magnet?

Attraction does not prove an object is a magnet because a magnet attracts magnetic substances too. Repulsion happens only between like poles, and like poles only exist in magnets. So an object repelled by a magnet is definitely a magnet.

What is the difference between a temporary and a permanent magnet?

A temporary magnet is made of soft iron and loses its magnetism as soon as the magnetising force is removed. A permanent magnet is made of steel, cobalt or nickel and keeps its magnetism for a long time.

What happens if you cut a bar magnet into pieces?

Every piece becomes a complete new magnet with its own north and south poles. A single pole can never be isolated. For example, breaking a magnet into seven pieces gives seven north poles.

How should magnets be stored so they keep their magnetism?

Store bar magnets in magnetic keepers with opposite poles close to each other and a soft iron keeper attached. A piece of wood separates the two magnets. A U-shaped magnet needs only one keeper.

Reference: ICSE Class 6 Physics textbook material, chapter 7: Magnetism — CISCE-aligned.