Exploring Magnets

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Lodestones are naturally occurring magnets discovered in ancient times. The magnets used by sailors in the olden days were based on lodestones. Later, people found out that magnets could also be made from pieces of iron.

Artificial magnets are magnets made by humans from pieces of iron or other materials. Examples of their use: magnets in school laboratories, and those used in pencil boxes, stickers, and toys.

The chapter shows bar magnets, U-shaped magnets, and ring magnets.

The materials which are attracted towards a magnet are called magnetic materials. Iron is a magnetic material. Nickel and cobalt are other metals that are also magnetic. Some of their combinations with other metals are also attracted towards magnets.

The materials which are not attracted towards a magnet are called non-magnetic materials. Examples include wood, plastic, rubber, and glass.

Maximum iron filings stick near the ends (poles) of the bar magnet, while very few iron filings stick to the remaining part of the magnet. This shows that the magnetic attraction is strongest at the poles.

The two poles of a magnet are called the North pole and the South pole. The end of the magnet pointing towards the north direction is the North pole, and the other end pointing towards the south is the South pole.

No, it is not possible to obtain a magnet with a single pole. If a magnet is broken into smaller pieces, North and South poles always exist in pairs, even in the smallest piece of the magnet. A single North pole or a single South pole cannot exist.

A freely suspended magnet rests along the north-south direction because our Earth itself behaves like a giant magnet. The Earth's magnetic influence aligns the suspended magnet in the north-south direction.

A magnetic compass is a small device developed in olden days for finding directions. It has a magnet in the shape of a needle which can rotate freely. The needle of a magnetic compass indicates the north-south direction.

A magnetic compass is usually a small circular box with a transparent cover. The magnet, in the shape of a needle, is mounted on a pin standing on the bottom of the box, balanced so it can rotate freely. The end of the needle which rests in the North direction is usually painted red. Below the needle, there is a dial with directions marked on it.

Suspend the piece of metal freely with a thread. If it always comes to rest along the north-south direction, it is a magnet. An ordinary iron bar can rest along any direction; only magnets rest along the north-south direction when freely suspended.

Unlike poles of two magnets — that is, the North pole of one magnet and the South pole of another magnet — attract each other. They pull towards each other.

Like poles — either the North poles or the South poles of both magnets — repel each other. They push away from each other.

When an iron bar is brought near a magnet, both ends of the iron bar are attracted by both the North and South poles of the magnet. But when another magnet's like pole is brought near, repulsion occurs. Since only a magnet can be repelled, repulsion is the sure test of magnetism.

The compass needle moves away (deflects away). This is because like poles repel each other — the North pole of the bar magnet and the North pole of the compass needle are like poles.

The compass needle moves closer. This is because unlike poles attract each other — the South pole of the bar magnet and the North pole of the compass needle are unlike poles.

The matsya-yantra (or machchh-yantra) was a device used by Indians for navigation at sea, much before the widespread use of the modern magnetic compass. It consisted of a magnetised fish-shaped iron piece kept in a vessel of oil.

Magnets should be stored in pairs with unlike poles on the same side. A piece of wood should be kept in between, and two pieces of soft iron should be placed across the ends. This keeps them safe and maintains their magnetism.

We should not heat magnets, drop them, or hammer them. We should also not keep them near mobile phones or remote controls. Magnets should be treated with care.

Introduction: Reshma, a young story-writer from Kerala, discovered the magnetic compass while writing a story.
Key Points:
1. The story problem — Her story's sailors lost their way in a storm when stars were not visible.
2. Her research — She searched the internet and her school library for how sailors found directions.
3. The discovery — She learnt that travellers used a device called the magnetic compass for directions.
Conclusion: This search made Reshma curious to learn more about magnets and compasses.

Introduction: Magnets have an interesting history, from natural lodestones to modern artificial magnets.
Key Points:
1. Natural magnets — Naturally occurring magnets, called lodestones, were discovered in ancient times.
2. Early compasses — The magnets used by sailors in the olden days were based on these lodestones.
3. Artificial magnets — People later found magnets could be made from iron pieces; today magnets use different materials.
Conclusion: School laboratory magnets and toy magnets today are all artificial magnets of many shapes.

Introduction: A simple activity tests which objects stick to a magnet and which do not.
Key Points:
1. The activity — Bring a magnet near different objects one by one and observe which stick to it.
2. Observations — Some objects, like iron items, stick; others like plastic, wood and rubber do not.
3. Conclusion — Materials attracted towards a magnet are magnetic; others are non-magnetic materials.
Conclusion: Iron, nickel and cobalt are magnetic materials, while wood, plastic and rubber are non-magnetic.

Introduction: The iron filings activity shows that a magnet attracts most strongly at its ends.
Key Points:
1. The activity — Spread iron filings on paper, place a bar magnet over them and tap gently.
2. Observation — Maximum filings stick near the magnet's ends; very few stick elsewhere.
3. Conclusion — The two ends, where attraction is strongest, are called the North and South poles.
Conclusion: This demonstrates that a magnet's strength is concentrated at its two poles.

Introduction: Suspending a bar magnet freely reveals a very useful property of magnets.
Key Points:
1. The setup — Suspend a bar magnet with a thread tied to its middle, balanced horizontally.
2. The observation — Rotate it gently; it always comes to rest along the north-south direction.
3. The reason — This happens because our Earth itself behaves like a giant magnet.
Conclusion: The end pointing north is the North pole; this property helps us find directions.

Introduction: Repeating the suspension activity with an iron bar gives a different result.
Key Points:
1. The activity — Suspend a small iron bar freely with a thread, exactly like the bar magnet.
2. Observation — The iron bar does not rest along north-south; it can rest in any direction.
3. Conclusion — Only magnets rest along the north-south direction, not ordinary iron pieces.
Conclusion: This activity provides a way to test whether a piece of metal is a magnet.

Introduction: A magnetic compass can be made at home using simple everyday materials.
Key Points:
1. Magnetise the needle — Rub a sewing needle with a magnet's pole along its length, 30–40 times.
2. Test the needle — Bring iron filings near; if they get attracted, the needle has become a magnet.
3. Float it — Pass the needle through a cork and float it in a water bowl; it points north-south.
Conclusion: The floating magnetised needle always rests along the north-south direction like a compass.

Introduction: An activity with two bar magnets shows how the poles of magnets interact.
Key Points:
1. The setup — Place magnet A on round pencils; bring magnet B's end near magnet A's end.
2. Attraction observed — Unlike poles, North of one and South of another, attract each other.
3. Repulsion observed — Like poles, North-North or South-South, push each other away.
Conclusion: Unlike poles attract while like poles repel; repulsion identifies true magnets.

Introduction: An activity tests whether materials block the magnetic effect between magnet and compass.
Key Points:
1. The activity — Bring a magnet near a compass needle, then place a piece of wood between them.
2. Repeat with materials — Replace the wood with cardboard, a thin plastic sheet and a thin glass sheet.
3. Observation — The needle's deflection shows no appreciable change with any material inserted.
Conclusion: The magnetic effect can act through non-magnetic materials like wood, plastic and glass.

Introduction: Reshma set up several fun magnet activities at her school fair for everyone.
Key Points:
1. Magnetic garland — Magnets can hold objects together to form an attractive magnetic garland.
2. Maze game — Steel balls are guided through a maze by moving a magnet below the cardboard tray.
3. Paperclip rescue — A steel paperclip fallen in water is picked out using a magnet, staying dry.
Conclusion: These games show magnets can move steel objects without even touching them.

Introduction: Repulsion between like poles is the sure test that separates magnets from plain iron.
Key Points:
1. Test pairs — Bring the ends of any two bars close together in different orientations.
2. Repulsion proves magnets — If two bars repel each other, both must be magnets; iron never repels.
3. Attraction is unclear — A magnet always attracts iron, so attraction alone cannot identify the magnet.
Conclusion: The two bars that show repulsion with each other are the magnets; the third is iron.

Introduction: The rules of like and unlike poles help find the poles of an unmarked magnet.
Key Points:
1. Bring marked North pole — Bring the marked magnet's North pole near one end of the unmarked magnet.
2. Repulsion means North — If that end moves away, it is a North pole, since like poles repel.
3. Attraction means South — If that end attracts, it is a South pole, since unlike poles attract.
Conclusion: The unmarked magnet's other end is automatically the opposite pole.

Introduction: A freely suspended magnet itself points along the north-south direction.
Key Points:
1. Suspend freely — Tie a thread to the magnet's middle and let it hang, balanced horizontally.
2. Let it rest — Rotate it gently and wait; it always comes to rest along north-south.
3. Identify north — Knowing sunrise direction as East, find north; the end pointing north is the North pole.
Conclusion: The Earth's giant magnet makes the suspended magnet's north end point northwards.

Introduction: Since the Earth behaves like a giant magnet, a compass reveals its magnetic poles.
Key Points:
1. Compass observation — The compass needle's North pole always points towards the geographic North.
2. Unlike poles attract — Being attracted, the Earth's magnetic pole near geographic North is a South pole.
3. The opposite pole — Similarly, the Earth's magnetic pole near geographic South is a North pole.
Conclusion: A compass shows the Earth's magnet has its South-type pole near the geographic North.

Introduction: Magnetism offers a simple solution to the mechanic's problem of falling screws.
Key Points:
1. Magnetise the screwdriver — Rub a magnet along the screwdriver's length repeatedly in one direction.
2. How it works — The screwdriver becomes a magnet and attracts the steel screws firmly.
3. The result — Screws stick to the screwdriver tip and no longer fall down during repair work.
Conclusion: A magnetised screwdriver holds steel screws firmly, solving the mechanic's problem.

(a) Magnetic materials are materials attracted towards a magnet. Examples: iron, nickel, cobalt. (b) Non-magnetic materials are materials not attracted towards a magnet. Examples: wood, plastic, rubber, glass. (c) The iron nail and the nickel coin will stick to the magnet because iron and nickel are magnetic materials. The pencil (wood) and the glass marble are non-magnetic and will not stick.

(a) A freely suspended magnet comes to rest along the north-south direction. (b) The two poles are the North pole (the end pointing towards the north) and the South pole (the end pointing towards the south). (c) The magnet rests this way because the Earth itself behaves like a giant magnet. To test a metal piece: suspend it freely — if it always comes to rest along the north-south direction, it is a magnet; if it can rest in any direction (like an ordinary iron bar), it is not a magnet.

(a) A magnetic compass is a device for finding directions, developed in olden days. (b) The needle (a magnet) is mounted on a pin standing on the bottom of the box, balanced so it can rotate freely. (c) Structure: a small circular box with a transparent cover; the needle rotates freely on a pin; the North-resting end is painted red; a dial with directions is marked below the needle. To use: keep the compass at the place where directions are needed; wait for the needle to come to rest in the north-south direction; gently rotate the compass box until the north and south marked on the dial align with the needle; now all directions at that place are as indicated on the dial.

(a) Unlike poles (North of one, South of another) attract each other. (b) Like poles (North-North or South-South) repel each other. (c) When an iron bar is brought near a magnet, both its ends are attracted by both the North and South poles — attraction happens with both magnetic and non-magnetised iron. But repulsion happens only when two like poles of two magnets face each other. Since only a magnet can repel another magnet, repulsion is the sure test for identifying a magnet.

(a) This activity is about making an iron sewing needle a magnet by stroking it with a bar magnet. (b) Bring some iron filings or steel pins near the needle — if they get attracted to the needle, it has become a magnet. (c) Pass the magnetised needle through the cork horizontally. Float the cork in a glass bowl of water, keeping the needle above the water level. When the needle comes to rest, it points north-south — the compass is ready. It works because rotating the cork gently and letting it settle again always brings the needle back to the same north-south direction.

(a) Reshma has three identical metal bars — two are magnets and one is just iron — and needs to identify which two are magnets. (b) Attraction alone cannot identify the magnets because the iron bar is also attracted by both poles of either magnet, just like the magnets attract each other at unlike poles. (c) She can bring the bars close to each other in different pairs. Only two magnets show repulsion when like poles face each other. The iron bar will always be attracted (never repelled) by either end of a magnet. The pair that shows repulsion are the two magnets; the bar that never repels is the iron piece. Repulsion is the sure test.

(a) The steel screws kept falling down from the screwdriver while the mechanic was repairing a gadget. (b) Steel is a magnetic material — it is attracted towards a magnet and can be magnetised. (c) The mechanic should magnetise the screwdriver by rubbing it with a magnet (stroking it repeatedly in one direction, like magnetising a needle). Once the screwdriver becomes a magnet, it will hold the steel screws by magnetic attraction, and they will not fall.

(a) The compass needle moves away — like poles repel. (b) The compass needle moves closer — unlike poles attract. (c) There is no appreciable change in the deflection of the needle when wood, cardboard, plastic, or glass is placed between the magnet and the compass. This proves that the magnetic effect can act through non-magnetic materials — non-magnetic materials do not block magnetism.

(a) Magnet X does not move down because like poles of magnets X and Y are facing each other and repelling — the repulsive force balances gravity. (b) This shows that the ring magnets are arranged with like poles facing each other, and like poles repel. (c) To bring X in contact with Y, turn magnet X around (or flip it) so that unlike poles face each other — the unlike poles will attract and X will move down towards Y on its own, without pushing.

(a) Magnets should be stored in pairs with unlike poles on the same side, with a piece of wood in between, and two pieces of soft iron across the ends. (b) Do not heat, drop, or hammer magnets; do not keep them near mobile phones or remote controls. (c) Heating, dropping, or hammering can disturb the arrangement inside the magnet that gives it magnetism, weakening or destroying its magnetic power. Mobile phones and remote controls contain electronic components and can be damaged or malfunction due to the magnet's magnetic effect, so magnets must be kept away from them.

Introduction: Magnets are objects that attract certain materials like iron, and they come in many types.
Key Points:
1. Natural magnets — Naturally occurring magnets, called lodestones, were discovered in ancient times.
2. Artificial magnets — Magnets made from iron pieces and other materials; laboratory and toy magnets are artificial.
3. Shapes of magnets — Magnets are made in different shapes like bar, U-shaped and ring magnets.
4. Everyday uses — Pencil boxes and purses use magnets to keep them closed.
5. More uses — Magnetic compasses find directions, and writing board dusters stick using magnets.
Conclusion: From lodestones to shaped artificial magnets, magnets serve many everyday purposes.

Introduction: Every magnet has two poles where its magnetic strength is concentrated.
Key Points:
1. Two poles — A magnet has two ends called the North pole and the South pole.
2. Iron filings activity — Maximum iron filings stick near the ends; very few stick at the remaining part.
3. True for all shapes — Most iron filings stick to the poles of a magnet of any shape.
4. Breaking a magnet — If broken into pieces, each piece, however small, has both North and South poles.
5. No single pole — A single North pole or South pole can never exist; poles always exist in pairs.
Conclusion: Poles in pairs are a fundamental property of every magnet, whatever its size or shape.

Introduction: A magnetic compass is a small device that indicates directions using a magnetised needle.
Key Points:
1. Structure — It is a small circular box with a transparent cover on it.
2. The needle — A magnetised needle is mounted on a pin, rotating freely on the box's bottom.
3. Markings — The needle's North-pointing end is usually painted red; a dial below shows directions.
4. Working — The needle comes to rest along the north-south direction after some time.
5. Using it — Rotate the box gently until the dial's north aligns with the needle; all directions are then indicated.
Conclusion: The compass works because the Earth's giant magnet makes its needle rest north-south.

Introduction: Magnets follow clear rules of attraction and repulsion based on their poles.
Key Points:
1. Unlike poles attract — The North pole of one magnet attracts the South pole of another magnet.
2. Like poles repel — North-North or South-South poles of two magnets push each other away.
3. Iron always attracts — Both magnet poles attract an iron bar at both its ends, unlike magnets.
4. Sure test — Only repulsion proves both pieces are magnets; attraction may just involve iron.
5. Compass activity — A magnet's North pole deflects the compass needle's North pole away; its South pole attracts it closer.
Conclusion: Repulsion is the sure test of magnetism because iron never repels a magnet.

Introduction: A homemade magnetic compass needs only a needle, cork, magnet, bowl and water.
Key Points:
1. Magnetising the needle — Stroke a sewing needle with one magnet pole along its length 30–40 times.
2. Checking magnetism — Bring iron filings near; attraction confirms the needle has become a magnet.
3. Making it float — Pass the needle horizontally through a cork and float it on a bowl of water.
4. Observing rest — The needle comes to rest pointing along the north-south direction.
5. The science — The Earth behaves like a giant magnet, forcing the magnetised needle north-south.
Conclusion: Rotating the cork repeatedly shows the needle always points in the same direction.

Introduction: An activity tests whether materials placed between a magnet and compass affect the magnetic effect.
Key Points:
1. Base observation — Bring a bar magnet's North pole near a compass needle and watch its deflection.
2. Adding wood — Place a piece of wood between the magnet and the compass needle.
3. Adding more materials — Repeat with a cardboard sheet, thin plastic sheet and thin glass sheet.
4. Observations — The needle's deflection shows no appreciable change with any material inserted.
5. Conclusion — The magnetic effect can act through non-magnetic materials like wood, cardboard, plastic and glass.
Conclusion: This is why a magnet can attract objects through paper, plastic or glass sheets.

Introduction: Reshma's story naturally leads from a navigation problem to the world of magnets.
Key Points:
1. The story problem — Sailors in her story lost directions when storm clouds hid the stars.
2. Finding the answer — She researched and learnt that sailors used the magnetic compass for directions.
3. Everyday examples — Pencil boxes and purses have magnets that keep them closed.
4. School example — The writing board's duster in her school also had a magnet attached.
5. Curiosity sparked — These examples made Reshma curious to explore magnets further.
Conclusion: The story shows how a real problem introduces us to the useful world of magnets.

Introduction: This chapter teaches several important properties that all magnets share.
Key Points:
1. Two poles — Every magnet has a North pole and a South pole at its two ends.
2. Poles in pairs — Breaking a magnet gives smaller magnets; a single isolated pole cannot exist.
3. Attract magnetic materials — Magnets attract iron, nickel, cobalt and some of their combinations.
4. Direction finding — A freely suspended magnet always rests along the north-south direction.
5. Attraction and repulsion — Unlike poles attract each other, while like poles repel each other.
Conclusion: These properties explain compasses, magnet games and the careful storage of magnets.

Introduction: Magnets must be handled carefully or they may lose their magnetism.
Key Points:
1. Store in pairs — Keep magnets in pairs with unlike poles on the same side.
2. Separators and keepers — Place a wooden piece between them and soft iron pieces across the ends.
3. No heat or hammering — Never heat, drop or hammer a magnet, as this weakens its magnetism.
4. Keep away from devices — Do not keep magnets near mobile phones or remote controls.
5. The reason — Careless handling disturbs the magnet's internal arrangement, reducing its strength.
Conclusion: Proper storage and gentle handling keep magnets strong and safe for long use.

Introduction: Knowledge of magnets helps us in finding directions, closing things and doing tricks.
Key Points:
1. Finding directions — Magnetic compasses, based on freely suspended magnets, guide travellers and sailors.
2. Closing objects — Pencil boxes and purses use magnets to keep their lids closed firmly.
3. Holding objects — Writing board dusters stick to boards because of attached magnets.
4. Lifting steel items — Magnets pick up steel clips and pins, even from water, without touching.
5. Repair work — A magnetised screwdriver holds steel screws, preventing them from falling.
Conclusion: Understanding magnet properties makes many everyday tasks simple, safe and fun.