Selina Concise Solutions for ICSE Class 6 Physics Chapter 6 Magnetism

Synposis

• The first natural magnet was discovered in Magnesia, a town in Greece. It was called the lodestone.
• Artificial magnets are made of iron or steel. They are made of different shapes namely the bar magnet, cylindrical magnet, U-shaped magnet, horse-shoe magnet, magnetic needle and compass.
• The materials which are attracted by a magnet are called magnetic materials. Examples: iron, steel, cobalt.
• The materials which are not attracted by a magnet are called non-magnetic materials. Examples: paper, wood, brass, plastic, copper aluminium, etc.
• A magnet has two poles, a north and a south pole.
• A magnet has the following properties:
  - A magnet attracts the small pieces of iron.
  - A magnet always rests in the north-south direction, if it is free to swing.
  - Like poles repel each other and unlike poles attract each other.
  - Poles always exist in pairs, cannot be isolated.
• Magnets are used to separate iron and steel from their mixture with non-magnetic substances. -
• Magnets are used in many electrical appliances such as electric . bell, loud-speaker, etc.
• A magnetic compass is used by sailors and navigators to find the north-south direction.
• Magnetic induction is the process in which a piece of iron temporarily behaves like a magnet in the presence of another magnet.
• When a magnet is placed near an iron piece, the iron piece behaves like a magnet. The end of the iron piece near the north pole of the magnet becomes a south pole while the farther end becomes a north pole.
• It is because of magnetic induction that a magnet attracts a piece of iron.
• An iron piece can be made into a magnet by any of the following methods:
  - Magnetic induction
  - Single touch method
  - Double touch method
  - Electrical method
• In the single touch method, we need a single magnet, but in the double touch method we need two magnets, hi these methods, the end touched last by the magnet has the polarity opposite to that of the striking pole.
• Powerful magnets are made by the electrical method.
• Electromagnets or temporary magnets are made of soft iron.
• Permanent magnets are made of steel.
• Electromagnets are used in devices like electric bell, magnetic toys, telephone etc.
• Permanent magnets are used in devices like galvanometer, ammeter, voltmeter etc.
• A magnet can be destroyed by rough handling, by dropping it several tunes, by hammering it repeatedly and by heating it.
• The magnetic field around a magnet is the space in which a magnetic substance such as small iron piece experiences a force of attraction.
• The earth itself behaves like a magnet. It has its own magnetic field.
• The south polarity of the earth is near the geographic north pole and the north polarity of the earth is near the geographic south pole.
• Magnetic keepers are used to store the magnets.
• Magnetic keepers are small pieces of soft iron.

ACTIVITY 1
Magnetic objects
Iron, Steel, Cobalt, Nickel
Non-magnetic objects
Wood, Stone Plastic, Rubber Copper, Sand, Gold, Silver, Brass Paper, Aluminium

Test yourself

A. Objective Questions

1. Write true or false for each statement.

(a) Artificial magnets are weaker than the natural magnets.
Answer: False
Artificial magnets are stronger than the natural magnets.
Artificial magnets are specifically engineered to have high magnetic strength for industrial and scientific use. Natural magnets like lodestone are generally quite weak and irregular in their properties.
Teacher's Tip: Remember "Man-made is Mighty" - artificial magnets can lift huge scrap metal!
Exam Tip: Always provide the corrected statement to earn full marks for a "False" answer.

(b) Poles of a magnet cannot be separated.
Answer: True
Magnetism always exists in dipoles, meaning a north pole must always have a corresponding south pole. Even if you break a magnet in half, new poles will instantly form at the broken ends.
Teacher's Tip: Think of a magnet like a coin; you cannot have a coin with only one side.
Exam Tip: Use the term "dipoles" to describe why poles cannot be isolated.

(c) A magnet can attract only a magnetic substance.
Answer: True
Magnets exert force only on specific materials like iron, nickel, and cobalt which have magnetic domains that can align. Non-magnetic materials like wood or plastic do not respond to magnetic fields at all.
Teacher's Tip: Use the "INC" rule - Iron, Nickel, and Cobalt are the materials that stick!
Exam Tip: If asked to explain, mention that non-magnetic substances lack the required atomic structure for attraction.

(d) A magnet has no effect when it is heated to a high temperature.
Answer: False.
A magnet get demagnetised when it is heated to a very high temperature.
High heat causes the atoms in a magnet to vibrate violently, which disrupts the alignment of its magnetic domains. Once the internal alignment is lost, the material loses its magnetic properties.
Teacher's Tip: Heat "scrambles" the internal tiny magnets inside the metal.
Exam Tip: Mention "demagnetization" as the specific result of heating a magnet.

(e) Permanent magnets get easily demagnetised.
Answer: False.
Permanent magnets cannot be demagnetised.
While they can be demagnetized by extreme conditions like very high heat or heavy hammering, they are designed to retain their magnetism for a very long time. This is why they are called "permanent" compared to temporary magnets like electromagnets.
Teacher's Tip: Permanent magnets are made of steel which "holds" its magnetism tightly.
Exam Tip: Be careful with the word "easily"; permanent magnets are actually very resistant to losing their power.

(f) Magnetic poles occur in pairs.
Answer: True
Every magnet has two ends called the North and South poles that always exist together. This is a fundamental law of physics called Gauss's Law for Magnetism.
Teacher's Tip: Remember the "Magnetic Twin" rule - North and South are never alone.
Exam Tip: Mention that a "monopole" (single pole) has never been found in nature.

(g) Single touch method is better than the electrical method for making a magnet.
Answer: False.
Electrical method is better than single touch method.
The electrical method produces much stronger and more reliable magnets by using the power of electric current. Single touch method is a manual process that often results in weaker magnetism.
Teacher's Tip: Electricity provides "Stronger Strokes" than a hand-held magnet ever could.
Exam Tip: Identify the electrical method as the most efficient way to create powerful magnets.

(h) Magnetic keeper is a wooden piece.
Answer: False.
Magnetic keepers are the pieces of soft iron.
Keepers are made of soft iron because they provide a complete path for the magnetic field lines to follow. This prevents the magnet from "leaking" its strength and becoming demagnetized over time.
Teacher's Tip: Keepers are the "Safe Boxes" for magnetic energy.
Exam Tip: Specify "soft iron" as the material to ensure full marks.

(i) Copper cannot be magnetised.
Answer: True
Copper is a non-magnetic material because its atoms do not have permanent magnetic moments that can be aligned. Only ferromagnetic materials like iron can be turned into magnets.
Teacher's Tip: Copper is a great conductor of electricity but a poor friend to magnets.
Exam Tip: Categorize copper as "non-magnetic" in any classification list.

2. Fill in the blanks

(a) Temporary magnets are usually made up of soft iron.
Answer: soft iron.
Soft iron is used because it magnetizes quickly when a field is present but loses that magnetism almost immediately when the field is removed. This makes it perfect for devices like electric bells.
Teacher's Tip: Soft iron = Soon On, Soon Off.
Exam Tip: Always specify "soft" iron rather than just "iron" for temporary magnets.

(b) Rough handling destroys the magnetic properties of a magnet.
Answer: magnetic.
Dropping or hitting a magnet causes physical shock that misaligns the tiny molecular magnets inside. Over time, this cumulative damage will turn a strong magnet into an ordinary piece of metal.
Teacher's Tip: Treat magnets like eggs - handle them with care to keep them strong!
Exam Tip: List "hammering" and "dropping" as examples of rough handling.

(c) Like poles repel each other.
Answer: repel.
When two North poles or two South poles are brought together, they push away from one another. This is one of the most basic rules of magnetic interaction.
Teacher's Tip: Like poles are like "Grumpy Twins" - they don't want to be near each other.
Exam Tip: Remember: Like = Repel, Unlike = Attract.

(d) A freely suspended magnet points in the north-south direction.
Answer: north-south.
A magnet aligns itself with the Earth's magnetic field, which runs between the poles. This property is what allows us to use a magnetic compass for navigation.
Teacher's Tip: Suspended magnets act like "Directional Signs" for the Earth.
Exam Tip: Use this to explain the "Directive Property" of magnets.

(e) In a magnet, ends have the maximum attractive property.
Answer: ends.
The magnetic field lines are most concentrated at the tips of the magnet, which are called the poles. Consequently, the pulling force is significantly stronger at the ends than in the middle.
Teacher's Tip: If you want to lift something, use the "Tips" of the magnet.
Exam Tip: Use the term "poles" synonymously with "ends" for high marks.

(f) A magnet has two poles.
Answer: two.
Regardless of its size or shape, a magnet will always have exactly one North pole and one South pole. Even microscopic magnets still follow this two-pole rule.
Teacher's Tip: A magnet is always a "Two-Pole Team."
Exam Tip: Identify the poles as "North seeking" and "South seeking."

3. Match the following
Column A
(a) Steel
(b) Soft iron
(c) Use in electric bell
(d) Magnetic keepers

Column B
(i) to store magnets
(ii) temporary magnet
(iii) permanent magnet
(iv) electromagnet

Answer:
(a) Steel - (iii) permanent magnet
(b) Soft iron - (ii) temporary magnet
(c) Use in electric bell - (iv) electromagnet
(d) Magnetic keepers - (i) to store magnets
Steel is used for permanent magnets because it retains its magnetic domains once aligned. Soft iron is the core of an electromagnet because it can be turned on and off easily.
Teacher's Tip: Steel stays strong; Soft iron is for speed.
Exam Tip: Match the material to its specific magnetic longevity.

4. Select the correct answer

(a) If we suspend a magnet freely, it will settle in .
1. east-west direction
2. north-south direction
3. north-east direction
4. east-south direction
Answer: 2. north-south direction
The magnet aligns itself with the Earth's natural magnetic field lines. The north pole of the magnet will point towards the geographic North Pole of the Earth.
Teacher's Tip: A hanging magnet is just a "Big Compass."
Exam Tip: This is called the "Directive Property" of a magnet.

(b) Making a magnetic substance a magnet by bringing it closer to another magnet without touching it, is
1. magnetic induction method
2. single touch method
3. double touch method
4. electrical method
Answer: 1. magnetic induction method
Induction happens when the magnetic field of a strong magnet forces the domains of a nearby iron piece to align. This magnetism is usually temporary and disappears once the strong magnet is moved away.
Teacher's Tip: Induction is like "Magnetism through the Air."
Exam Tip: The key phrase is "without touching," which defines induction.

(c) An example of natural magnet is
1. iron
2. steel
3. lodestone
4. none of above
Answer: 3. lodestone
Lodestone is a naturally occurring magnetic mineral called magnetite. It was the very first substance humans used to understand the principles of magnetism.
Teacher's Tip: Lodestone is the "Nature's Original Magnet."
Exam Tip: "Magnetite" is the scientific name for the mineral in lodestone.

(d) The artificial magnet used to detect direction in the laboratory is
1. U-shaped magnet
2. horse shoe magnet
3. electromagnet
4. magnetic compass
Answer: 4. magnetic compass
A compass contains a very light, magnetized needle that rotates freely to point North. This makes it the standard tool for finding directions in experiments and navigation.
Teacher's Tip: If you're lost, follow the "Compass Core."
Exam Tip: Mention that the compass needle is itself a small magnet.

B. Short/Long Answer Questions

Question 1: What is a magnet ?
Answer: The substances which have the property of attracting iron, are called magnets.
Magnets possess a magnetic field that exerts a force on ferromagnetic materials. This invisible force can either pull objects toward the magnet or push other magnets away.
Teacher's Tip: A magnet is an "Iron-Attractor."
Exam Tip: A complete definition should mention that magnets also have two poles.

Question 2: What are magnetic and non-magnetic substances ? Give two examples of each.
Answer: Magnetic substances: The substances that get attracted by a magnet are called magnetic substances. Iron, steel, cobalt and nickel are magnetic substance.
Non-magnetic substances : The substances that do not get attracted by a magnet are called non-magnetic substances, e.g., wood, plastic, copper, paper, aluminum, rubber, stone.
The difference lies in the internal atomic structure; magnetic substances have domains that can align with an external magnetic field. Non-magnetic substances have a structure that does not respond to these fields.
Teacher's Tip: Use "S-I-N-C" for Magnetic: Steel, Iron, Nickel, Cobalt.
Exam Tip: When asked for examples, always list distinct materials like metal vs wood.

Question 3: What are natural and artificial magnets ?
Answer: Natural magnets: Natural magnets are those which are found in nature e.g. load stone.
Artificial magnets: Man made magnets are called artificial magnets, e.g. electromagnet.
Natural magnets are weak and have irregular shapes because they are found in rocks. Artificial magnets are created by humans to be very strong and come in specific shapes like bars or rings.
Teacher's Tip: Natural = Earth's Rocks; Artificial = Factory-Made.
Exam Tip: Provide "Lodestone" as the classic example for natural magnets.

Question 4: How is an artificial magnet prepared from a natural magnet ?
Answer: Pieces of iron or other materials are made magnets by rubbing them with natural magnets (or by passing direct current through a wire wound around them). This is how artificial magnets are made.
When you rub iron with a magnet, the friction and magnetic field help align the iron's internal domains. This "transfers" magnetic properties to the previously non-magnetic iron piece.
Teacher's Tip: It's like "sharing" magnetism through rubbing.
Exam Tip: Mention both rubbing and electrical methods for a complete answer.

Question 5: State two ways of magnetising an iron piece.
Answer: The two ways of magnetising an iron piece are:
1. Magnetic induction method. Take a long iron nail and test it for magnetic properties by bringing near the magnetic substances. You will see nail does not attract the magnetic substances. Now bring near a pole of a bar magnet to the head of the nail. Now bring the iron paper clips near the pointed end of the nail, you will observe that the iron paper clips now get attracted towards the nail. This is because iron nail has become magnet. Now take the bar magnet away form the iron nail, paper clips fall off. This magnetism is temporary.
2. Single touch method: Take a demagnetised piece of iron. Place it on a table surface. Take a magnet and select its one pole. Now mb it with the selected pole on the iron in one direction for several times. After sometime, the iron piece turns into a magnet.
These methods show how a magnetic field can reorganize the internal particles of iron. While induction is usually temporary, the single touch method creates a more lasting effect.
Teacher's Tip: Use "Induction" for temporary magic and "Touching" for longer-lasting magnets.
Exam Tip: Always mention that in "Single touch," you must rub in only ONE direction.

Question 6: How can magnetic properties of a magnet be destroyed ?
Answer: 1. By hammering the magnet repeatedly. 2. By rough handling 3. By heating.
Physical or thermal energy disrupts the organized alignment of magnetic domains within the metal. Once the domains point in random directions, the overall magnetic effect cancels out.
Teacher's Tip: Heat and Hits are the "Enemies" of magnets.
Exam Tip: If asked for three ways, include heating to "red hot" as it's the most effective way.

Question 7: Why docs a freely suspended magnet always rest in north- south direction ?
Answer: A freely suspended magnet always rest in north-south direction because the north-pole of the magnet lies in the geographic north direction and the south pole of the magnet lies in the geographic south direction. So it aligns itself in N-S direction. As unlike poles attract and like poles repel.
The Earth itself acts as a giant bar magnet with its own magnetic field lines wrapping around the planet. A small hanging magnet is forced to follow these lines, acting like a compass needle.
Teacher's Tip: Earth is the "Big Magnet" that controls all small magnets!
Exam Tip: Explain that this happens due to the interaction with "Earth's Magnetic Field."

Question 8: Draw diagrams of the artificial magnets of four different shapes.
Answer: [Diagrams showing Bar Magnet, Cylindrical Magnet, U-Shaped Magnet, and Horse Shoe Magnet]
Artificial magnets are designed in these shapes to maximize their usefulness in various machines and tools. For example, the Horse Shoe shape brings the two poles close together to create a very strong concentrated field.
Teacher's Tip: Each shape has a specific "Job" in the world of tools.
Exam Tip: Label the North (N) and South (S) poles on every diagram you draw.

Question 9: Why are the artificial magnets preferred over the natural magnets ?
Answer: Artificial magnets are preferred over natural magnets because natural magnets are weak and often irregular in shape, they can readily be magnetised and demagnetised by turning the current on or off in the coil.
Artificial magnets can also be made much stronger and shaped to fit exactly inside electronic devices like phones and speakers. This flexibility makes them essential for modern technology where natural magnets would be too weak.
Teacher's Tip: Artificial magnets are "Custom-Made" for our needs.
Exam Tip: Mention "controllable strength" as a key advantage of artificial electromagnets.

Question 10: Describe an experiment to show that the maximum attractive property is at the poles of a magnet.
Answer: Take a bar magnet and place a steel pin at some distance. We observe that nothing happens. Now, bring the steel pin near the pole of the bar magnet. We notice that pin sticks to the magnet. This experiment shows that maximum magnetic force acts at the poles of the magnet.
If you dip a magnet into iron filings, you will see a large cluster of filings at the ends but almost none in the middle. This visual proof confirms that the magnetic field is densest at the poles.
Teacher's Tip: The poles are the "Hotspots" of magnetism.
Exam Tip: Use the term "magnetic poles" to describe the ends where attraction is strongest.

Question 11: State four important properties of a bar magnet.
Answer: 1. Attractive property: A magnet can attract small pieces of iron filing or other ferromagnetic materials. 2. Directive property: If a magnet is suspended horizontally by a thin thread (say silk thread), it rests always pointing north- south direction of earth. 3. Like poles always repel each other and unlike poles attract each other. 4. Poles always exist in pairs : Single pole can never exist.
These properties define how magnets interact with the world and other magnets. They are used in everything from simple compasses to complex medical MRI machines.
Teacher's Tip: Remember the "Big Four": Attraction, Direction, Pairs, and Polarity Rules.
Exam Tip: List these properties as distinct points to make them easy for the examiner to grade.

Question 12: Explain the attractive property of a magnet with the help of an experiment.
Answer: Take iron filling on a piece of paper. Bring a bar magnet near it. Iron filling will cling to it. It shows the attractive property of magnet.
The magnetic field extends outward from the magnet and pulls the iron filings toward it. This attraction happens without physical contact, proving it is a "non-contact force."
Teacher's Tip: Attraction is the "Pulling Power" of a magnet.
Exam Tip: Specify that it only attracts "magnetic substances" like iron.

Question 13: Describe the method by which an iron bar can be made a magnet.
Answer: Single touch method : Place the iron bar (or the needle) AB on a table. Take a bar magnet NS and place it almost vertical with its north pole (N) on the end A of the bar. Move the magnet along tire iron bar till the other end B is reached. Lift the magnet at the end B and again place it on the first end A Again stroke the bar. Repeat the process about 20 times. Then turn the iron bar AB upside down. Again stroke it with the magnet about 20 times. The bar now becomes a magnet.
By rubbing the magnet in a single direction, you force the tiny internal magnetic particles of the iron bar to all face the same way. When they are aligned, their small magnetic fields add up to make the whole bar a magnet.
Teacher's Tip: It's like combing your hair—you must go in one direction to make it neat!
Exam Tip: Always emphasize "lifting the magnet" and "single direction" in your description.

Question 14: How are the magnets kept safely ? What is the role of keepers in storing the magnets ?
Answer: When magnets are not in use they should be kept and stored in magnetic keepers. The magnetic keeper are the pieces of soft iron. A magnetic keeper has a card board with one or two iron soft pieces. Two magnets are placed in such a way that their opposite poles are close to each other and then a soft iron keeper is attached with it.
The keepers create a "loop" for the magnetic field lines, keeping them confined within the iron instead of spreading into the air. This helps the magnet maintain its internal domain alignment and prevents it from becoming weak.
Teacher's Tip: Keepers are "Magnetic Glue" that holds the strength inside.
Exam Tip: Mention that magnets should be stored in "pairs with opposite poles" for best results.

Question 15: Define the term magnetic field of a magnet. How will you recognise it experimentally ?
Answer: The space around a magnet in which if a magnetic substance such as small pieces of iron, are placed, they get attracted to-wards the magnet, is called the magnetic field. Recognition of the magnetic field around a magnet: If a magnet is placed below a sheet of stiff paper and some iron filings are spread on it, then on tapping the sheet gently, the iron filings are found to arrange themselves in a definite pattern as shown in fig.
The field is an invisible zone of influence that gets weaker as you move further away from the magnet. The pattern formed by the iron filings allows us to see the shape and direction of this invisible force.
Teacher's Tip: The field is like a "Magnetic Force-Field" you see in movies.
Exam Tip: Mention that field lines "start at the North pole and end at the South pole" for extra detail.

Question 16: How will you make an iron bar electromagnet ? Draw a diagram showing the polarities of the electromagnet.
Answer: Take the given iron bar AB. Wound several turns of insulated copper wire over the bar. Connect the ends of the wire to a battery through a switch. Press the switch to pass current. After some time, the bar AB becomes a magnet. The end A of the bar at which the current enters the coil in clockwise direction becomes the south pole (S) and the end B of the bar at which the current leaves the coil in anti-clockwise direction becomes the north pole (N).
An electromagnet is highly useful because you can control its strength by changing the current. Once you turn off the electricity, the magnetic domains in the soft iron core return to their random states and the magnetism disappears.
Teacher's Tip: Electricity + Iron Coil = Instant Magnet!
Exam Tip: Use the "Clock Rule" to identify the poles in your diagram.

Question 17: State two ways of increasing the strength of an electro Magnet
Answer: Strength of the electromagnet: The strength of the electromag net can be increased: 1. by increasing the current in the coil, and 2. by increasing the total number of turns of the coil.
Adding more turns of wire or pushing more electrical power through the circuit concentrates the magnetic field in the center of the coil. This makes the iron core much more effective at attracting other objects.
Teacher's Tip: More "Turns" and more "Amps" equals more "Muscle" for the magnet.
Exam Tip: List both "current" and "turns" as distinct factors for a full-score answer.

Question 18: Suppose you are given a long bar magnet and you are asked to break it into four small magnets. Draw diagrams showing the polarities of each broken part.
Answer: [Diagram showing a bar magnet broken into four pieces, each with N and S poles]
When you break a magnet, the alignment of the domains inside is still present in the pieces. Therefore, the broken edge of the piece that was near the original North pole will instantly become a new South pole.
Teacher's Tip: Every piece is a "Mini-Me" of the original magnet.
Exam Tip: Make sure each of your four pieces has both an N and an S label.

Question 19: State three important uses of a magnet.
Answer: Use of magnet: 1. Magnets are used in magnetic compass, door bells, refrigerators. 2. Magnets are used in dynamos, motors, loudspeakers, microphones etc. 3. Ceramic magnets are used in computers. 4. Magnets are used in toys to give magic effect.
Magnets are the hidden heroes of modern life, allowing motors to spin and speakers to produce sound. Without them, we wouldn't have reliable electricity or the ability to store digital information on hard drives.
Teacher's Tip: Look at your fridge—there's a magnet at work right there!
Exam Tip: Providing distinct categories (Communication, Appliances, Navigation) shows a better understanding.

Question 20: What is magnetic induction ? Explain with the help of a diagram.
Answer: Magnetic Induction: The property by which an ordinary piece of iron acquires magnetic properties temporarily due to the presence of another magnet close to it, is known as magnetic induction. Take a long nail. Put it on the arm of a stand. Spread some iron pins on the base of stand. You will find that the pins do not get attracted towards the nail. Now touch a magnet at the end of nail. As the end is brought close to the head of nail, some pins cling to the nail. It happens because the nail turns into magnet and acquires the properties of magnetism. The moment you remove the magnet from the head of the nail. The pins will fall down. It will no more be a magnet.
Induction proves that magnetism can "travel" or influence nearby metals through their surrounding fields. It is a temporary state, showing that iron only acts as a magnet when a strong external force organizes its particles.
Teacher's Tip: Induction is like "Magnetism by Proximity."
Exam Tip: Always describe the "after" effect—the pins falling off—to prove it is temporary.

Question 21: In which direction does a suspended bar magnet come to rest? Give reason.
Answer: A magnet always rests in North and South direction, i.e. N-end always towards North of Earth and S-end towards South of Earth.
This happens because the Earth itself acts as a massive magnet with its own magnetic poles. The suspended magnet's poles are attracted to the Earth's opposite magnetic poles, keeping it locked in a North-South line.
Teacher's Tip: The Earth is the "World's Largest Magnet."
Exam Tip: State that the "Earth's Magnetic Field" is the primary reason for this alignment.

Question 22: State three differences between the temporary and permanent magnets.
Answer: Temporary magnet: 1. It is made up of soft iron. 2. The magnet which loses its magnetism as soon as magnetising force is removed away from it. 3. Because of its weak power, it is not used to make iron piece into magnet.
Permanent magnets: 1. It is made up of steel, cobalt and nickel. 2. The magnet, which does not lose its magnetic properties easily is called permanent magnet. 3. It can convert ordinary piece of iron into a temporary magnet.
The core difference is "retentivity," or how well a material holds on to its magnetism. Steel is stubborn and keeps it, while soft iron is easy-going and lets it go quickly.
Teacher's Tip: Steel = Strong & Stable; Soft Iron = Short-term.
Exam Tip: Use a table to highlight these differences side-by-side.

Question 23: State three ways of demagnetising a magnet.
Answer: A magnet can be demagnetized in the following ways: 1. rough handling 2. hammering the magnet several times. 3. passing an alternating current around the magnet. 4. dropping the magnet on the floor several times. 5. heating the magnet to a very high temperature.
All these methods work by giving the atoms enough energy or shock to "break ranks" and lose their orderly alignment. Once the internal structure is chaotic again, the magnetic field disappears.
Teacher's Tip: Hits, Heat, and AC current are the three "Magnethunters."
Exam Tip: Be specific; "heating to redness" is the most scientific way to describe the thermal method.

Question 24: Suggest one way to recognise the magnetic field of the earth.
Answer: If we suspend a magnet such that it is free to swing, we see that it always rests in the north-south direction. The north pole of the magnet lies in the geographic north direction and the south pole of the magnet lies in the geographic south direction. So it aligns itself in N-S direction.
The fact that every suspended magnet on the planet behaves the same way is proof of a global magnetic influence. This invisible field is always present, guiding compasses and protecting us from solar radiation.
Teacher's Tip: The Earth has an "Invisible Net" of magnetism all around it.
Exam Tip: Use the term "Directive Property" to link the magnet's behavior to Earth's field.

Question 25: Name the material of core of an electromagnet for 1. temporary magnet 2. permanent magnet.
Answer: 1. They are made of soft iron. 2. They are made of iron, steel, cobalt, nickel or an alloy called ANILCO.
ALNICO is a powerful modern alloy made of Aluminum, Nickel, and Cobalt. It is specifically designed to create incredibly strong permanent magnets used in industrial sensors and speakers.
Teacher's Tip: ALNICO = Al + Ni + Co. The name tells you the ingredients!
Exam Tip: Soft iron is always for temporary; Alnico/Steel is for permanent.

Question 26: You are given an iron nail, a torch cell and a long piece of insulated copper wire. With the help of a labelled neat diagram, describe in steps how you will make the nail, an electromagnet.
Answer: Aim : To make an electromagnet. Materials Required : An iron nail, a battery, a switch, some insulated copper wire and some iron paper pins. Procedure : Coil the insulated copper wire around the iron nail. Connect the ends of the wire to the battery through the switch. Close the switch so that electric current flows through the copper wire. Now bring the iron paper pins close to the iron nail. Observation And Conclusion : The paper pins get attracted to the nail, showing that the nail has turned into an electromagnet. Now, if you switch off the current, the iron paper pins will drop off the iron nail.
This experiment demonstrates that magnetism can be "created" using electricity. The flow of electrons through the wire coil creates a field that aligns the domains of the iron nail inside.
Teacher's Tip: This is the "Switchable Magnet" trick.
Exam Tip: Make sure to draw a diagram with a battery, a coil, and a clearly labeled nail.

Question 27: Describe an experiment to illustrate that like poles repel while the unlike poles attract.
Answer: 1. Take two bar magnets A and B. Suspend one magnet A with a silk thread from a support so that it is free to swing. The magnet will come to rest in the north-south direction. The north pole of the magnet is in the north direction and the south pole of the magnet is in the south direction. 2. Now holding the other magnet B in your hand, bring its north pole near the north pole of the suspended magnet A (such that the two magnets do not touch each other) as shown in figure. You will observe that the suspended magnet A moves away from the magnet B. This shows that the like poles repel each other. Now bring the south pole of the magnet B near the north pole of the suspended magnet A as shown in figure, without touching it. You will observe that the magnet A moves towards the magnet B. This shows that the unlike poles attract each other.
This fundamental law of poles is similar to how electric charges behave. It is the core principle used to build magnetic motors and levitation systems like Maglev trains.
Teacher's Tip: Like poles "push" and unlike poles "pull."
Exam Tip: Use the terms "repulsion" and "attraction" clearly in your conclusion.

Question 28: What are magnetic keepers? Name its material.
Answer: Magnetic keepers are used to store the magnets. Magnetic keepers are small pieces .of soft iron.
Keepers help maintain the strength of a magnet by preventing its magnetic field lines from interacting with outside influences. By providing a low-resistance path for the field, they keep the magnet's internal domains properly aligned.
Teacher's Tip: Keepers "Keep" the power from leaking away.
Exam Tip: Identify "soft iron" as the material used for keepers.

Question 29: How are the north and south poles of a magnet located ? Explain.
Answer: Suspend a bar magnet with a silk thread from a wooden stand as shown in figure. The magnet swings for some time and then eventually comes to rest in a particular direction i.e., north-south direction. If we disturb the magnet a little, the magnet again comes to rest in the north-south direction. The end of the magnet which points towards the north is called the north seeking pole or simply the north pole and the end which points towards the south is called the south seeking pole or simply the south pole. The north and south poles are marked by the letters N and S respectively.
This "finding North" behavior is universal for all magnets due to Earth's magnetic field. We name the poles based on the geographical direction they seek out, making them the perfect natural compasses.
Teacher's Tip: North seeking = North pole. South seeking = South pole.
Exam Tip: Mention "freely suspended" as a necessary condition for this experiment to work.

ADDITIONAL QUESTIONS

Check Your Progress
Answer the following.

Question 1: What are magnetic substances ?
Answer: Substances such as iron, nickel, cobalt, or their alloys that get attracted by a magnet are called magnetic substances.
These materials have a special property where their atoms act like tiny magnets that can be grouped together. Only a few elements in the periodic table belong to this special "magnetic club."
Teacher's Tip: Remember the "Magnetic Trio": Iron, Nickel, and Cobalt.
Exam Tip: Mention "alloys" (mixtures of metals) as they can also be magnetic.

Question 2: What are artificial magnets ?
Answer: Magnets that are made by humans from magnetic substances are called artificial magnets. They can be made in different shapes and sizes like bar magnet, horseshoe magnet, etc.
Artificial magnets are much more powerful and useful than natural ones found in the ground. They are the ones we find in everyday objects like speakers, motors, and fridge magnets.
Teacher's Tip: If you bought it at a store, it's an artificial magnet!
Exam Tip: Mention "Steel" as the common material used to make artificial permanent magnets.

Question 3: Why is it not possible to isolate a single magnetic pole?
Answer: Magnetic poles always exist in pairs and cannot exist independently. If a bar magnet is broken into two or more pieces, each of them will have a north pole and a south pole. Hence, it is impossible to obtain a piece of magnet with only one magnetic pole.
Magnetism is created by the way particles move inside a substance, and that motion always creates two sides. Even at the atomic level, every single magnet is a "dual-pole" system.
Teacher's Tip: Breaking a magnet is like breaking a pencil—every small piece still has two ends.
Exam Tip: Use the term "unbreakable pair" to describe magnet poles.

Question 4: Can you bring two similar poles of two different magnetic close together easily? Why?
Answer: No, because like poles repel each other, when two magnetic are brought close to each other.
As you try to push two North poles together, you will feel an invisible force pushing them back with more and more strength. This repulsion is a physical proof of the laws of magnetism.
Teacher's Tip: Like poles are like "Magnets fighting each other."
Exam Tip: Use the word "repulsion" to explain why it is difficult.

Question 5: What is meant by the directional property of magnets ?
Answer: Directional property of magnets states that a freely suspended magnet always points towards the geographical north-south direction. Every magnet, irrespective of its shape, has a north pole and a south pole.
This property is the foundation of navigation, as it allows us to know which way is North even in the middle of the ocean. It works because the magnet acts like a tiny arrow following Earth's massive magnetic field lines.
Teacher's Tip: A hanging magnet is the "Earth's Pointer."
Exam Tip: Mention "Earth's magnetic field" as the cause of this property.

Exercises

A. Tick the most appropriate answer.

1. Temporary magnets are made of
1. soft iron
2. steel
3. stainless steel
4. copper
Answer: 1. soft iron
Soft iron is chosen because its magnetism is easily "switched" on and off. Once the external magnetizing force is gone, the soft iron loses its magnetic field instantly.
Teacher's Tip: Soft iron = "Quick-magnet."
Exam Tip: Contrast this with steel, which is used for *permanent* magnets.

2. The surest test of magnetism is
1. attraction
2. repulsion
3. diffusion
4. hammering
Answer: 2. repulsion
A magnet can attract an ordinary piece of iron, but it can only *repel* another magnet. Therefore, repulsion is the only way to be 100% sure that an object is truly magnetized.
Teacher's Tip: Attraction could be "Magnet vs Iron," but Repulsion is "Magnet vs Magnet!"
Exam Tip: Learn this rule! Repulsion is the "Gold Standard" test for a magnet.

3. Which of the following methods is used to magnetize a magnetic without touching it by a magnet ?
1. Single-touch
2. Double-touch
3. Using electric current
4. None of these
Answer: 3. Using electric current (or Induction if listed, but here 3 is the best match).
An electric current creates a magnetic field around a wire. By placing a metal inside a coil of wire, the metal can be magnetized purely by this field without any physical rubbing.
Teacher's Tip: Electricity is like "Invisible Touching" for magnets.
Exam Tip: The term "electromagnetism" describes this non-contact magnetization.

4. The region around a magnet where its magnetic force can be experienced is called
1. magnetic axis
2. magnetic equator
3. magnetic field
4. magnetic poles
Answer: 3. magnetic field
The field is the "area of influence" where the magnet's power can pull or push other objects. We visualize this using "field lines" that loop from one pole to the other.
Teacher's Tip: Field = "Force-Zone."
Exam Tip: Magnetic force is strongest where the field lines are closest together.

5. A permanent magnet can be demagnetized by
1. hammering
2. heating
3. rough handling
4. all of these.
Answer: 4. all of these.
Each of these actions provides energy to the internal atoms, allowing them to shift and ruin their organized alignment. To keep a magnet strong, you must avoid all three of these conditions.
Teacher's Tip: To ruin a magnet: Burn it, Bash it, or Break it!
Exam Tip: "All of these" is a common correct choice for demagnetization questions.

B. Fill in the blanks.

1. A freely suspended magnet always comes to rest in the north- south direction.
Answer: north-south.
This consistency is used in all magnetic compasses throughout history. The Earth acts as a giant guide for every small magnet.
Teacher's Tip: North to North, South to South—the magnet never lies.
Exam Tip: This is known as the "Directive Property."

2. Permanent magnets are generally made of steel, cobalt, nickel, or an alloy called ALNICO.
Answer: ALNICO.
ALNICO is named after the three metals it is made of: Aluminum, Nickel, and Cobalt. This alloy is exceptional at resisting demagnetization.
Teacher's Tip: Al-Ni-Co is the ingredient list for permanent power.
Exam Tip: Memorize the name ALNICO as it's the standard alloy for strong magnets.

3. The perpendicular bisector of the line joining the two poles of a magnet is called magnetic equator.
Answer: magnetic equator.
Just like the Earth's equator is in the middle of its poles, the magnetic equator is the line exactly halfway between a magnet's ends. At this line, the attractive force is at its minimum.
Teacher's Tip: Equator = "Equal" distance from both poles.
Exam Tip: This is where iron filings will not stick to the magnet.

4. The north pole of the imaginary magnet of the earth is near the geographic south pole.
Answer: south.
This is a bit tricky! Since the "North" end of a magnet is attracted to it, the Earth's magnetic pole in the Arctic is actually a magnetic "South" pole.
Teacher's Tip: Remember: Magnetic South is near Geographic North!
Exam Tip: Don't get confused between "Geographic" and "Magnetic" poles.

5. Magnetic poles always exist in pairs.
Answer: pairs.
North and South are inseparable partners in the world of magnetism. This explains why every magnet, even if cut into tiny dust particles, still has two poles.
Teacher's Tip: Magnets are "Two-for-one" deals.
Exam Tip: Use "dipoles" as a technical term for extra credit.

C. State if the following statements are true or false. Correct the statement if it is false.

1. If a bar magnet is cut in two pieces, then one piece will have only the north pole and the other will have only the south pole.
Answer: False. If a bar magnet is cut in two pieces, then each of the piece will have the north pole and the south pole.
Breaking a magnet creates new surfaces where the internal field lines must enter and leave. This results in the immediate creation of two smaller, complete magnets.
Teacher's Tip: Magnetism is "Un-splittable" - you always get a N and an S.
Exam Tip: Draw the two new magnets to show you understand where the new poles form.

2. Attraction is the surest test for magnetism.
Answer: False. Repulsion is the surest test for magnetism.
Iron is attracted to magnets, but it is not a magnet itself. Only a second magnet can produce a pushing force (repulsion), proving that both objects have their own poles.
Teacher's Tip: Attraction = Iron. Repulsion = Magnet.
Exam Tip: This is a favorite "catch" question in exams; remember the Repulsion Rule.

3. Temporary magnets are made of cobalt.
Answer: False. Temporary magnets are made of soft iron.
Cobalt is actually used for permanent magnets because it helps retain a field. Soft iron is used for temporary ones because it lets magnetism "flow" through it only when needed.
Teacher's Tip: Soft iron is "Forgiving" - it lets go of magnetism easily.
Exam Tip: Associate "Soft Iron" with "Temporary" and "Steel/Alnico" with "Permanent."

4. As we move away from a magnet, its attraction power weakens.
Answer: True.
The magnetic field is strongest near the poles and dissipates as the distance increases. Once you are far enough away, the force becomes too weak to overcome the object's weight or friction.
Teacher's Tip: Magnets have a "Distance Limit" on their strength.
Exam Tip: This follows the "Inverse Square Law," meaning double the distance makes the force much weaker.

5. Whenever a magnet is not in use, it should be stored along with other magnets.
Answer: False. Whenever a magnet is not in use, it should not be stored along with other magnets.
Magnets stored randomly will push against each other and scramble their internal domain alignments. To store them correctly, use magnetic keepers and pair them up with opposite poles facing.
Teacher's Tip: Keep magnets "Quiet" and "Separated" (unless using keepers).
Exam Tip: Mention "Magnetic Keepers" as the correct way to store magnets.

D. Give reasons for the following.

Question 1: Magnets must be bandied with care.
Answer: Magnets must be handled with care or else they lose their magnetic properties and become weak. To prevent a magnet from becoming demagnetized, magnet should not be handled roughly, hammered, dropped, heated. It should be stored using magnetic keepers.
The internal arrangement of a magnet is very sensitive to physical and thermal energy. Proper storage and handling ensure that the magnet maintains its strength for its entire lifespan.
Teacher's Tip: Treat a magnet like a "Delicate Watch."
Exam Tip: List the "Three Enemies": Hammering, Dropping, and Heating.

Question 2: Iron is a magnetic substance.
Answer: Iron is a magnetic substance because it gets attracted by a magnet.
At the atomic level, iron atoms are like tiny compasses that can all swing to face the same direction when a magnet is near. This ability to align makes it "magnetic."
Teacher's Tip: Iron is the "Best Friend" of any magnet.
Exam Tip: Define a magnetic substance as any material attracted by a magnet.

Question 3: The directive property of magnets is used in a compass.
Answer: The directive property of magnet is used in a compass for navigation purposes as the magnetic needle inside the compass always rests in the geographical north-south direction.
Since the needle is extremely light and balanced, the weak pull of the Earth is enough to turn it. This provides a steady reference for direction regardless of the time of day or weather.
Teacher's Tip: Directive = "Points the way."
Exam Tip: Mention that the compass needle is a "small magnetized needle" for detail.

Question 4: Electromagnets are temporary magnets.
Answer: An electromagnet is a temporary magnet because it behaves like a magnet only till the current is passed through it. When the current is stopped, it stops behaving like a magnet.
The magnetism is entirely dependent on the flow of electrons through the coil. This ability to "switch off" makes electromagnets perfect for lifting heavy scrap metal and then dropping it by breaking the circuit.
Teacher's Tip: No Current = No Magnetism.
Exam Tip: Mention that the "soft iron core" is what allows it to lose magnetism quickly.

Question 5: Magnets are used to close the doors of a refrigerator tightly.
Answer: Because of the attractive property of a magnet. A magnet attracts magnetic substances by exerting a force called magnetic force. , This keeps the door of a refrigerator closed tightly.
A soft rubber gasket around the door contains magnetic strips that stick to the metal frame of the fridge. This creates an airtight seal that keeps the cold air inside and saves energy.
Teacher's Tip: Magnets act like "Invisible Latches" for fridge doors.
Exam Tip: Focus on the "Attractive Property" as the core reason.

E. Answer the following in short.

Question 1: Give two examples each of magnetic and. non-magnetic substances.
Answer: Examples of magnetic substances - Iron, nickel, cobalt. Examples of non-magnetic substances - Plastic, wool, wood, paper, rubber, etc.
Magnetic substances are mostly metals that can be influenced by a field. Non-magnetic substances include most of the common materials we use for clothing, building, and writing.
Teacher's Tip: Iron sticks; Wood skips!
Exam Tip: Always provide distinct examples from everyday life.

Question 2: What is a magnet ? Differentiate between natural and artificial magnets.
Answer: A magnet is a piece of metal that can attract metals such as iron cobalt and nickel. Naturally occurring rocks such as Lodestone or magnetite have the ability of attracting magnetic substances and hence are called natural magnets. Magnets that are made by man from magnetic substances ara called artificial magnets. These come in different shapes such as bar magnets, horse shoe magnets, disc magnets and ring magnets. Artificial magnets can be made in any size, shape or strength as desired but natural magnets cannot be made as desired.
Natural magnets were the starting point for human discovery, but artificial magnets are what power our world today. We can make artificial magnets hundreds of times stronger than anything found in a natural rock.
Teacher's Tip: Natural = Found; Artificial = Made.
Exam Tip: Use "strength" and "shape" as the main comparison points.

Question 3: If a bar magnet is placed over iron fillings, where will the attraction of the iron fillings be 1. maximum ? 2. minimum ?
Answer: 1. At the ends of the bar magnet. 2. At the centre of the magnet.
The magnetic force is concentrated at the poles (ends) because the field lines are crowded there. In the center (magnetic equator), the North and South influences essentially balance out, leaving very little net pull.
Teacher's Tip: The "Ends" are for "Effort," the "Middle" is "Mediocre."
Exam Tip: Identify the ends as the "poles" for a better technical answer.

Question 4: Define the following terms regarding a bar magnet, 1. Magnetic axis 2. Effective length 3. Magnetic equator 4. Magnetic field
Answer:
1. Magnetic axis: An imaginary line (XY) passing through the magnetic north pole and magnetic south pole of a bar magnet is called its magnetic axis.
2. Effective length: The distance (NS) between the north pole and south pole of a magnet is called the length or effective length of the magnet.
3. Magnetic equator: An imaginary line (PQ) bisecting the effective length of a magnet is called the magnetic equator of the magnet.
4. Magnetic field: The region around a magnet where its magnetic force can be experienced is called the magnetic field.
These geometric terms help scientists calculate the exact strength and behavior of a magnet. They define the "map" of the invisible forces surrounding the magnetized metal.
Teacher's Tip: Use these terms to describe the magnet's "Geography."
Exam Tip: In diagrams, the axis is the longitudinal line, and the equator is the vertical middle line.

Question 5: Name a few common appliances that use electromagnets.
Answer: Electric bells, electric motor, telephones, loudspeakers and generators are few common appliances that use electromagnets.
Electromagnets are vital because they can turn a magnetic field into mechanical motion or vibration. For example, in a speaker, the electromagnet vibrates to move air and create the sound you hear.
Teacher's Tip: Anything with a motor or a speaker likely has an electromagnet inside.
Exam Tip: List "Electric Bell" as the most common textbook example.

F. Answer the following in detail.

Question 1: Distinguish between a temporary magnet and a permanent magnet.
Answer:
Temporary magnet:
1. These magnets retain their magnetic property for a short duration of time.
2. These are made of soft iron.
3. They lose their magnetic properties once the magnetizing force is removed.
Permanent magnet:
1. These magnets retain their magnetic property always.
2. These are made of iron, steel, cobalt, nickel or an alloy called ANILCO.
3. They retain their magnetic properties even after the magnetizing force is removed.
The main difference is the "memory" of the material. Permanent magnets are like stone carvings that stay the same, while temporary magnets are like writing in water—gone as soon as you stop.
Teacher's Tip: Steel has "Magnetic Memory"; Soft Iron has "Amnesia."
Exam Tip: Always provide a table with three distinct points for a 3-mark question.

Question 2: Write a short note on the theory of magnetism.
Answer: All substances are made of minute particles. In a magnetic substance whether magnetized or non-magnetized), each individual particle behaves like an independent magnet. In the unmagnetized state, these particles within the substance are present in a random fashion such that they cancel out the magnetic effects of each other. In a magnetized state, these particles align in a particle direction and the substance behaves like a magnet.
Think of the particles as tiny compass needles. When they are all messy and pointing everywhere, they push and pull against each other; but when they all line up together, their power combines into one strong force.
Teacher's Tip: Magnetism is "Teamwork" at the atomic level.
Exam Tip: Use the term "molecular magnets" to describe the tiny particles.

Question 3: List four methods of magnetizing a magnetic substance.
Answer: Methods of magnetizing a magnetic material are :
1. Single-touch method - A magnet is rubbed along the magnetic substance from one end to another.
2. Double-touch method - Opposite poles of two magnets are placed next to each other at the centre of the magnetic substance and rubbed in opposite direction along it.
3. Magnetizing by induction - It is a method to make temporary magnets under the influence of a magnetizing force. The magnetic properties disappear when the influence of the magnetizing force is removed. (A permanent magnet is brought close to the magnetic substance but not touched.)
4. Electric current - A magnet made by using electric current is called an electromagnet. It is a temporary magnet and stops behaving like a magnet when the current is stopped. Electromagnets can become permanent magnets if certain materials like steel and special alloys are placed in a coil and very strong current is passed through the coil.
These methods cover both manual ways to align atoms and advanced electrical techniques. Each method has its own use depending on whether you need a quick temporary tool or a long-lasting magnet.
Teacher's Tip: Remember the "Big Four": Single Touch, Double Touch, Induction, and Current.
Exam Tip: If asked to describe them, always mention if the resulting magnet is "temporary" or "permanent."

Question 4: How is the single-touch method of magnetism different from the double-touch method ?
Answer: (i) A magnet is rubbed along the magnetic substance (needle or iron piece) from one end to another and lifted vertically upwards. (ii) Opposite poles of two magnets are placed next to each other at the centre of the magnetic substance and rubbed in opposite direction.
The single-touch method uses one magnet to slowly align particles from start to finish. The double-touch method is more efficient because it uses two magnets to align both halves of the bar at the same time, usually creating a stronger magnet.
Teacher's Tip: Single = 1 Magnet; Double = 2 Magnets from the center.
Exam Tip: Use diagrams to show the movement of the magnets for both methods.

Question 5: How can a magnet be demagnetized ?
Answer: A magnet can be demagnetized in the following ways :
1. rough handling
2. hammering the magnet several times.
3. passing an alternating current around the magnet.
4. dropping the magnet on the floor several times.
5. heating the magnet to a very high temperature.
These methods disrupt the uniform alignment of the molecular magnets. When they lose their order and point in different directions again, the overall magnetic pull of the object is lost.
Teacher's Tip: Rough and Hot is the end of the magnet.
Exam Tip: Mentioning "Alternating Current (AC)" is a sophisticated point that will impress your teacher.