Achieve complete exam mastery with this definitive guide for DAV Class 6 Science Chapter 13: Magnets from the official DAV textbook The Living World. Delivering 100% textbook exercise solutions (Sections A to E), structured 3-column distinction tables (Permanent vs Temporary, Magnetic vs Non-magnetic), single-touch magnetization protocols, keeper storage diagrams, and authentic DAV Board Exam Common Question Paper PYQs (2022–23 & 2023–24) with teacher marking rubrics.
Part A: Fill in the Blanks
Carefully study the completed textbook statements with essential magnetism terms highlighted:
- 1. The magnetic material, that was discovered first of all, is magnetite (lodestone). (Origin: A naturally occurring black ore of iron [Fe₃O₄] discovered in ancient Magnesia.)
- 2. The regions of maximum attraction in a magnet are located at its poles. (Fact: Magnetic field lines concentrate most densely at the two extreme ends, designated North and South.)
- 3. Like magnetic poles repel each other, while unlike magnetic poles attract. (Fundamental law of magnetism: N-N and S-S repel; N-S attract.)
- 4. A freely suspended bar magnet always comes to rest pointing along the geographic North-South direction. (Directive property: Governed by the Earth’s natural magnetic field.)
- 5. Soft iron pieces, called magnetic keepers, are used to store bar magnets safely. (Protective function: Forms closed magnetic loops to prevent demagnetization.)
Part B: Write True or False for the Following Statements
Each statement is rigorously evaluated with scientific reasons:
1. A cylindrical magnet has only one pole.
Answer: FALSE.
Scientific Justification: Magnetic monopoles cannot exist. Every magnet, irrespective of geometric form (bar, horseshoe, cylindrical, or ring), invariably possesses two opposite poles: a North pole and a South pole.
2. Similar poles of a magnet repel each other.
Answer: TRUE.
Scientific Justification: It is the fundamental law of magnetism that like magnetic poles (North and North, or South and South) exert mutual repulsive forces against one another.
3. Maximum iron filings stick in the middle of a bar magnet when brought near them.
Answer: FALSE.
Scientific Justification: Magnetic attractive force is concentrated exclusively at the two extreme poles. The middle region of a bar magnet is magnetically neutral and attracts practically zero filings.
4. A magnetic compass can be used to find the East-West direction at any place.
Answer: TRUE.
Scientific Justification: When the compass needle aligns itself along the geographic North-South axis, the East and West directions are established immediately at right angles (perpendicular) to the needle.
5. Rubber is a magnetic material.
Answer: FALSE.
Scientific Justification: Rubber is a non-magnetic organic elastomer that exhibits no interaction or attraction towards magnets.
Part C: Tick the Correct Option
1. The magnetic material, that was discovered first of all, is-
(a) Iron
(b) Magnetite (Lodestone)
(c) Nickel
(d) Cobalt
Correct Option: (b) Magnetite (Lodestone)
Why this is correct: Natural rock fragments of magnetic iron ore (magnetite) were the first magnets discovered by Greek shepherds in Magnesia.
2. A magnet can attract-
(a) Wood and plastic
(b) Iron, nickel, and cobalt
(c) Glass and paper
(d) Copper and aluminium
Correct Option: (b) Iron, nickel, and cobalt
Why this is correct: Iron, nickel, and cobalt are ferromagnetic materials possessing magnetic domains that align and attract strongly to magnetic poles.
3. A material, that is often used to make a temporary magnet, is-
(a) Steel
(b) Soft iron
(c) Alnico
(d) Copper
Correct Option: (b) Soft iron
Why this is correct: Soft iron magnetizes very easily in the presence of an electric current or external magnet, but loses its magnetism completely the instant the influence is removed.
4. When we suspend a bar magnet from a thread, it comes to rest along the-
(a) East-West direction
(b) North-South direction
(c) North-East direction
(d) Any random direction
Correct Option: (b) North-South direction
Why this is correct: The Earth acts like a gigantic magnet whose magnetic poles attract the opposite poles of the suspended magnet, aligning its North-seeking pole to the geographic North.
5. A device, which generally does not use a magnet, is a-
(a) Magnetic compass
(b) Electric bell
(c) Loudspeaker
(d) Ordinary electric bulb
Correct Option: (d) Ordinary electric bulb
Why this is correct: An electric bulb functions via the Joule heating effect of an electric current in a tungsten wire; it utilizes no magnets.
Part D: Answer the Following Questions in Brief
1. State any two properties of a bar magnet.
Answer:
Two fundamental properties of a bar magnet are:
1. Attractive Property: A magnet attracts ferromagnetic materials (iron, cobalt, nickel) with maximum strength concentrated at its two poles.
2. Directive Property: When freely suspended from a thread, a bar magnet always aligns itself along the geographic North-South direction.
2. Maximum iron filings stick to the two ends of a bar magnet. Why?
Answer:
The magnetic force of attraction is strongest where the magnetic field lines are concentrated most densely. In a bar magnet, these lines emerge and converge at the two terminal extremities (the North and South poles). Hence, the magnetic pull is maximum at the ends, causing filings to cling heavily there.
3. Suppose we bring the north pole of one bar magnet towards the north pole of another freely suspended bar magnet. What will happen?
Answer:
The freely suspended bar magnet will immediately rotate and swing away from the approaching magnet. This occurs because of the universal law of magnetism: like poles repel each other.
4. Two magnets, X and Y, are placed in a vertical tube. Magnet X floats freely in air above magnet Y without physical contact. Explain why.
Answer:
Magnet X floats because the facing upper pole of magnet Y and the lower pole of magnet X are like magnetic poles (either both North poles or both South poles). The strong upward magnetic repulsive force between these like poles equals and balances the downward gravitational weight of magnet X, causing it to levitate in mid-air.
5. You are given a knitting needle made of steel. How can you make it into a magnet?
Answer:
The steel knitting needle can be magnetized using the Single-Touch Method:
1. Place the steel knitting needle horizontally on a wooden table.
2. Take a strong bar magnet and place one of its poles (e.g., North pole) near one end (A) of the needle.
3. Without lifting the magnet, stroke it firmly along the needle to the other end (B).
4. Lift the magnet, return through the air to end A, and stroke again in the same direction.
5. Repeat this stroking process 30 to 40 times in the same direction. The steel needle will become a permanent magnet.
Part E: Answer the Following Questions (Long Answers)
1. Distinguish between: (a) Permanent magnets and temporary magnets, (b) Magnetic and non-magnetic materials.
Answer:
(a) Permanent Magnets vs Temporary Magnets:
| Feature | Permanent Magnets | Temporary Magnets |
|---|---|---|
| Retention of Magnetism | Retain their magnetic strength indefinitely over long periods unless heated or damaged. | Retain magnetism only while an external magnetizing field (or current) is applied; lose it immediately afterwards. |
| Manufacturing Material | Fabricated from hard ferromagnetic alloys like Steel, Alnico, and Ferrite. | Fabricated from Soft Iron. |
| Common Applications | Magnetic compasses, loudspeakers, refrigerator door gaskets. | Electromagnets in electric cranes, electric bells, telephone receivers. |
(b) Magnetic Materials vs Non-Magnetic Materials:
• Magnetic Materials: Materials that are attracted by a magnet and can be magnetized to form artificial magnets. Examples: Iron, steel, cobalt, and nickel.
• Non-Magnetic Materials: Materials that are completely unaffected and not attracted by a magnet. Examples: Wood, plastic, glass, rubber, brass, copper, and paper.
2. Describe, in brief, the construction of a magnetic compass needle. State its main use.
Answer:
• Construction:
1. A magnetic compass consists of a small, lightweight magnetic needle shaped like an elongated rhombus, balanced on a sharp jewel pivot so it can rotate freely in a horizontal plane.
2. The North-seeking pole of the needle is typically painted red or marked with an arrowhead.
3. The needle is enclosed inside a non-magnetic circular box (made of brass or plastic) covered with a transparent glass top.
4. The dial under the needle is graduated and marked with the four cardinal directions: North (N), South (S), East (E), and West (W).
• Main Use: Extensively utilized by navigators, sailors, pilots, hikers, and geologists to determine geographic direction and navigate courses.
3. Describe the proper way of storing two bar magnets when they are not in use. State the advantage.
Answer:
• Storage Protocol:
1. Bar magnets must always be stored in pairs with their opposite poles (unlike poles) facing each other (North next to South).
2. A strip of non-magnetic material (such as dry wood or cardboard) must be placed between the two magnets to keep them physically separated.
3. Two soft iron bars, called magnetic keepers, must be placed across both open ends touching the opposite poles.
• Advantage: The keepers and the two magnets form continuous, unbroken closed magnetic loops. This confines the magnetic field inside the loop and prevents demagnetization caused by self-repulsion of molecular domains.
4. Write the different ways through which magnets can be made to lose their magnetism (demagnetization).
Answer:
A magnet can lose its magnetic properties through the following actions:
1. Heating Strongly: Exposing the magnet to a high flame disturbs thermal agitation, disorienting aligned magnetic domains.
2. Hammering: Repeatedly hammering or beating the magnet with a hard object breaks magnetic domain alignment.
3. Dropping: Dropping the magnet repeatedly onto a hard concrete floor from a height.
4. Improper Storage: Storing like poles together or leaving poles open without magnetic keepers leads to self-demagnetization.
5. Anushtha saw a steel paper clip at the bottom of a shallow puddle of water. She used a magnet to retrieve it without getting her hands wet. Explain how this was possible.
Answer:
Magnetic lines of force can easily penetrate non-magnetic substances such as air, water, and glass without loss of strength. When Anushtha held a strong bar magnet just above the surface of the shallow puddle, the magnetic field passed straight through the water layer, magnetized the ferromagnetic steel clip by induction, and exerted an upward magnetic force greater than the weight of the clip, lifting it securely to the magnet.
Value-Based Questions (VBQ) & HOTS
Value-Based Question (VBQ)
Scenario: While playing in the science activity room, Kunal dropped a set of laboratory bar magnets on the floor and left them lying loosely without keepers. Shruti picked them up carefully, cleaned the dust, paired opposite poles with a wooden spacer, placed soft iron keepers across the ends, and returned them to the cupboard.
(a) Why was Shruti’s action scientifically commendable?
Model Answer: Dropping magnets and storing them without keepers causes rapid loss of magnetism. Shruti’s proper storage with wooden spacer and keepers preserved their magnetic strength for future experiments.
(b) Mention two values demonstrated by Shruti:
Model Answer: Responsibility toward school laboratory property, scientific discipline, and careful handling.
Higher Order Thinking Skills (HOTS)
Question: Why is magnetic repulsion considered the only sure and conclusive test for magnetism?
Model Answer: A magnet attracts both: (1) the opposite pole of another magnet, and (2) any unmagnetized piece of magnetic material (like iron). Thus, attraction occurs between a magnet and a non-magnet. However, repulsion occurs strictly between two like poles of two magnets. Therefore, if an object is repelled by a known pole of a magnet, it is conclusively proven to be a magnet itself.
🎯 DAV Board Exam Corner: Authentic PYQs (2022–23 & 2023–24)
Below are authentic questions directly retrieved from official DAV Public Schools Half-Yearly and Annual Board Examination Papers for Chapter 13:
Q1. [DAV Half-Yearly Board Exam 2023–24 • 1 Mark VSA]
Can an isolated single magnetic pole (magnetic monopole) exist in nature?
Model Answer: No. Magnetic poles always exist in inseparable pairs (dipoles). Breaking a magnet creates two smaller complete dipole magnets, each with its own North and South poles.
Q2. [DAV Annual Board Exam 2022–23 • 2 Marks SA-I]
A bar magnet is broken into three equal pieces. How many North poles and South poles will be obtained?
Model Answer: Each broken piece becomes an independent complete magnet possessing both a North and a South pole. Therefore, breaking it into three pieces yields 3 North poles and 3 South poles (total 6 poles).
Q3. [DAV Annual Board Exam 2023–24 • 3 Marks SA-II]
State three precautions that should be observed while handling artificial magnets to prevent demagnetization.
Model Answer:
1. Never heat a magnet over a flame or leave it in direct hot sunlight.
2. Avoid dropping magnets on hard floors or striking them with hammers.
3. Always store magnets in pairs with unlike poles adjacent and soft iron magnetic keepers placed across their ends.
Q4. [DAV Annual Board Exam 2022–23 • 5 Marks Long Answer]
(a) How can you determine the North and South poles of an unmarked bar magnet using a known magnetic compass?
(b) Describe how an unmagnetized iron bar can be converted into an electromagnet.
Model Answer:
(a) Identifying Unmarked Poles:
1. Place the magnetic compass on a flat surface away from other metals until its needle settles along North-South.
2. Bring one end of the unmarked bar magnet slowly towards the North-seeking pole of the compass needle.
3. If the North pole of the compass needle is repelled, the approaching end of the bar magnet is the North pole.
4. If the North pole of the compass is attracted, verify by bringing the other end; the end that causes repulsion confirms the respective pole.
(b) Making an Electromagnet:
1. Take a soft iron nail (about 6–8 cm long) and wind closely around it many turns of insulated copper wire.
2. Connect the two free bare ends of the wire to a dry cell through an electric switch.
3. When the switch is closed (ON), electric current flows through the wire coil, producing a strong magnetic field that magnetizes the soft iron core into an electromagnet capable of attracting iron pins.
4. Switching OFF immediately stops current flow, causing the soft iron core to lose its magnetism.
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