Magnetism — Complete Exercise Solutions
Use this page alongside the official Samacheer Kalvi 6th Science Term 3, Chapter 1: Magnetism textbook. Solve each exercise on your own first, then check your answers below.
I. Choose the Appropriate Answer (MCQ)
Q1. An object that is attracted by a magnet
- (a) wooden piece
- (b) plain pins ✓
- (c) eraser
- (d) piece of paper
Pins are made of steel (iron-based), which is a magnetic material. Wood, rubber (eraser), and paper are non-magnetic materials — they are not attracted by a magnet.
Q2. People who made mariner's compass for the first time
- (a) Indians
- (b) Europeans
- (c) Chinese ✓
- (d) Egyptians
The Chinese invented the mariner's compass during the Han Dynasty (around 200 BC). They observed that lodestone (a naturally magnetic ore) always aligned itself in the north-south direction and used this property for navigation.
Q3. A freely suspended magnet always comes to rest in the ________ direction
- (a) North-East
- (b) South-West
- (c) East-West
- (d) North-South ✓
A freely suspended magnet aligns itself along the Earth's magnetic field. One end points toward geographic north (the north pole of the magnet) and the other toward geographic south (the south pole of the magnet).
Q4. Magnets lose their properties when they are
- (a) used
- (b) stored
- (c) hit with a hammer ✓
- (d) cleaned
Hammering, heating, or dropping a magnet from a height causes the magnetic domains inside the material to become disordered, which destroys the magnet's magnetic property.
Q5. Mariner's compass is used to find
- (a) speed
- (b) displacement
- (c) direction ✓
- (d) motion
A mariner's compass contains a magnetic needle that rotates freely and always comes to rest pointing north-south. Sailors and travellers use it to determine direction.
Additional MCQ — Iron objects are attracted by magnets
- (a) Plastic
- (b) Iron ✓
- (c) Glass
- (d) Wax
Iron is a magnetic material. Plastic, glass, and wax are non-magnetic.
Additional MCQ — Magnets lose their property if they are
- (a) heated
- (b) dropped
- (c) hit with a hammer
- (d) all of these ✓
All three actions — heating, dropping, and hammering — disorder the magnetic domains and cause a magnet to lose its magnetic properties.
Additional MCQ — ________ poles repel each other
- (i) N–N
- (ii) N–S
- (iii) S–N
- (iv) S–S
- (a) i and ii
- (b) ii and iii
- (c) iii and iv
- (d) i and iv ✓
Like poles (both north or both south) repel each other. Unlike poles (N–S or S–N) attract each other.
Additional MCQ — When the N pole of a magnet approaches the N pole of another magnet, they
- (a) attract
- (b) repel ✓
- (c) rotate
- (d) none of these
Like poles (N–N or S–S) always repel each other.
Additional MCQ — Electromagnetic train speed
- (a) 1200
- (b) 600 ✓
- (c) 100
- (d) 800
Electromagnetic (maglev) trains use magnetic levitation and can reach speeds up to 600 km/hr.
II. Fill in the Blanks
1. Artificial magnets are made in different shapes such as ________
Artificial magnets are man-made and come in various shapes for different uses — bar magnets for general experiments, horseshoe magnets for lifting heavy objects, and ring magnets for speakers and scientific instruments.
2. The materials which are attracted towards the magnet are called ________
Magnetic materials include iron, nickel, cobalt, and steel. These are attracted by magnets because their atoms can align their magnetic domains in the presence of a magnetic field.
3. Paper is not a ________ material.
Paper is a non-magnetic material. It is not attracted by a magnet and cannot be magnetised.
4. In olden days, sailors used to find direction by suspending a piece of ________
Lodestone is a naturally occurring magnetic ore (magnetite). Ancient sailors suspended a piece of lodestone on a string; it would always come to rest pointing north-south, helping them navigate.
5. A magnet always has ________ poles.
Every magnet, regardless of its shape or size, always has two poles — a north pole and a south pole. Even if a magnet is cut into pieces, each piece will have both poles.
Additional Fill in the Blanks
6. The magnetic ore is called ________
Magnetite (Fe₃O₄) is a naturally occurring magnetic ore. It is also known as lodestone.
7. ________ magnets do not have a definite shape.
Natural magnets (lodestones) are found in nature and have irregular, undefined shapes. Artificial magnets are man-made and can be shaped as desired.
8. Man-made magnets are called ________ magnets.
Artificial magnets are manufactured by magnetising pieces of iron or steel. They come in specific shapes such as bar, horseshoe, and ring magnets.
9. A ________ is used to find directions.
A magnetic compass has a lightweight magnetic needle that rotates freely and always aligns in the north-south direction.
10. ________ will also get affected by a magnetic field.
Cell phones contain components (speakers, vibration motors) that use magnets. Strong external magnetic fields can interfere with their functioning.
11. For a horse-shoe magnet, a single piece of soft iron is used as a ________
A keeper (also called an armature) is a piece of soft iron placed across the poles of a horseshoe magnet during storage. It completes the magnetic circuit and prevents the magnet from losing its strength.
III. True or False (with corrections)
Q1. A cylindrical magnet has only one pole.
Correction: A cylindrical magnet has two poles. No magnet — regardless of its shape (bar, cylindrical, ring, or horseshoe) — can have only one pole. If you cut a cylindrical magnet, each piece will still have both a north pole and a south pole.
Q2. Similar poles of a magnet repel each other.
Like poles (N–N or S–S) repel each other. This is a fundamental property of magnets. The repulsive force pushes the magnets apart.
Q3. Maximum iron filings stick in the middle of a bar magnet.
Correction: Maximum iron filings stick at the poles (ends) of a bar magnet, not in the middle. The magnetic force is strongest at the poles and weakest at the centre.
Q4. A compass can be used to find East-West direction at any place.
A compass needle always points in the north-south direction. East and West are perpendicular to the north-south line, so once you know north-south, you can easily determine east-west.
Q5. Rubber is a magnetic material.
Correction: Rubber is a non-magnetic material. It is not attracted by a magnet and cannot be magnetised. Magnetic materials include iron, nickel, cobalt, and steel.
IV. Match the Following
| Column I | Column II |
|---|---|
| Compass | Magnetic needle |
| Attraction | Opposite poles |
| Repulsion | Like poles |
| Magnetic poles | Maximum magnetic strength |
- Compass contains a magnetic needle that rotates freely and points north-south.
- Attraction occurs between opposite poles (unlike poles — N and S attract each other).
- Repulsion occurs between like poles (N–N or S–S repel each other).
- Magnetic poles are the regions of maximum magnetic strength on a magnet.
V. Circle the Odd Ones
Q1. Iron nail, Pins, Rubber tube, Needle
Iron nail, pins, and needle are all made of iron/steel — they are magnetic materials. A rubber tube is a non-magnetic material and is not attracted by a magnet.
Q2. Lift, Escalator, Electromagnetic train, Electric bulb
Lifts, escalators, and electromagnetic trains all use electromagnets in their working mechanism. An electric bulb works on the heating effect of electric current and does not use electromagnets.
Q3. Attraction, Repulsion, Pointing direction, Illumination
Attraction, repulsion, and pointing direction (towards north-south) are all properties of magnets. Illumination is not a magnetic property — it relates to light, not magnetism.
VI. Magnet Diagrams — Attract, Repel, or Turn Around
The textbook presents diagrams of two bar magnets placed near each other. For each arrangement, predict whether the magnets attract, repel, or turn around.
| Scenario | Poles Facing | Result | Reason |
|---|---|---|---|
| (a) S–N poles facing | Unlike poles | Attract | Opposite poles attract each other |
| (b) S–S poles facing | Like poles | Repel | Same poles repel each other |
| (c) N–S poles facing | Unlike poles | Attract | Opposite poles attract each other |
| (d) Perpendicular orientation | Poles not aligned | Turn around | Magnet rotates to align N–S |
| (e) N–N poles facing | Like poles | Repel | Same poles repel each other |
| (f) Perpendicular orientation | Poles not aligned | Turn around | Magnet rotates to align N–S |
Key principle: Unlike poles (N–S) attract, like poles (N–N, S–S) repel. A freely suspended magnet always rotates to align itself in the north-south direction.
VII. Very Short Answers
Q1. What are the two poles of a magnet called?
Q2. Name any three magnetic materials.
Q3. Name any three non-magnetic materials.
Q4. What is a lodestone?
Q5. What is the use of a magnetic compass?
VIII. Short Answers
Q1. Explain attraction and repulsion between magnetic poles.
- Attraction: Unlike poles (North and South) of two magnets attract each other. If you bring the north pole of one magnet near the south pole of another, they pull toward each other.
- Repulsion: Like poles (North–North or South–South) of two magnets repel each other. If you bring two north poles or two south poles near each other, they push away from each other.
This is the fundamental rule of magnetism: Like poles repel; unlike poles attract.
Q2. List three ways magnets lose their magnetic force.
1. Heating: If a magnet is heated to a high temperature, its magnetic domains become disordered, and it loses its magnetism. 2. Dropping from a height: When a magnet falls and hits the ground, the impact disorder its magnetic domains. 3. Hammering: Striking a magnet with a hammer disrupts the alignment of its magnetic domains, weakening or destroying its magnetic property.
Other causes include storing magnets improperly (without keepers) and placing them near strong electrical currents.
Q3. Differentiate between natural and artificial magnets.
| Property | Natural Magnets | Artificial Magnets |
|---|---|---|
| Origin | Found in nature (lodestone) | Man-made by magnetising iron/steel |
| Shape | Irregular, no definite shape | Specific shapes — bar, horseshoe, ring |
| Magnetic strength | Weak | Strong |
| Duration of magnetism | Permanent but weak | Can be permanent (steel) or temporary (soft iron) |
| Examples | Lodestone (magnetite) | Bar magnet, horseshoe magnet, ring magnet |
Q4. Why should magnets be stored with keepers?
1. Complete the magnetic circuit, preventing the magnetic field lines from spreading out. 2. Prevent the magnet from losing its strength over time. 3. Protect the magnet from external magnetic fields that could weaken it. 4. Prevent accidental attraction of nearby iron objects.
IX. Detailed Answers
Q1. How do you magnetise an iron needle? Describe the method step by step.
An iron needle can be magnetised using the single-touch method (also called the stroking method):
1. Place the iron needle flat on a table or a smooth surface. 2. Take a bar magnet and place one of its poles near one end of the needle. 3. Stroke the magnet from one end of the needle to the other end in one direction only — do not rub back and forth. 4. Lift the magnet away from the needle after reaching the far end and bring it back to the starting end. 5. Repeat the stroking process 30–40 times in the same direction. 6. Test the needle by bringing a pin or some iron filings near it. If the pin is attracted, the needle has been magnetised.
Important precautions:
- Always stroke in the same direction — never change the direction.
- Do not slide the magnet back and forth — this can cancel the magnetisation.
- The pole of the magnet at the starting end becomes the opposite pole of the needle. For example, if you use the north pole of the magnet to stroke, the end where you begin becomes the south pole of the needle.
Q2. How does an electromagnetic train (maglev train) work?
An electromagnetic train (magnetic levitation or maglev train) works on the principle of magnetic repulsion and attraction:
1. Electromagnets are fitted at the bottom of the train and on the rail tracks. 2. Like poles repel: The electromagnets on the train and track are arranged so that like poles face each other. This repulsion lifts (levitates) the train about 10 cm above the track. 3. No friction: Since the train floats above the track, there is no contact and therefore no friction between the train and the rails. 4. Propulsion: By controlling the direction of electric current in the track electromagnets, the poles can be changed. The electromagnets ahead of the train attract it forward, while those behind repel it — pushing the train ahead. 5. Speed: Without friction, maglev trains can reach speeds of up to 600 km/hr, much faster than conventional trains.
Advantages of maglev trains:
- No friction, so less energy wasted
- Very high speed
- Smooth and silent ride
- Less wear and tear since there is no physical contact
Q3. Describe the properties of magnets.
The key properties of magnets are:
1. Attractive property: A magnet attracts magnetic materials like iron, nickel, cobalt, and steel. The force of attraction is strongest at the poles.
2. Directive property: A freely suspended magnet always comes to rest in the north-south direction. The end pointing north is the north pole; the end pointing south is the south pole.
3. Two poles: Every magnet has two poles — a north pole and a south pole. Even if a magnet is cut into pieces, each piece will have both poles. A single isolated pole (monopole) does not exist.
4. Like poles repel, unlike poles attract: Two north poles or two south poles push away from each other. A north pole and a south pole pull toward each other.
5. Magnetic strength is strongest at the poles: When iron filings are sprinkled on a magnet, most filings cluster at the poles, not in the middle.
6. Magnetic induction: A magnet can induce magnetism in a nearby magnetic material without direct contact. For example, an iron nail placed near a magnet becomes temporarily magnetised.
7. Magnetism can be destroyed: Heating, hammering, or dropping a magnet can cause it to lose its magnetic properties.
Q4. Write a note on the magnetic compass and its uses.
Magnetic compass:
A magnetic compass is a navigational instrument that uses a lightweight magnetic needle mounted on a pivot. The needle can rotate freely and always comes to rest pointing in the north-south direction.
How it works:
- The compass needle is a small bar magnet.
- The Earth itself acts like a giant magnet, with its magnetic south pole near the geographic north pole and its magnetic north pole near the geographic south pole.
- The north pole of the compass needle is attracted toward the Earth's magnetic south (near geographic north), so it points north.
Uses of the magnetic compass:
1. Navigation on sea: Sailors use compasses to determine direction and plot their course across oceans. 2. Navigation on land: Travellers and hikers use compasses to find their way in forests, mountains, and deserts. 3. Military: Armed forces use compasses for orientation and map reading. 4. Surveying: Surveyors use compasses to determine directions when mapping land. 5. Aircraft navigation: Pilots use compasses as a backup navigational tool.
History: The Chinese first invented the mariner's compass using lodestone. It revolutionised sea travel and made long ocean voyages possible.
Common Mistakes
1. Saying like poles attract each other. Remember: Like poles repel, unlike poles attract. N–N repels, S–S repels, N–S attracts. Use the simple rule — "same push, opposite pull."
2. Saying maximum iron filings stick at the centre of a magnet. The magnetic force is strongest at the poles (ends), not at the centre. When iron filings are sprinkled, they cluster at the two ends. The centre has almost no magnetic strength.
3. Confusing magnetic and non-magnetic materials. Magnetic materials are attracted by magnets — iron, steel, nickel, cobalt. Non-magnetic materials are not attracted — wood, plastic, rubber, glass, paper, cloth. Note: not all metals are magnetic (aluminium, copper, gold are non-magnetic metals).
4. Thinking a magnet can have only one pole. Every magnet, no matter how small or what shape, always has two poles. Even if you break a magnet in half, each piece develops both a north and south pole. Magnetic monopoles do not exist.
5. Confusing natural and artificial magnets. Natural magnets (lodestone) are found in nature, have irregular shapes, and are weak. Artificial magnets are man-made, come in specific shapes (bar, horseshoe, ring), and are much stronger.
6. Forgetting that magnets can lose their properties. Magnets lose magnetism if they are heated, hammered, or dropped from a height. Always handle magnets carefully and store them with keepers.
7. Saying the compass needle points to geographic north. The compass needle points to the magnetic north, which is close to but not exactly the same as geographic north. This slight difference is called magnetic declination. For Class 6, it is acceptable to say the compass points "in the north-south direction."
Exam Checklist
- [ ] Identify magnetic and non-magnetic materials with examples
- [ ] State the two poles of a magnet and their properties
- [ ] Explain the rule: like poles repel, unlike poles attract
- [ ] Describe the directive property of a freely suspended magnet
- [ ] Differentiate between natural and artificial magnets
- [ ] List the shapes of artificial magnets (bar, horseshoe, ring)
- [ ] Describe the single-touch method of magnetising an iron needle
- [ ] Explain three ways a magnet can lose its properties (heat, hammer, drop)
- [ ] Explain why iron filings cluster at the poles and not the centre
- [ ] Describe the magnetic compass and its uses
- [ ] Explain how an electromagnetic (maglev) train works
- [ ] State why magnets are stored with keepers
- [ ] Identify odd-one-out questions based on magnetic vs. non-magnetic properties
- [ ] Correctly answer True/False questions about magnetism properties