TOPIC 13 OF 46

Compass, Applications and Demagnetising

🎓 Class 6 Science CBSE Theory Ch 4 — Exploring Magnets ⏱ ~14 min
🌐 Language: [gtranslate]

This MCQ module is based on: Compass, Applications and Demagnetising

[myaischool_lt_science_assessment grade_level="class_6" science_domain="physics" difficulty="basic"]

4.6 Using a Magnetic Compass

The needle of a compass is nothing but a tiny, thin bar magnet. Because Earth itself is a huge magnet, this needle always turns and settles along the North–South line. The red (or painted) tip of the needle points towards the geographic North. The other (white or black) end points to the South.

A very old invention: Chinese navigators were already using a floating compass made of lodestone by the 11th century. This single device let sailors travel across open oceans without stars or landmarks.

Activity 4.8 — Aligning Your Compass L3 Apply
  1. Keep your compass flat on a table far away from iron objects, mobile phones, speakers and laptop magnets.
  2. Wait till the needle comes to rest.
  3. Gently rotate the body of the compass (not the needle) so that the mark 'N' on the dial sits exactly under the red end of the needle.
  4. Now the dial tells you the true directions: E is to your right if you face N, W to your left, S behind you.
Because Earth's magnet always pulls the red end of the needle towards geographic North, the compass is a free, battery-free direction finder that works anywhere on Earth!
N S E W NE NW SE SW
Fig 4.10 — A compass dial showing the eight main directions

4.7 Magnets in Our Daily Life

You might think magnets are rare lab items — but in fact, they are everywhere around you!

At Home

🚪
Fridge Door
A thin rubber strip containing a ferrite magnet seals the fridge door tightly so cold air doesn't escape.
👝
Purse & Pencil Box Clasps
Tiny button magnets snap bags and boxes shut.
🎨
Fridge Magnets
Decorative magnets that hold paper notes on the steel door.
💳
Credit/Debit Cards
The black stripe on the back is a magnetic strip that stores your account data.

In Industry

🏗️
Giant Cranes
Electromagnets on cranes pick up tonnes of iron scrap at junkyards and ports.
♻️
Recycling
Magnets separate iron from mixed waste so it can be melted and reused.
🔊
Loudspeakers & Earphones
A coil and magnet work together to make sound vibrations.
⚙️
Electric Motors
Fans, washing machines, mixers — every electric motor has magnets inside.
💽
Hard Disks
Data on a computer's hard disk is stored as tiny magnetised spots.

In Medicine & Travel

🏥
MRI Scans
Magnetic Resonance Imaging uses a very strong magnet to make clear pictures of the inside of your body, with no X-rays!
✈️
Navigation
Pilots, ship captains, hikers and scouts carry compasses to find direction anywhere.
Crane electromagnet lifts iron scrap coil Loudspeaker magnet + coil = sound MRI MACHINE MRI scan strong magnet images body
Fig 4.11 — Three everyday uses of magnets: crane, loudspeaker and MRI scanner

4.8 Caring for Magnets

A magnet is strong but also delicate! If not handled properly, it loses its magnetism — we say it becomes demagnetised.

How Magnets Lose Their Strength

🔥
Heating
Placing a magnet in fire or near a stove disturbs its inner alignment.
🔨
Hammering
Rough hammering shakes the particles out of line.
⬇️
Dropping
Sudden hard drops, again and again, reduce magnetic power.
Wrong Storage
Storing magnets far apart, or with like poles facing, weakens them.

Right Way to Store Magnets

Store two bar magnets side by side with opposite poles (N facing S) touching, and place small soft-iron pieces (called keepers) across their ends. This keeps the magnetism locked inside.

✓ Correct Storage NS SN Iron keeper Iron keeper Opposite poles together + soft iron bars at ends
Fig 4.12 — Storing bar magnets with iron keepers keeps them strong for years
Keep magnets away from:
  • Television screens and computer monitors — magnets can distort the picture.
  • Credit/debit cards — the magnetic strip can get erased.
  • Wristwatches — the tiny metal parts inside can get magnetised and stop keeping time.
  • Mobile phones and pacemakers — sensitive electronics may be disturbed.

Interactive: Find the Direction! L3

The red end of the compass needle points North. Use the picture below and click the correct direction for each riddle.

N S E W
If you face North, which direction is to your right?
Score: 0 / 0

Competency-Based Questions

Reshma's father is a ship navigator. He tells her that even with GPS available, every ship must carry a magnetic compass as a backup. He also shows her how to store their box of bar magnets properly.

Q1. A compass needle always settles in the: L1

  • A. East-West direction
  • B. Up-Down direction
  • C. North-South direction
  • D. Random direction
Answer: C. Earth's magnetism always pulls the compass needle to the North-South line.

Q2. Which of these is NOT a good way to store bar magnets? L2

  • A. Side by side, opposite poles facing, with iron keepers
  • B. In a dry box away from heat
  • C. Keeping them near a hot stove
  • D. Storing in a wooden box with proper pairing
Answer: C. Heat demagnetises a magnet. All the other options protect the magnet.

Q3. Reshma keeps her debit card next to a strong magnet for a few days. What might happen and why? L4

The black magnetic strip on the card stores data as tiny magnetic patterns. A nearby strong magnet will mix up these patterns and erase the data — her card may stop working at ATMs and shops.

Q4. Name any THREE uses of magnets in industry or medicine. L2

(i) Cranes with electromagnets lift iron scrap. (ii) Loudspeakers and earphones use magnets to create sound. (iii) MRI machines use very strong magnets to take pictures inside the body. (Other valid: hard disks, motors, recycling sorters.)

Q5. Why are TV screens, mobile phones and watches harmed by strong magnets? L3

These devices contain delicate electronic and magnetic parts. A strong external magnet can disturb images on screens, erase magnetic data (like on a card strip), or magnetise tiny metal parts inside watches — stopping them from working correctly.

Assertion – Reason

Assertion (A): A magnetic compass works even during a cloudy storm at sea.

Reason (R): A compass uses Earth's magnetism, not the stars.

  • A. Both A and R are true, R explains A.
  • B. Both true, R does not explain A.
  • C. A true, R false.
  • D. A false, R true.
Answer: A. Earth's magnetism is always present (day, night, clouds) — this is exactly why a compass is useful in a storm.

Assertion (A): A bar magnet that has been heated strongly loses its magnetism.

Reason (R): Heat disturbs the alignment of the tiny magnetic particles inside the material.

  • A. Both A and R are true, R explains A.
  • B. Both true, R does not explain A.
  • C. A true, R false.
  • D. A false, R true.
Answer: A. Heat scrambles the neat line-up of magnetic particles, so the magnet is demagnetised.

Assertion (A): Credit cards must be kept far from strong magnets.

Reason (R): Credit cards are made of plastic.

  • A. Both A and R are true, R explains A.
  • B. Both true, R does not explain A.
  • C. A true, R false.
  • D. A false, R true.
Answer: B. Both are true, but the real reason is the magnetic strip on the card can be erased — not the plastic body. So R does not explain A.

Next → Part 4: Exercises & Summary

Frequently Asked Questions — Compass, Applications and Demagnetising

What does the topic 'Compass, Applications and Demagnetising' cover in Class 6 Science?

The topic 'Compass, Applications and Demagnetising' is part of NCERT Class 6 Science Chapter 4 — Exploring Magnets. It covers the key ideas of compass, directions, applications of magnets, demagnetising, heat, hammering, storing magnets, explained through everyday examples, labelled diagrams and hands-on activities from the NCERT Curiosity textbook. Class 6 students learn simple definitions, see why each idea matters in daily life, and try short experiments and observations. The lesson uses easy language, colourful pictures and small questions so that young learners build a strong base for higher classes and for competency-based questions in CBSE school tests.

Why is 'Compass, Applications and Demagnetising' important for Class 6 NCERT Science?

'Compass, Applications and Demagnetising' is important because it builds the first ideas of science that Class 6 students will use again in Class 7, 8 and beyond. NCERT Chapter 4 — Exploring Magnets — introduces compass and connects it to things children already see at home, at school and in nature. Learning this topic helps students ask better questions, understand simple news about science, and score well in CBSE tests that use competency-based questions. The chapter also supports NEP 2020 by encouraging curiosity, observation and learning by doing rather than only reading and memorising.

What are the key ideas students should remember from Compass, Applications and Demagnetising?

The key ideas in 'Compass, Applications and Demagnetising' for Class 6 Science are: compass, directions, applications of magnets, demagnetising, heat, hammering, storing magnets. Students should be able to say each term in their own words, give one or two easy examples from daily life, and draw a small labelled diagram where needed. A good way to revise is to make flashcards, write a short note in the science notebook, and solve the NCERT in-text and exercise questions of Chapter 4. Linking every idea to something seen at home or school — in the kitchen, garden, playground or sky — makes these ideas easy to remember for unit tests and the annual CBSE examination.

How is Compass, Applications and Demagnetising taught using activities in NCERT Curiosity Class 6?

NCERT Curiosity Class 6 Science teaches 'Compass, Applications and Demagnetising' through an inquiry-based approach using Predict–Observe–Explain activities. Students first make a guess, then try a small experiment with safe, easily available materials, and finally explain what happened and why. This matches the NEP 2020 focus on learning by doing. For Chapter 4 — Exploring Magnets — the textbook has hands-on tasks, labelled pictures and thinking questions built for Bloom's Taxonomy Levels 1 to 6. Teachers use these activities, along with competency-based questions (CBQs) and assertion–reason items, to check real understanding instead of only rote learning.

What real-life examples of compass can Class 6 students see at home?

Class 6 students can see compass at home in many simple ways linked to 'Compass, Applications and Demagnetising'. Kitchens, school bags, playgrounds, the garden and the night sky are full of examples that match NCERT Chapter 4 — Exploring Magnets. For example, students can look at food labels, watch changes while cooking, try safe activities with water, magnets or shadows, and observe the Sun, Moon and weather each day. Keeping a small science diary — with the date, what was observed and a quick drawing — turns daily life into a mini science lab. These real-life links make concepts easy to remember and help in answering competency-based questions in CBSE Class 6 Science.

How does 'Compass, Applications and Demagnetising' connect to other chapters of Class 6 Science?

'Compass, Applications and Demagnetising' connects to many other chapters in NCERT Class 6 Science Curiosity. The ideas of compass come back when students study related topics like diversity in the living world, food, magnets, measurement, materials, temperature, water, separation, habitats, natural resources and the solar system. For example, what students learn here helps them build mental pictures for later chapters and for Class 7 and Class 8 Science. Teachers often ask cross-chapter questions in CBSE exams to check if students can use what they learned in Chapter 4 — Exploring Magnets — in new situations. This linked approach matches the NEP 2020 and NCF 2023 focus on holistic, competency-based learning.

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