Fun With Magnets: CBSE Class 6 Science Chapter Guide

What Are Magnets? From Natural Rocks to Fridge Doors

Legend has it that a shepherd named Magnes in ancient Greece discovered a strange rock. The nails in his sandals and the metal tip of his staff got stuck to it! This mysterious rock, which contained a natural magnetic material called magnetite, was the world's first known magnet. Magnets found in nature like this are called natural magnets.

While natural magnets are fascinating, they are often weak and have irregular shapes. So, humans learned to make their own magnets, which are called artificial magnets. These are much stronger and can be created in various useful shapes. You've probably seen many of them! Common shapes include:

• Bar Magnet: A long, rectangular bar.
• Horseshoe Magnet: Shaped like the letter 'U'.
• Cylindrical Magnet: A round, rod-like magnet.
• Button Magnet: Small, flat, and circular, often used in crafts and on fridges.

These are made from materials like iron, nickel, and cobalt.

Understanding Magnetic and Non-Magnetic Materials

Magnetic Materials

These are materials that get attracted by a magnet. The most common examples are iron, nickel, and cobalt. Your steel spoon or a safety pin are magnetic!

Non-Magnetic Materials

These materials are not attracted by a magnet. Examples include plastic, wood, glass, rubber, and aluminium. A plastic ruler or a wooden pencil will not stick to a magnet.

The Golden Rules of Magnets: Poles, Attraction, and Repulsion

• Every Magnet Has Two Poles: No matter the shape, every magnet has a North pole (N) and a South pole (S). The magnetic force is strongest at these poles.
• Attraction and Repulsion: This is the most important rule! Opposite poles attract each other (North pulls South). Like poles repel each other (North pushes North away, and South pushes South away).
• The Directive Property: If you hang a bar magnet freely from a thread, it will always come to rest pointing in the North-South direction. The end pointing to the Earth's geographic North is the magnet's North pole.
• Poles Always Exist in Pairs: You can never have a magnet with just one pole. If you break a bar magnet in half, you don't get a separate North and South piece. Instead, you get two new, smaller magnets, each with its own North and South pole!

Activity: How to Make Your Own Magnet

1. Step 1: Gather Your Materials — You will need an iron object like a sewing needle or a long nail, and one strong bar magnet.
2. Step 2: The 'Single Touch' Method — Place the iron needle on a flat surface like a table. Take one pole of the bar magnet (for example, the North pole).
3. Step 3: Stroke the Needle — Place the magnet's pole at one end of the needle. Without lifting it, stroke it along the entire length of the needle until you reach the other end.
4. Step 4: Lift and Repeat — Once you reach the end, lift the magnet high up and bring it back to the starting point. DO NOT drag it backwards along the needle. Repeat this stroking motion, always in the same direction, about 30-40 times.
5. Step 5: Test Your Magnet — Your needle is now a temporary magnet! Test its power by bringing it close to some small iron pins or paper clips. They should get attracted to the needle.

Exam Tip: How to Care for Magnets

Remember that magnets can lose their magnetism! This is called demagnetisation. This can happen if they are:

• Heated: Strong heat scrambles the magnetic particles inside.
• Hammered: Hitting a magnet hard can weaken it.
• Dropped: Dropping a magnet repeatedly, especially from a height, can cause it to lose its properties.

To keep magnets strong, store them properly. Bar magnets should be stored in pairs with their unlike poles side-by-side, separated by a piece of wood. A soft iron piece, called a 'keeper', should be placed across the ends.

Practice Questions with Solutions

• Q: What happens when the North pole of a magnet is brought near the North pole of another magnet? What about North and South poles? A: Step 1: Recall the rule of magnetic poles. Like poles repel each other, and unlike poles attract each other. Step 2: When the North pole of one magnet is brought near the North pole of another magnet, they are like poles. Step 3: When the North pole of one magnet is brought near the South pole of another magnet, they are unlike poles. Final answer: The North pole of a magnet will repel the North pole of another magnet. The North pole of a magnet will attract the South pole of another magnet.
• Q: Name two magnetic materials and two non-magnetic materials. A: Step 1: Identify materials that are attracted by a magnet as magnetic materials. Step 2: Identify materials that are not attracted by a magnet as non-magnetic materials. Final answer: Magnetic materials: Iron, Nickel. Non-magnetic materials: Wood, Plastic.
• Q: How can a freely suspended bar magnet be used to find directions? A: Step 1: Understand that a freely suspended magnet always aligns itself in a specific direction. Step 2: A freely suspended bar magnet aligns itself approximately in the North-South direction. Step 3: The end pointing towards the North is its North pole, and the end pointing towards the South is its South pole. Final answer: A freely suspended bar magnet always rests in the North-South direction. By knowing the North direction, other directions (East, West, South) can be determined.
• Q: Describe a simple method to make a temporary magnet using an iron nail. A: Step 1: Take an iron nail and a bar magnet. Step 2: Rub one pole of the bar magnet along the length of the iron nail from one end to the other, lifting the magnet each time and repeating the process in the same direction for 30-40 times. Final answer: Rub one pole of a bar magnet repeatedly (30-40 times) in the same direction along the length of an iron nail. The nail will become a temporary magnet and can attract small iron objects.

Frequently Asked Questions