NCERT Exploring Magnets Summary - Class 6 Science - Fully Solved Notes For Students

Introduction

Magnets are objects that can attract certain materials such as iron. People have used magnets for navigation and simple experiments for many centuries. Magnets are found in many everyday items such as toys, pencil boxes, refrigerator magnets, school supplies, loudspeakers and electric motors.

Magnets may be natural or artificial (man-made). Natural magnets include lodestones (naturally magnetised pieces of iron ore). Artificial magnets are made by humans from materials such as iron, steel and some alloys. Artificial magnets can be shaped as bars, horseshoes or needles and can be permanent or temporary depending on how they are made and used.

Magnetic and Non-magnetic Materials

• Magnetic materials: These are attracted towards a magnet. Common examples are iron, nickel and cobalt. Small objects made of these metals, for example paper clips or iron filings, are pulled by a magnet.
• Non-magnetic materials: These do not show attraction towards a magnet. Examples are wood, plastic, rubber and glass. These materials do not get pulled by a magnet under normal conditions.

Poles of a Magnet

• Every magnet has two poles: a North Pole and a South Pole.
• The magnetic force is strongest near the poles of a magnet.
• If you cut a magnet into two pieces, each piece becomes a smaller magnet with its own North and South poles. Therefore, a single isolated pole (monopole) cannot be obtained by breaking a magnet.

Finding Directions

• A freely suspended bar magnet (for example, hanging from a string or balanced on a pivot) always aligns itself in the north–south direction because the Earth behaves like a huge magnet.
• The end of the magnet that points towards the north is called the North-seeking pole and the end pointing towards the south is called the South-seeking pole.
• The property of a magnet to align with Earth's magnetic field is used in the magnetic compass. A compass contains a small, magnetised needle that can rotate freely and show directions.

Making a Simple Compass

1. Magnetise a steel needle by rubbing it repeatedly in one direction along a bar magnet. This process transfers magnetism to the needle.
2. Float the magnetised needle on a small piece of cork or wood in a bowl of water so that it can rotate freely.
3. The needle will come to rest pointing roughly in the north–south direction; the end pointing north is the North-seeking pole of the needle.

• Ancient Indians used a navigation device similar in principle to a compass called the Matsya-yantra, which was a fish-shaped magnet floated in oil to show directions.

Comparison Between a Freely Suspended Magnet and a Magnetic Compass

• Working: Both a freely suspended magnet and a magnetic compass align with Earth’s magnetic field. A freely suspended magnet demonstrates the basic property of magnetic alignment, while a compass is an instrument designed to show direction reliably.
• Practical use: A compass is portable and fixed for practical navigation. A freely suspended magnet is useful for experiments and for learning the basic behaviour of magnets.

Attraction and Repulsion Between Magnets

• Unlike poles attract - a North pole of one magnet attracts the South pole of another magnet.
• Like poles repel - North repels North and South repels South.
• The presence of repulsion is useful to identify whether an object is a magnet. A non-magnet will only be attracted; it will not repel a known magnet.

Magnetic Effect Through Materials

• Magnetic force can act through certain non-magnetic materials such as wood, cardboard, plastic or glass. For example, a magnet held under a cardboard sheet can still pick up a paper clip placed on top of the sheet.
• This shows that magnetic effects are not always stopped by thin non-magnetic barriers; they can pass through some materials, though the strength may reduce with distance and material thickness.

Fun with Magnets

• Move steel balls or pins through a maze by holding a magnet under the maze board.
• Pick up paper clips from water without touching them by using a magnet from below the water container.
• Make toy cars with magnets so that they either repel (push apart) or attract (stick together) depending on pole alignment; this demonstrates repulsion and attraction in a playful way.

Care of Magnets

• Do not drop, hammer or heat magnets because such treatment can reduce or destroy their magnetism.
• Store magnets properly to keep them strong. Keep bar magnets in pairs with opposite poles on the same side so the magnetic circuits close and they lose less strength.
• Place a small wooden piece between paired magnets and use soft iron keepers across the poles when storing strong bar magnets; this helps maintain their magnetism for a longer time.

Key Points

• Magnetic materials: Iron, Nickel, Cobalt.
• Non-magnetic materials: Plastic, Wood, Rubber, Glass.
• Every magnet has two poles - North and South.
• A freely suspended magnet comes to rest in the north–south direction.
• Compass needles show directions because they are small magnetised needles free to rotate and align with Earth’s magnetic field.
• Like poles repel and unlike poles attract.
• Magnetic effects can act through non-magnetic materials such as cardboard, wood and glass.

Summary: Magnets are useful objects that attract certain metals and help us find directions. They have two poles, show attraction and repulsion, and can be used in many simple activities and devices such as compasses. Handle and store magnets carefully to keep them strong and useful.