Magnets: Summary Note For MCQ(Entrance Preparation)

🧲 Summary Note: Magnets

Here is a clear and concise summary note for the lesson “Magnets”, designed for SEE graduates preparing for NEB Grade 11 Science entrance exams.

📘 What is a Magnet?

A magnet is an object that can attract materials like iron, nickel, and cobalt. It produces a region around it called a magnetic field, where magnetic forces can be felt.

🧭 Types of Magnets:

Natural Magnets: Found in nature (e.g., lodestone). Weak and irregular.
Artificial Magnets: Made by humans. Strong and available in various shapes.

📐 Common Shapes of Artificial Magnets:

Magnets

Bar magnet
U-shaped magnet
Horseshoe magnet
Cylindrical magnet

🌍 Magnetic Poles:

Every magnet has two poles: North (N) and South (S).
Like poles repel, and unlike poles attract.
Poles always exist in pairs—they cannot be isolated.

🧲 Magnetic Field:

The region around a magnet where its force can be felt.
Represented by magnetic field lines:
- They go from north to south outside the magnet.
- They are closer where the field is stronger.
- They never cross each other.

🧪 Properties of Magnets:

Attract magnetic materials (iron, cobalt, nickel).
Poles always appear in pairs.
Magnetic force is strongest at the poles.
If suspended freely, a magnet always aligns in the north-south direction.
Heating, hammering, or dropping a magnet can weaken or destroy its magnetism.

🧲 Magnetisation and Demagnetisation:

Magnetization	Demagnetization
Making an object magnetic (e.g., by rubbing with a magnet)	Removing magnetic properties (e.g., by heating or hammering)

🔄 Temporary vs Permanent Magnets:

Type	Description
Temporary Magnet	Acts as a magnet only when near a magnet or current (e.g., an iron nail)
Permanent Magnet	Retains magnetism for a long time (e.g., bar magnet made of steel)