Fun With MagnetsBhavya Mohindru

Magnets

A magnet is a material or object that produces a magnetic field.

This magnetic field is invisible.

But it is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.

Discovery It is said that, there was a shepherd named Magnes, who lived in ancient Gr

eece.

He used to take his herd of sheep and goats to the nearby mountains for grazing. He would take a stick with him to control his herd. The stick had a small piece of iron attached at one end.

One day he was surprised to find that he had to pull hard to free his stick from a rock on the mountainside. It seemed as if the stick was being attracted by the rock. The rock was a natural magnet and it attracted the iron tip of the shepherd's stick. It is said that this is how natural magnets was discovered.

Magnetite/ Lodestone In Magnesia, rocks contained large numbers of black stones which

had the power to attract peices of iron.

The Black Stone came to be known as Lodestone or The Leading Stone because of the way it could be used to find directions.

Today, it is known as the mineral magnetite ( Fe3 O4 ) and is found in many countries.

Magnetic & Non - Magnetic Substances Materials which get attracted

towards magnets are called Magnetic Materials, for example, Copper, Iron, Nickle.

Magnets can attract or repel other magnets and can attract any magnetic material even if it is not magnetised.

Non - Magnetic materials, Such as wood, paper, plastic & most metals, don't get attracted towards magnets.

Test For Magnetism : Compass We can use a compass to find out wether a substance is magnetic

or not.

One end of the compass needle normally points to north. If a magnetic substance comes close to needle, it will make the needle turn.

Test For Magnetism : Repulsion Take a metal & a known magnet.

Bring one pole ( N or S ) of a magnet near the ends of the metal bar one by one.

If both ends of the magnet get attracted towards the metal bar, the bar is not a magnet.

If one end attracts and the other repels the metal bar is a magnet.

Magnetic Compass The magnetic compass functions as a pointer to "magnetic north",

the local magnetic meridian, because the magnetized needle at its heart aligns itself with the horizontal component of the Earth's magnetic field.

The magnetic field exerts a torque on the needle, pulling one end or pole of the needle approximately toward the Earth's North magnetic pole, and pulling the other toward the South magnetic pole.

The needle is mounted on a low-friction pivot point, in better compasses a jewel bearing, so it can turn easily.

When the compass is held level, the needle turns until, after a few seconds to allow oscillations to die out, it settles into its equilibrium orientation.

Attraction & Replusion Two magnets will be attracted by

their opposite poles, and each will repel the like pole of the other magnet.

An Isolated Magnetic Pole Does'nt Exist The Magnetic Poles always exist in pairs.

When an attempt is made to separate the magnetic poles by breaking a magnet , the it is observed that the two parts become a complete magnet.

New magnetic poles are developed at broken ends.

Thus, an isolated magnetic pole does not exist i.e each magnet is dipole.

Uses Of Magnets It is used in a Compass to find directions

It is used in factories for lifting heavy masses of iron.

It is used by surgeons in hospitals to remove steel splinters from the wounds.

It is used in construction of telephones, electric bells etc.

It is used to separate iron & steel from non-magnetic materials.

And Many many more.....