Geeta)

Magnetism, an aspect of electromagnetism, one of the fundamental forces of nature. Magnetic forces are produced by the motion of charged particles such as electrons, indicating the close relationship between electricity and magnetism. The unifying frame for these two forces is called electromagnetic theory (see Electromagnetic Radiation). The most familiar evidence of magnetism is the attractive or repulsive force observed to act between magnetic materials such as iron. More subtle effects of magnetism, however, are found in all matter. In recent times these effects have provided important clues to the atomic structure of matter.

In this theory connection between electricity and magnetism, was followed up by the French scientist André Marie Ampere, who studied the forces between wires carrying electric currents, and by the French physicist Dominique François Jean Arago, who magnetized a piece of iron by

placing it near a current-carrying wire.

Michael Faraday made significant contributions to the study of electricity and magnetism. He found that a current flows in a wire that is moved through a magnetic field. The discovery of this phenomenon, which is called electromagnetic induction, contributed to the development of Maxwell’s equations, and led to the

invention generator.

of

the

electric

Magnetic fields influence magnetic materials, and also influence charged particles that move through the magnetic field. Generally, when a charged particle moves through a magnetic field, it feels a force that is at right angles both to the velocity of the charged particle and the magnetic field. Since the force is always perpendicular to the velocity of the charged particle, a charged particle in a magnetic field moves in a curved path. Magnetic fields are used to change the paths of charged particles in

devices such accelerators spectrometers.

as and

particle mass

Magnetic Pole, either of two locations on the surface of the earth where the direction of the earth’s magnetic field is vertical.At a magnetic pole, the magnetic field is vertical and the compass needle does not indicate any particular direction along the ground.

From any point on earth, a compass can be followed to the north and south magnetic poles.

There are two types of magnetic poles:1.North Pole 2.South Pole At the north magnetic pole, the magnetic force is downward, into the ground. At the south magnetic pole, the magnetic force is upward, out of the ground. The north magnetic pole is located by following the

north-pointing end of the compass needle. The south magnetic pole is located by following the south-pointing end of the compass needle.

The magnetic poles are located at considerable distance from the geographic poles, which are the ends of the axis that the earth revolves around.

MAGNETIC LEVITATION TRAIN.

1. When a magnet is suspended freely, it always points in a particular direction. 2. Like poles repel each other and unlike poles attract each other. 3. Magnetic pole always exists in pairs.

1. 2. 3.

Diamagnetic Substances Paramagnetic Substances Ferromagnetic Substances

1. Diamagnetic Substances: The substances which are feebly magnetized in a direction opposite to that of magnetizing field in which these are placed are called diamagnetic substances. E.g. Copper, Gold, Mercury etc.

2. Paramagnetic substances: The substances which are feebly magnetized in a direction of magnetizing field when placed in it are called paramagnetic substances. E.g. Manganese, Platinum, Aluminum, Chromium, Oxygen etc. 3. Ferromagnetic substances: - The substances which are strongly magnetized in the direction of magnetizing field in which they are placed are called ferromagnetic substances. E.g. Iron, Cobalt, Nickel etc.

Solenoids with soft iron cores are called electromagnet. Electromagnets are used to lift very heavy loads in industries in the form of EOT (Electrical Overhead Traveling) cranes.

The phenomenon, by virtue of which changing magnetic field produces induced current, is

known as electromagnetic induction.

BY Mrs. Geeta(Science Mistress) SCHOOL: - GOVT. GIRLS SEN. SEC.SCHOOL, THE MALL.