The great magnetism test
By
Trevor Stone
MY PROBLEM
by trevor stone
Can you see a magnetic field created by a magnet
To Start my project I read about magnetic and there behaviors and properties.
All about magnets and magnetic fields
1.Ceramic magnets, like the ones used in refrigerator magnets and
elementary-school science experiments, contain iron oxide in a ceramic
composite. Most ceramic magnets, sometimes known as ferric magnets, aren't
particularly strong.
Alnico magnets are made from aluminum, nickel and cobalt. They're stronger than
ceramic magnets, but not as strong as the ones that incorporate a class of
elements known as rare-earth metals.
Neodymium magnets contain iron, boron and the rare-earth element neodymium.
Samarium cobalt magnets combine cobalt with the rare-earth element samarium. In
the past few years, scientists have also discovered magnetic polymers, or
plastic magnets. Some of these are flexible and moldable. However, some work
only at extremely low temperatures, and others pick up only very lightweight
materials, like iron filings.
It takes a little effort for these materials to become magnets. We'll look at
how it happens in the next section. 2. A magnet is any object that has a
magnetic field. It attracts ferrous objects like pieces of iron, steel, nickel
and cobalt. In the early days, the Greeks observed that the naturally occurring
'lodestone' attracted iron pieces. From that day onwards began the journey into
the discovery of magnets.
These days magnets are made artificially in various shapes and sizes depending
on their use. One of the most common magnets - the bar magnet - is a long,
rectangular bar of uniform cross-section that attracts pieces of ferrous
objects. The magnetic compass needle is also commonly used. The compass needle
is a tiny magnet which is free to move horizontally on a pivot. One end of the
compass needle points in the North direction and the other end points in the
South direction.
The end of a freely pivoted magnet will always point in the North-South
direction.
FPRIVATE "TYPE=PICT;ALT=Magnetic Poles"
The end that points in the North is called the North Pole of the magnet and the
end that points South is called the South Pole of the magnet. It has been proven
by experiments that like magnetic poles repel each other whereas unlike poles
attract each other.
Magnetic Fields
What is a magnetic field? The space surrounding a magnet, in which magnetic
force is exerted, is called a magnetic field. If a bar magnet is placed in such
a field, it will experience magnetic forces. However, the field will continue to
exist even if the magnet is removed. The direction of magnetic field at a point
is the direction of the resultant force acting on a hypothetical North Pole
placed at that point.
How is a magnetic field created?
When current flows in a wire, a magnetic field is created around the wire. From
this it has been inferred that magnetic fields are produced by the motion of
electrical charges. A magnetic field of a bar magnet thus results from the
motion of negatively charged electrons in the magnet.
Magnetic Lines Of Force
Just as an electric field is described by drawing the electric lines of force,
in the same way, a magnetic field is described by drawing the magnetic lines of
force. When a small north magnetic pole is placed in the magnetic field created
by a magnet, it will experience a force. And if the North Pole is free, it will
move under the influence of magnetic field. The path traced by a North magnetic
pole free to move under the influence of a magnetic field is called a magnetic
line of force. In other words, the magnetic lines of force are the lines drawn
in a magnetic field along which a north magnetic pole would move.
The direction of a magnetic line of force at any point gives the direction of
the magnetic force on a north pole placed at that point. Since the direction of
magnetic line of force is the direction of force on a North Pole, so the
magnetic lines of force always begin on the N-pole of a magnet and end on the
S-pole of the magnet. A small magnetic compass when moved along a line of force
always sets itself along the line tangential to it. So, a line drawn from the
South Pole of the compass to its North Pole indicates the direction of the
magnetic field.
Properties of the magnetic lines of force
The magnetic lines of force originate from the North Pole of a magnet and end at
its South Pole.
The magnetic lines of force come closer to one another near the poles of a
magnet but they are widely separated at other places.
The magnetic lines of force do not intersect (or cross) one another.
When a magnetic compass is placed at different points on a magnetic line of
force, it aligns itself along the tangent to the line of force at that point.
These are just some of the basic concepts of magnetism. One cannot possibly
grasp the depth and appreciate the versatility of magnets without reading more
about the uses of magnets, the Earth as a huge magnet and electromagnetism among
other things.
the end