MAGNETISM, IT’S SO ATTRACTIVE!!

WHAT ARE MAGNETS?

A magnet is an object that attracts (brings near) minerals/metals such as iron, nickel, cobalt and steel. The ends of a magnet are called poles. A magnet has a north pole and a south pole. Opposite poles attract; the north pole of one magnet attracts the south pole of another magnet. Like poles repel (move away from); the north pole of one magnet pushes away the north pole of another magnet.

Properties/qualities/ characteristics of a

magnet:

Magnetic Field

What are some common uses for magnets?Did you name some?

Polarity

Repel Attract

Their ability to react to electrical charges

Magnets are everywhere

Types of Magnets

Permanent Magnet: An object that keeps its magnetism after it has been magnetized.

Temporary Magnet: A magnet that does not keep its magnetism.

These are the most common type of magnets that we know and interact with in our daily lives. The magnets on our refrigerators. These magnets are permanent in the sense that once they have been magnetized they retain a certain degree of magnetism. Permanent magnets are generally made of ferromagnetic material. ( Ferro means iron, and its origin is from Italy.) Such material consists of atoms and molecules that each have a magnetic field and are positioned to reinforce each other.

Temporary magnets are those that simply act like permanent magnets when they are within a strong magnetic field. Unlike permanent magnets however, they loose their magnetism when the field disappears. Paperclips, iron nails and other similar items are examples of temporary magnets. Temporary magnets are used in telephones and electric motors amongst other things.

NATURAL MAGNET:

SUBSTANCES MADE OF AN IRON MATERIAL

THAT IS NATURALLY MAGNETIZED BY THE EARTH’S MAGNETIC

FIELD. MAGNETITE OR LODESTONES

Compass: an instrument used to determine geographic direction on Earth.

History of Magnets

Types of Magnets

Shape & Configuration Permanent magnets can be made into any shape imaginable. They can be made into round bars, rectangles, horseshoes, donuts, rings, disks and other custom shapes. While the shape of the magnet is important aesthetically and sometimes for experimentation, how the magnet is magnetized is equally important. For example: A ring magnet can be magnetized S on the inside and N on the outside, or N on one edge and S on the other, or N on the top side and S on the bottom. Depending on the end usage, the shape and configuration vary.

Disc Magnet

Horse Shoe MagnetU-shape Magnet

Cow Magnet

Ring Magnet

s

Rod Magnet

Domino Magnet

Certain metals are attracted to magnets:Iron, Nickel, and

CobaltThe swirling flow of molten iron and nickel around Earth's solid center triggers an electrical current, which generates the planet's magnetic field. Remember the Earth’s magnetic field goes from pole to pole, the same shape as a bar magnets field.

Magnets attract and repel

Repel (Push apart)

Attract (draw together)

Magnetic force: the push or pull of a magnet on another magnetic material.

MAGNETIC FIELD THE MAGNETIC FORCE THAT EXISTS AROUND A MAGNET

PolarityA compass tells you what direction is 'North', but have you ever wondered how it can do that? The answer has to do with something called magnetism. Every magnet produces an invisible area of influence around itself. When things made of metal or other magnets come close to this region of space, they feel a pull or a push from the magnet. Scientists call these invisible influences FIELDS. You can make magnetic fields visible to the eye by using iron chips sprinkled on a piece of paper with a magnet underneath.

MAGNETIC FIELD OF VARIOUS TYPES OF MAGNETS:

EARTH’S MAGNETIC FIELD The magnetic field of Earth is caused by currents of electricity that flow in the molten core. These currents are hundreds of miles wide and flow at thousands of miles per hour as the earth rotates. The powerful magnetic field passes out through the core of the earth, passes through the crust and enters space. This picture was created by a computer from a mathematical model, shows the solid inner core region (inner circle) surrounded by a molten outer core (the area between the two circles). The currents flow in the outer core, and the lines of force shown in yellow, travel outwards through the rest of Earth's interior. If the earth rotated faster, it would have a stronger magnetic field. If it had a larger liquid core it would also have a stronger magnetic field. By the time the field has reached the surface of earth, it has weakened a lot, but it is still strong enough to keep your compass needles pointed towards one of its poles.

Neato Magneto

ELECTROMAGNETISM

Electromagnetism is magnetism that is produced when an electric current passes through a wire coiled around an iron core.

SuperconductorsThese are the strongest magnets. They don't need a metal core at all, but are made of coils of wire made from special metal alloys which become superconductors when cooled to very low temperatures.

Electromagnets

Make your own electromagnet

Permanent Magnets compared to Electromagnets

Flow of Electric CurrentThe magnetic

field ceases with an on/off switch.

Made from a coil of wire and an electric power source.

No electric current needed.

An electro magnet runs on electricity

Always have a magnetic field, hence permanent

Fixed magnetic strength

strength of an electromagnet can be adjusted by the amount of electric current that flows.

Permanent magnet loses its magnetic properties, as it does by heating to a high temperature, it will be rendered useless for ever.

Creates a magnetic field.Used for the benefit of man.

EFFECTS OF MAGNETS ON THE NEEDLE OF A COMPASS

Compass: an instrument used to determine geographic direction on Earth.

Magnets effect the needle only at close distances. Magnets close to a compass overrides the Earth’s effect on the needle.Point the Way

EFFECTS OF EARTH’S MAGNETIC FIELD ON THE NEEDLE OF A COMPASSThe Earth’s magnetic field effects the needle at great distances.Where Am I really?

REAL-WORLD APPLICATION1. MRI and other uses of magnets in the medical field.2. When would you want a metal not to be a magnet? 3. Mechanics use for magnets, how would this be useful?4. Magnets are now being used to clean fish tanks. How?5. How do hikers use a compass and a map?6. How do pilots use a compass to navigate?7. Compare and contrast life on the North and South Poles. 8. What does the saying, “opposites attract” mean?9. Discuss how high-speed trains in Japan and Germany use

magnets to operate. The trains are magnetically propelled across the tracks at a

very high speed of up to 500km per hour.10. Miss Valora uses a magnet in her summer job in Alaska. 11. Where do we see electromagnets in use in our daily lives?12. Iron in our diet, is it important? What are other ways for

scientists to separate mixtures besides using magnets?

Reading Comprehension ReviewResearch and Report