MagnetismSTEM Workshop

Dr. Tracey Wheeler

What is magnetism?

Magnetism is the force of repulsion and attraction between two different substances caused by the motion of charged particles.

The Law of Magnetic Attraction

O Force (push or pull) of a magnet is the strongest at it ends, which are called poles.

O North-seeking- points to earth’s north pole

O South-seeking-points to earth’s south pole.

O When the two unlike poles attract and two like poles repel- law of magnetic attraction.

Magnetic Field

O Space around the magnetic also acts like a magnet which is a force referred to as a magnetic field.

O The direction of the magnetic field is the direction in which the north pole of a compass needle points when it is placed in the magnetic field.

O Magnetic fields can be represented by magnetic field lines which are imaginary lines that indicate the direction and strength of the magnetic field.

O Magnetic field lines form closed loops and never cross.

Is this a misconception?

O A magnetic field is a pattern of lines that surround a magnet- Why or Why Not?

Force of MagnetismO Magnetism is the result of the spinning

movement of the electrons in the atom. O Atoms of nonmagnetic materials- half of

electrons spin in one direction, half in the opposite direction- cancels the magnetic effects.

O Atoms of magnetic materials- more electrons spin in one direction than the other- making the atom a tiny electromagnet.- atoms group together (domains) line up in north and south seeking poles.

O When opposite poles of a magnet are brought together, the lines of force join up and magnets pull together.

Magnets

O Natural magnet (ex. Lodestone) has many poles.O Ferromagnetic substances-spontaneous magnetism

exists in the substance even in the absence of a magnetic field.

O Examples-iron, steel, cobalt, nickel, and a few rare elements dysprodium and gadolinium can be made into magnets

O Magnets are attracted to metals that contain ferrous, mainly iron and steel.

O Artificial magnets can be made from ferromagnetic substances. Sometimes aluminum when mixed with nickel and cobalt.

Lodestone

MisconceptionOAre all metals

attracted to magnets?

OExamples?

Permanent MagnetsO Permanent magnets are often

made from steel- iron-carbon alloy.

O Electrons align themselves and spin in the same direction while orbiting their nucleus. This produces a small magnetic field. As more electrons align themselves, the magnetic field becomes stronger. In the case of permanent magnets, electrons tend to stay aligned, unless heated temperature and then cooled.

Misconception or Reality?

Permanent magnetics can be made by placing them in a strong magnetic field

Magnets losing their magnetism

O Dropping or striking them

O 2. heating themO 3. placing the north

seeking poles side by side or on top of each other. The molecules will be thrown out of alignment.

Keep magnets strongO Piece of soft iron across the

poles of a U shape magnetO Attach magnets to a metal

surfaceO Store them in pairs with

opposite ends attracting separated by nonmagnetic divider (wood, plastic)

O Disk or ring magnets pairs with opposite poles together

Misconception

OLarger magnets are stronger than smaller magnets

Maglev

O Maglev (magnetic levitation) vehicles are trains that are lifted, propelled, and guided by fast-moving magnetic fields. Speeds 248 mph or more.

O Use linear electric motors built into the guideway to generate a magnetic field that attracts the vehicle, allowing the train to move