Magnetism

Magnets• What is a magnet?

– An item that exhibits magnetism– What is magnetism?

• A property of matter in which there is a force of attraction or repulsion between unlike or like poles

S N

N SS N

S N

What are magnetic poles?• Often referred to as the north and south ends

on a magnet• Defined as the two ends of a piece of

magnetic material where the magnetic forces are strongest– Like magnetic poles repel and opposite magnetic

poles attract

Review• Which group of transition metals exerts a

magnetic field?– Iron Triad - Iron, Cobalt, and Nickel– What is a magnetic field?

• The region around the magnet where magnetic force act

– This sounds very similar to an electric field!!!!!!

How are electricity and magnetism similar?

• For each, as the distance between the objects decreases, the attraction/repulsion increases or as the distance increases, the attraction/repulsion decreases

Greater Attraction or Repulsion

Lesser Attraction or Repulsion

Do only the metals in the iron triad posses magnetic properties?

• Only a few materials show strong magnetic properties – Iron Triad– Items made with these metals are known as

permanent magnets

• However if you bring a magnet near or in contact with specific items (such as paper clips and nails) you can produce a temporary magnet– Why is this?

Magnetic Domain

• Explains the grouping of atoms in an object • Defined as groups of atoms with aligned

magnetic poles

The domains are randomly arranged in an unmagnetized object

In a magnetized object, the domains are aligned

Can permanent magnets lose their magnetism?

• Yes, but not all of there magnetic properties– If the permanent magnet is dropped or heated the

atoms will somewhat realign themselves due to jostling or particle acceleration