Physics - Chpt 7 Magnetism

magnetism

anything that attracts iron, cobalt, or nickel

3 types of Magnets

Natural, artifical perminant, and electromagnet

Natural magnet

Earth and loadstone

Artificial Permanent Magnets

bar or horseshoe of iron that became magnetized

Electromagnets

temporary magnet produced by an electric current

Law of Magnetism

opposite poles attract and like poles repel

Magnetism can be attributed to the property of

electron spin

Magnetic element

has more electrons spinning in one direction than the other

What two states can a magnetic element exist in?

nonmagnetic and magnetic

Billions of dipoles occur in ______ in which all dipoles are aligned in the same direction.

domain

Non-magnetic element

type of material that doesn't have the ability to become magnetized

electron spins cancel each other out

Surrounding every magnetic there is a zone of influence called

a magnetic field

Magnetic field lines

the closer the lines are together the stronger the magnetic field

What is another term for Magnetic field?

Lines of force

What is the rule for lines of force direction?

outside move from the north to south, and move from south to north

If two magnets have lines of force moving in the same direction

they will repel eachother

The strength of the magnetic field is proportional

to the number of lines per centimeter

Magnetic Induction

how a magnetic element can be changed from the non-magnetized state to the magnetized state

If you bring a magnetic element near a pole

the side nearest to the pole assumes the opposite pole

Permeability

the ease of which a material can be magnetized

High permeability

ease to magnetize

low permeability

difficult to magnetize

Retentivity

the ability of a magnet to resist demagnetization

High retentivity

hard to demagnetize

Low Retentivity

easy to demagnetize

The relationship between permeability and retentivity

High Permeability and low retentivity

Low Permeability and high retentivity

Ferromagnetic

strongly attracted by a magnet

ex: iron, cobalt, and nickel

Paramagnetic

weakly attracted by a magnet

ex: platinum

Nonmagnetic

are not attracted by a magnet

ex: wood, glass and plastic

Diamagnetic

are repelled by a magnet

ex: beryllium and bismouth