magnetism

any ______ ______ in motion creates a magnetic field these magnetic fields interact with each other

charged particle

imaginary lines of a magnetic field are always _____ _____

closed loops

with an electron circling a nucleus the magnetic field lines will always be _____ to the plane of motion

perpendicular

protons and electrons are charged particles when they move they generate a _____ ____

magnetic field

electrons behave as if they rotate on an axis clockwise or counterclockwise this rotation causes property known as _____ _____. this also induces a magnetic field

electron spin

magnetic fields are ______ meaning there is a north and south pole

dipolar

small magnet created by electron is called _____ ______

magnetic dipole

an accumulation of many dipoles aligned creates a _____ _____ when this happens it acts like a magnet

magnetic domain

when acted on by an external source or artificially induced magnetism randomly oriented dipoles will _____ with the magnetic field. this is basis for MRI

align

when an external source like a strong magnet is applied the dipoles will line up with that external magnetic field. when enough align the material gets a north and south pole and behaves as a magnet this is known as ______ ________

induced magnetism

three principle types of magnets

-naturally occurring magnets

-artificially induced permanent magnets

-electromagnets

this is the best example of a naturally occurring magnet. it has a magnetic field because it spins on its axis. (also has a molten iron core which moves with the spinning)

earth

this is a natural magnet. it is naturally magnetized pieces of magnetite. found in the earth and have strong magnetic properties due to being within the earth’s magnetic field for a long time becoming permanently magnetized.

Lodestones

this type of magnet is available in many sizes and shapes but principally as bar or horseshoe shaped magnets that are usually made of IRON

artificially produced magnets

this is an example of an artificial permanent magnet

compass

what makes magnet a ____ ______ is that their dipoles (domains) were forced to become aligned by exposing the material to strong external magnetic field.

permanent magnet

permanent magnets magnetic property can be destroyed by _______ the magnet or _____ it with a hammer. this causes magnetic domains to be jarred from alignment

heating the magnet (heat causes atoms to vibrate)

hitting it with a hammer

can all metals become a permanent magnet?

no.

this type of magnet can be turned on or off via electricity. it consists of a wire wrapped around an iron core. The electric current runs through the wire and a magnetic field is created. the magnetic field intensity it proportional to the current

electromagnet

matter can be classified by four interactions or states of matter with an external magnetic field

-non magnetic

-diamagnetic

-paramagnetic

-ferromagnetic

this applies to many materials. it is when they are unaffected when brought into a magnetic field.

non-magnetic

name two nonmagnetic materials

wood, and glass

these materials are weakly repelled by either magnetic pole when brought into magnetic field. cannot be artificially magnetized.

diamagnetic

name three diamagnetic materials

plastic and water and copper

these materials are strongly attracted to a magnetic field and can usually be permanently magnetized.

ferromagnetic

name three ferromagnetic materials

iron, cobalt, nickel

this alloy is one of the more useful magnets produced from ferromagnetic material. made of aluminum and nickel. retains magnetism even when heated.

alnico

these materials are somewhere between ferromagnetic and non magnetic. they are slightly attracted to a magnet and loosely influenced by an external magnetic field (only lasts when external magnetic field is present, loses magnetism when it is gone)

paramagnetism

name one material that is paramagnetic

gadolinium used in mri

this is the degree to which a material can be magnetized. (iron would be high) (wood low)

magnetic susceptibility

when iron is placed in magnetic field it increases the strength of the field so it has high _____ _____ wood does not increase the strength of the field so it has low _____ _____

magnetic susceptibility

there is a smallest unit of magnetism true or false?

false. when you divide a magnet you just make a smaller magnet. there is no separating the north and south pole.

every magnet has a north and south pole this is analogous to ____ and _____ electrostatic charges

positive and negative

like magnetic poles _____ unlike magnetic poles _____

repel, attract (just like positive and negative electrostatic charges)

these are the imaginary lines of the magnetic field they leave the north pole of the magnet and return to the south.

lines of induction (or flux lines)

the intensity of flux lines are ____ to the intensity of the magnetic field. more lines that are packed together= ____ magnetic field

proportional, more lines packed together means stronger field.

what is the SI unit of the magnetic field

Tesla. one Tesla= 10,000 Gauss

earth at the surface is ____ Tesla. Mri is ___-___ tesla

.0005 tesla. MRI 1.5-3 Tesla

like electrostatic charges some materials can be made magnetic via _______. ex if you have soft iron and bring it near magnetic field the lines of induction are altered, attracted to the soft iron and the iron is made temporarily magnetic

induction

most ferromagnetic material when removed form magnetic field does or does not? retain its strong magnetic property

does not

this is a good temporary magnet since it will become a magnet during induction as long as magnetic field is in vicinity

soft iron

if copper was brought into a magnetic field would it become magnetic by induction?

no. copper would not it is diamagnetic

what are two things that can be done to have ferromagnetic materials retain their magnetism when removed from external magnetic field to become permanent magnets?

properly temper the material with heat

leave it exposed to external magnetic field for a long time

intensity of magnetic force is ______ to product of the magnetic divided by the square of distance between them

proportional