1/8-12 Magnets

Natural magnetic material

Lodestones

Permanent magnets

Induced magnets

All known magnets have 2 poles

• North Pole - defined as the direction the south pole of a compass point to

• South pole - defined as the direction the north pole of a compass point to

North is attracted to

South (Opposites attract)

The North geographic pole is attracted to the

North magnetic pole

North geographic pole is the

South magnetic pole (and vice versa)

Magnetism acts through

magnetic fields

• They extend towards infinity

• Are a vector sum so there is only 1 net magnetic field at any given point in space

• Similar to electric fields

“Lines” are actually

closed loops

• The direction always

  • Leaves from magnetic north

  • Enters from magnetic south

• They follow the north pole of a compass

Electric fields exist because

a charge exists

Magnetic fields exist when

2 things happen

• A charge exists

• The charge must move

Any moving charge produces a

magnetic field

Unpaired electrons create

magnetism (like iron)

Magnetic Domains are

tiny volumes with the same magnetic field direction

The bigger the domain

the stronger net magnetic field, meaning the magnet is stronger

Since magnets are just magnetic fields,

you cannot separate N from S

Ferromagnetic

• “Normal magnet” - Permanent magnets

• Many lone pairs

• Can form large, permanent magnetic domains

• Can be made permanent

• AlNiCo, NdFeB (neodymium), iron

Paramagnetic

• “temporary only”

• Attracted to the source of magnetic field

• Have lone pairs that produce a net magnetic moment

• No large, permanent magnetic domains

• Can not be made permanent

• Many chemicals, magnesium, lithium

Diamagnetism

• All materials are diamagnetic (frogs, papers, magnets, humans, copper)

• Repelled from the source magnetic field

• Very weak, dominated by other magnetisms

magnets can only interact with

other magnets

No matter how you set it up,

magnetism must be perpendicular to a plane

Up

+z

Down

-z

West

-x

East

+x

North

+y

South

-y

q(moving v)

magnet

B

magnet (source)

Like Torque, components of velocity and magnetic field must be

perpendicular to produce a magnetic field

Thumb is

force

Index finger is

current or velocity

middle finger is

magnetic field

Right hand for

current

Amperes Law

gives the relationship between the current flowing