Magnetism-psg

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Magnetism

Magnetic Classification

Non-magnetic

Ex: Wood,Glass,Plastic

Paramagnetic - Feebly Attracted

Ex: Platinum

Ferromagnetic - Strongly Attracted

Ex: Alnico - Alloy of Aluminum, Nickel, Cobalt

Ex: Iron, Cobalt, Nickel

Retentivity = Ability of Magnet to Resist Demagnetization

Permeability = Ease Which Material Is Magnetized

Laws

Force of Attraction / Repulsion Does NOT Follow Inverse Square Law

Like Repel / Unlike Attract

Two Poles

South

North

Magnets

Electromagnets

Artificial Permanent

Alnico - Alloy of Aluminum, Nickel, and Cobalt

Many Times Lifting Capacity of Steel

Compass Needle

Natural

Lodestone (Iron Oxide)(Magnetite)

Ability of Certain Materials To Attract Iron, Cobalt, or Nickel

Electromagnetism

Electromagnet

Helix =Wire Coil

Solenoid : Helix Carrying Current

Solenoid With Iron Core=Electromagnet

Magnetic Flux : Magnetic Lines of Force

Branch of Physics deals with Relationship of Electricity/Magnetism

Elctromagnetic Induction

Moving Magnetic Fields Induce Electron Current

When Conductor (Wire) Cuts Across Magnetic Flux (or Is Cut By Magnetic Flux) An EMF [ Electromagnetic Force] or Potential Difference is Induced In Conductor

Flux Line : Interaction Between A Single Loop Conductor and A Line of Force

Magnitude : Size of Induced EMF

Number of Turns In Conductor Coil

Induced EMF Is Directly Proportional To # of Turns In Coil

Lines of Each Turn of Coil Are Additive = More Flux Linkages Per Second

Angle Between Conductor/Magnetic Field

As Angle Approaches 90 Degrees

Space Between Lines of Force Become Smaller

More Flux Lines Are Cut Per Second

Larger EMF Is Induced

Strength : Stronger The Magnetic Field, The Higher The Induced EMF

Speed : More Flux Lines Cut Per Second, Higher The Induced EMF

3 Ways To Induce An EMF

Flux May Vary In Strength While Stationary Wire Lies Within It

Flux May Move Across Stationary Wire

Wire May Move Across Stationary Flux

Magnetic Field Always Surrounds Conductor With Flowing Current

Field Only Exists While Current Flows

Left Thumb Rule: Wire Held in Left Hand

Fingers Encirlcing Wire Indicate Direction of Magnetic Lines Around Current

Thumb Points Direction of Current ( + or - )