Magnetism

Branch of Physics deals with Relationship of Electricity/Magnetism

Magnetic Field Always Surrounds Conductor With Flowing Current

Field Only Exists While Current Flows

Left Thumb Rule: Wire Held in Left Hand

Thumb Points Direction of Current ( + or - )

Fingers Encirlcing Wire Indicate Direction of Magnetic Lines Around Current

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

3 Ways To Induce An EMF

Wire May Move Across Stationary Flux

Flux May Move Across Stationary Wire

Flux May Vary In Strength While Stationary Wire Lies Within It

Magnitude : Size of Induced EMF

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

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

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

Number of Turns In Conductor Coil

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

Induced EMF Is Directly Proportional To # of Turns In Coil

Magnetic Flux : Magnetic Lines of Force

Electromagnet

Helix =Wire Coil

Solenoid : Helix Carrying Current

Solenoid With Iron Core=Electromagnet

Natural

Lodestone (Iron Oxide)(Magnetite)

Artificial Permanent

Compass Needle

Alnico - Alloy of Aluminum, Nickel, and Cobalt

Many Times Lifting Capacity of Steel

Electromagnets

Two Poles

North

South

Like Repel / Unlike Attract

Force of Attraction / Repulsion Does NOT Follow Inverse Square Law

Ferromagnetic - Strongly Attracted

Ex: Iron, Cobalt, Nickel

Ex: Alnico - Alloy of Aluminum, Nickel, Cobalt

Paramagnetic - Feebly Attracted

Ex: Platinum

Non-magnetic

Ex: Wood,Glass,Plastic