ETCH 213: Electromagnetic Induction and Electromagnetism - Faculty B. Allen - Prof. Bret C, Study notes of Electrical and Electronics Engineering

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Understanding Online Resource for ETCH 213Faculty: B. Allen

Electromagnetic Induction and

Electromagnetism

Online Resource for ETCH 213Faculty: B. Allen Electromagnetism Relates to the magnetic field generated around a conductorwhen current is passing through it.

Left-hand rule Online Resource for ETCH 213Faculty: B. Allen

If the fingers of the left hand are placed around the wire sothat the thumb points in the direction of the electronic currentflow, the fingerswill be pointingin the directionof the magneticfield beingproduced by theconductor.

Magnet Terms Online Resource for ETCH 213Faculty: B. Allen Maxwell – One magnetic line of force or flux iscalled a Maxwell.Magnet Flux (

φ) – The magnetic lines of force produced by a magnet.Weber – 10

8 Maxwells. Flux Density (

β) – A measure of the strength of a wave.Flux Density (

β) = Magnet Flux(

φ)/Area (A)

Online Resource for ETCH 213Faculty: B. Allen

Magnetizing force (H) Magnetizing Force – Also called magneticfield strength, it is the magnetomotive forceper unit length at any given point in amagnetic circuit.

mmf^ l

NI l

H^

×

Reluctance ( Online Resource for ETCH 213Faculty: B. Allen

R)

Reluctance – Resistance to the flow of magnetic linesof force.

Magnetic Reluctance (

R) = mmf/

φ

Measured in Ampere-Turns/Weber

Electric Resistance (R) =V/IMeasured in Ohms

Magnetic Online Resource for ETCH 213Faculty: B. Allen

Permeability (

R) reluctance

Electric

Conductance (G) = 1/ (R) resistance

Online Resource for ETCH 213Faculty: B. Allen Permeabilities of various

materials

Online Resource for ETCH 213Faculty: B. Allen

Remanence or Retentivity – The amount of amaterial that remains magnetized after themagnetizing force has been removed.Coercive Force – Magnetizing force needed toreduce the residual magnetism within a material tozero.

Applications of Online Resource for ETCH 213Faculty: B. Allen electromagnetism Magnetic type circuit breaker

Electric bellRelay

Solenoid-type electromagnet

Solenoid Online Resource for ETCH 213Faculty: B. Allen

Solenoid – A coil and movable iron core that, when energizedby an alternating or direct current, will pull the core into acentral position.

Online Resource for ETCH 213Faculty: B. Allen

Electromagnetic induction Electromagnetic Induction – The voltage produced ina coil due to relative motion between the coil andmagnetic lines of force.Faraday’s Law – When a magnetic field cuts aconductor, or when a conductor cuts a magnetic field,an electric current will flow in the conductor if aclosed path is provided over which the current cancirculate.

Generator Online Resource for ETCH 213Faculty: B. Allen

Generator – A device used to convert a mechanicalenergyinput intoan electricalenergyoutput.

Online Resource for ETCH 213Faculty: B. Allen Parts of a generator Armature – The rotating or moving components of amagnetic circuitStator – The stationary components of a magneticcircuit