fringing effect

It  may be noted that  the  useful flux  while crossing air gap tend's  to bulge  out words as  shown lines  at b;b"  there by increasing  the effective area  of  the gap and  reducing  the flux density  in the air gap this effect is known  as fringing effect 

stroboscopic effect

In any type of discharge lamp the discharge  is actually extinguished twice per cycle and 100  time per second  in 50 hrz 50  these  is a sliaght stroboscopic effect ,the  effect makes  a revolving wheel appear to stand still [or] backward [or] a moving object to appear in a slow 

MAGNETIC HYSTERESIS

magnetic hysteresis
the phenomenon of lagging of flux density   B behind magnetizing  force H in the magnetic material's  subjected to cycle  of magnetization   is known as  magnetic hysteresis

B-h curve and hysteresis

The relation between the magnetic flux density  [B]  and the magnetic force  [h]  is called B-H curve    [or]  magnetizing curve

magnetic leakage[or]leakage

The magnetic flux that does not follow the desired path in magnetic circuit is called leakage flux

thus the ratio of total flux to the useful flux  is known  as leakage co- efficient [lamda]
Leakage flux co-efficient =total flux / useful flux

series magnetic circuit

A  magnetic circuit has a number of part of different materials carrying   the  same magnetic field [or] flux is called a series magnetic circuit  it is also called composite magnetic circuit.

magnetic circuit

  magnetic circuit                                                                                                                                                       The complete closed path followed by the magnetic lines  of force is  called a magnetic circuit 

Reluctivity

Reluctivity:-It is a specific reluctance  and analogous to resistivity in electrical circuit

Permeance

permeance
It is measure of the ease with ,which magnetic flux lines can be established in the material
it is just reciprocal of the reluctance of the material  and is measured in wb/at [or] henry
permeance=1/Reluctance

magnetic flux

magnetic flux  

The total number of  lines  of force set up in  the a magnetic circuit is  called magnetic flux

Reluctance of any part of a magnetic circuit

 Reluctance of any part of magnetic circuit                                                                                                     The ratio of the drop in  magneto motive force to the flux produced  in that part  of the circuit

Reluctance ,S=NI/phi

reluctance [S]

Reluctance is proparty  of the substance ,which opposes the flow of magnetic flux through it
it  is denoted by the letter [S]
measured in AT/wb

magnetizing force [or] magnetic field intensity

Field intensity  at any point  in a magnetic field is  the force acting  on a unit n- pole placed  at that point

it is represented by H
measured in  newton/weber[or] At/M

magnetizing force ,H=m.m.f/mean length
NI/M

pertain to magnetic circuit , magneto motive force [m.m.f]

Magneto Motive Force[m.m.f] :- magneto  motive force is force  which drive [or] tends  to drive is magnetic flux through  a magnetic circuit like  electromotive force  in electrical circuit

m.m.f  =  number of turn's into current

=N into I=NI

force between two parallel current carrying conductor

Ampere
hence one ampere  is defined as that current, which flowing   in two straight parallel  conductor  of infinite length of negligible cross sectional  area ,and placed one meter  apart   in a vacuum  would produce a  force a  force of  2 into 10 power of mines 7   per meter length  

fleming 's left hand rule

Stretch the first finger [fore finger ],second finger [middle finger ]and thumb  of the left hand at right angle to each  other
If the first finger represent  the direction of the main field ,the second finger represent direction of the current  and the thumb  represent the direction  of motion of the conductor

magnitude of force on a current carring conductor in a magnetic field

According to Biot -  savart's law ,The field  strength  a point P  due  to small element D L  of  the conductor  will  be
the corresponding flux density                                                                                                                

  

mechanical force on current carrying conductor in a m.f

If the direction of current is reverced in the conductor
the direction of force experiencd is also reverced

                                                                                                                            

If the conductor is placed  at any angle  [theta]  to the main magnetic field

RELATION BETWEEN BH AND MU R

The flux density b produced in  a material  is directly proportional to the magnetising force H,in other word ,greater the magnetising  force ,greater the flux density .
mathamatically  ,   B  proportional to H 
                                                           

        

                                               

  

FIELD INTENSITY [OR] MAGNETISING FORCE [H]

Field intencity[or] magnatising force:- field  intencity at any  point  in a  magnetic field  is the force  acting on a unit n-pole  placed at  that  point
It is represented by H and measured in newton per/weber                                                                                magnetic field srength

magnetic field  strength

RELATIVE PERMEABILITY

Relative permeability :- The ratio of permeability of a material to the permeability  of free space  is called   it's relative permeability .
it is represented  by the letter

MAGNETIC PERMEABILITY

permeability:-The ability of metirial to conduct magnetic  flux through  it is called permeability of the  meteral
represanted  by greek letter [MU]
Absolute pemeability in a free space  in vacum

  

           

MAGNETIC FIELD

magnetic field

Magnetic field :- The space [or] Rregion around  the magnet  where it  is pole's ehibit  a force  of attraction [or]  repulsion is called magnetic field.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         Magnetic flux :-the total number of line's of   force  in magnetic   field is called the magnetic flux.
                                                                                                                                                                       

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
    It is denoted by greek letter [phi].
    the unit of magnetic flux in  si saystem [weber]
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        Magnetic flux dencity :- magnetic flux dencity at any point is the  magnetic  flux  passing per unit area of   a surface  at right angle to the magnetic field
 it is denoted by the letter[ B ]

HEATING EFFECT OF ELECTRIC CURRENT

a Definate relation  between electrical energy  expanded  and the amount of heat genarated and is called joule 's  law of electrical heating.
this law state that   is the amount of heat[H] Genareted  in a conducter is directly praportional  to the
Square of the current passing [i2]
Resistance of the conductor [R]
Time for  which  the current flow [T]

MECHANICAL AND ELECTRICAL WORK

Mechanical  work                                                                                                                                          mechanical  work is said to be done by[or] against the body when the point of application of a force  moves in [or] oppsite to the direction of applied force                                                                                                                                                            [or]                                                                                    work is said to be done on a body  when force act on it  and the body moves throught a some distance                                   SI unit's -joule's                                                                                                                                             work done =force  into distance                                                                                                                                                                                                                                                                                                                                                                                                                            Electrical  work :                                                                                                                                           Electrical work said to be done in a electrical circuit   when Q ampere's -second's of  electricity posses  through it against the potential difference of  [v] volts's
                               electrical  work =VQ    Q= IT

ELECTRO MOTIVE FORCE[E.M.F] AND POTENTIAL DIFFERENCE

The  Energy required  to drive an  electric current  in a circuit is known as electro motive force [E.M.F] .         The potential defference between two point in an electric circuit  tend's cause flow of electric current between that two point                                                                                                                                    Both electromotive force  and potential defference  measured in  volt's[ v ]

ONE AMPERE CURRENT

One ampere  current i is said to flow through a wire , when  a charge  of one coulomb flow in  one second

law of resistance

1.  Directly proportional to  it's lentgth                                                                                     inversely proportional to it's area of crosssection                                                                depend's upon the nature of material                                                                                Depends upon  the temparature