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76.
!.. ~.. : ~:n.u_---J
. I,
.. . . 1
\1agneuG---r-'
SlrUClure ! .
1
. ,I,
;
-'I~m-
I I
.' I
\ 0-0
N. '"'',,,:-] , <<m
. I i ..
---I ",;m~
LJ-+ x
l~cm
j ---L.
J
. i
-I cm-
LJ
FIGUP.E2.6
",oçnepc
Sy\~mler
.~omple :2,;
I ~ .
Ir
Ironbar
11em
'.
'.0
:~
.~.
.-
F!GUP.E2'.7
~:e(::~CM.ncic;
C,,:;,Iier'~e .
i.loçne!;ce:c;;"
Given1('\rl;~re
2.6 .
in thecoilsO'lhallhe iron bar remainssuspendeuaI auislance011cmusing(a)
induclanceand (bJ lhe iielus concepl. AIso calculmelhe \:nergy.slored in lhe....
magnetictielu.The relativepl:rmeabiiilyanu lhe specificgravily01'lhe magnetic :-'~~l
struqwreanolheironbar.afe:!~()(.)<il1d7;85gJcm).r~spectiv~ly.:-.ícgloCIleakage~J.}'
andfringin!!.e.ffecls. . .. . :.,"..
.' .[(-
50il;r:on. . . .. . t~.
(aI Siticelhe permcabililY~flhc'magncticcircui'lis givento beconstant.;h~..~~
induclanceconccplfor.determininglheforce'expericncedbytheironbarcanbe .~.
employed.LCIUSasslimelhal lhedisla!1Cebelwecnlhefronbarandlhe remaining.'"
magnelic-.:ircuilis.I'metcrs.TI]Cmeanlengih01'eilherlhe lefl 01'lhe righl leg01'
lhe magneticcircuit. I,. inc1uuínglhe pan nf lhe irõn.baLcan be compuleuas
0.1'6m.anólhalôflhecenterleg.I,..is0.055m.Theerfe.cli\'cequi\'alentcircuit ....
in termsoi lhereluclancesis shownin Fig:2.7.where. .
(1)1\=., 0.1~.._,. ... ;o 636.620 H'"
.ir..'=~;;!
.I'
10:'" x 10-.. -;'.958 X IO~.\'H - I
1 _ 0.1155 _,,,,. _I
.J, - '~lJOO;..J-;r '< IÜ-- x 10-. - _18.~,)8H
Thedfecti\'<:r.:luctance01'each,)1'lhe outer legs,i~
.11" ;o .:li" - :;1~ ;o 636.620-'- 7.958 :<10"'xH-I
The\Vlalrclu'tanccis
.;1
. .~.. =,)54.')~O- 11.l)~7, 10".1I1 -,
. I.\AGNETIUIELDENE!\G'(CONVEI\SION 77
Theinuuclanceis
N2 .1
L ;o - ;o H-I
;J/. 1.I93.iOOx- 95.4.9
FromEq.(2.32).
Thenegative'signonl)'indicateslhall~eforceis actinginlheupwarddirection.
Fprx =.1cm.lhedevelopedforcebecomes ".
Thisi'orcemustbcbalancedbylherorceduetogravilyactingin thedo.wnward.
Jirectionontheironbar.Thus.
F'I ;o rrrg .. 7.85x 10-J x 1i x 1 x 9.81';00.8.h~
Therefore. I = 0.8~7\0.00412'= 1-1.34A
1heinC:uctance,')['lhecjj'cuitatx =.I emis L = 83.11fJ.H.Theenergyslored
in lhe magnelicliclu is
w.,... ~.Ll~ ..0.5 x 83.1'1x 10-6x 14..34=8.55mJ
tb\ Fie'" cOllcepr:Thetluxin lhecemcrkg I11USlb~'twic.:as l11uchas Ihal in
any on\:01'lh.: oUlcrkss. as shown'in Fig. 2::~:Ir lJn is the Ilux d.:nsityin lhe