fy.chalmers.sefy.chalmers.se/~faldt/I2 08 lv 7 del 1.pdf · 22. A rectangular coil with resislance...
7
2. gn Y ·ko.C1!11.rukt.i•.•n 1ul!' tn: idtmliskn 10, O cm tii!1ga kopparlx.+n I>om har IvåNinittsan:n.C1 J,Okv;j.oratr:entimcter. Tva av t~n~n iir förhunånu (i toppen nll Y:etJ med ett aluminiumblock, van; massa iir "0,0 kg. Dcttn,dje blmets ånde haHs vid kmpt,rature-n :20 grader Ce1siul>.Hda i\uordningcn befinner sig i vakuum och strå!ningsförluskma kn!1 rönmmmas. Dessutom görs approxjmationen ntt den ~t1t.~gi "nm åtgår ror att varmn upp kopparbenen kan försummas. Hur lån.g tid Inr det for a!uminiumblO\~kd MI.nå t~'mpcraturt!n 60 grnder C<:1"1u" mu dess bt:gyn.nels~!empt!rntur ih' 100 gradcr' Celsius? ~u ••uu •••••••••••••••• __ ._u~# •.••• •._·· _ I lir"( :i ,/ j ( u~··7m_. .) 'i-l" ~, _ .~J.. ~,~:. s-_.~ r' ..... Å ·S '-r ... , ,OJ' ' •..•.•. il 0vI·, ,'," ,><-t., , O : '~oJ J /~]" lA.. -:-. "I"S> '''.tl ~'4.. \ l 'iJU(l _0\ '" ! ~ J At (> - . ,~, .••. ~ ,.. ~- "'t' & tr'-Tb\ _ ....•... _~_ .... "",-">-""'0," t..J 'o .".• ~"<(14..,....,1- •••.1-) ~]~-1.·w,-" c"" r. \::-e"~·"'e .••.. , Ii \, ". .0. " <;."'" .. ~ .s '" 1,0 (:"", -r. C' !t) el'f,. 5;;~<.c.,~"'~V.,A: q-J I\~.. f.ot~r...t.<.~ .• l·,. \.t: •." f "=-'''4-l' •.. iV'"-' ~ .•.. f··:"'·V~.,r· "<J"\~'f,o"""''' ·'·'f~""'·/rO-l't· .. f "i~ .,t, ~~Q. '" ,'.,. <:.. dl' ~)-d'-i''''~ -v_,,- iF ..~ \ ,. ~.~~ . t: "'_.. :;$. "'(:. t ....... i~A~ T-:I~ T t. 'u 't.Q .__,L:~.?~~,~;o~~o._ - ~. -'t<.<t) • t,c .• :;:.·· <., «.() - t.:::> ;(>0 -1-.<,
Transcript of fy.chalmers.sefy.chalmers.se/~faldt/I2 08 lv 7 del 1.pdf · 22. A rectangular coil with resislance...
2. gn Y ·ko.C1!11.rukt.i•.•n 1ul!' tn: idtmliskn 10, O cm tii!1ga kopparlx.+nI>om har IvåNinittsan:n.C1 J,Okv;j.oratr:entimcter. Tva av t~n~n iirförhunånu (i toppen nll Y:etJ med ett aluminiumblock, van; massaiir "0,0 kg. Dcttn,dje blmets ånde haHs vid kmpt,rature-n :20grader Ce1siul>.Hda i\uordningcn befinner sig i vakuum ochstrå!ningsförluskma kn!1 rönmmmas. Dessutom görsapproxjmationen ntt den ~t1t.~gi "nm åtgår ror att varmn uppkopparbenen kan försummas. Hur lån.g tid Inr det fora!uminiumblO\~kd MI.nå t~'mpcraturt!n 60 grnder C<:1"1u"mu dessbt:gyn.nels~!empt!rntur ih' 100 gradcr' Celsius?
~u ••uu •••••••••••••••• __ ._u~# •.••• •._·· _
Ilir"( :i
,/
j
( u~··7m_..) 'i-l"~,_ .~J..~,~:.s-_.~
r'.....Å ·S
'-r..., ,OJ'
' •..•.•.il 0vI·, ,'," ,><-t., , O
: '~oJ J /~]" lA..
-:-. "I"S> '''.tl ~'4..
\ l'iJU(l _0\ '" !
~
J At(>
-.,~,
.••.~ ,.. ~- "'t'
& tr'-Tb\_ ....•... _~_....
"",-">-""'0," t..J
'o .".•~"<(14..,....,1- •••.1-)
~]~-1.·w,-" c"" r. \::-e"~·"'e.••..,Ii
\, ". .0. " <;."'"
.. ~.s '" 1,0 (:"",
-r. C' !t)el'f,.
5;;~<.c.,~"'~V.,A:q-J I\~..f.ot~r...t.<.~.•l·,. \.t: •." f "=-'''4-l' •..iV'"-'
~.•..f··:"'·V~.,r· "<J"\~'f,o"""''' ·'·'f~""'·/rO-l't· .. f"i~ .,t,~~Q. '" ,'.,. <:.. dl' ~)-d'-i''''~-v_,,- iF
..~ \ ,.
~.~~ .
t: "'_..:;$. "'(:. t.......
i~A~T-:I~
T t. 'u 't.Q
.__,L:~.?~~,~;o~~o._- ~. -'t<.<t) • t,c .• :;:.··<.,
«.() - t.:::>
;(>0 -1-.<,
7. Ett klut ilV Ilran haT mdien R" l 00 mm. På. grunn av kl:rvning avatomktknor genereras värmt: unitormt ihdn kJotF.l W alt vatjcsd<l\tld utvecklas 70 m.Tfmol. Vm.1l har viirmelf'dningslölTu<\gan46 WI rn K.Hur ~t<)rblir t<:m}'<'Tat\lTskil1nnd"o rudJan klotets cCnl.nun ochdess periferi?
). =. ~{. \V! •.••...\••..
!Z...,. tt>() IM"""
I'f"""t. '" "I" ",,:vJ
'" __ 14". ':\ . \0 O t...~I"""~" , V'.oI.~\.","':"\...r· \..~ -= .t.J P •.••.
~.l./-.... ~1(.-) =
I , ,_, ••. ~.O.• , _~(. ~- -t"'t\.~"""
S \,I(",)~. 3J ~'''!1('.
~ ..(.:1''t'V''' .••
~("I +rr~:J..f- ---- - - __ o
.• Nf1 - J. ""'.•..I-!>_ .N",
~" j ~ l.$>
l~~·<.t. ~f htA..\, u t ,.('C I..l••..'" ":J I~." •••....\ v••..<>l,~...•.. ,. t'(~.\":: h(~\ ;;;-~~..... ~.-...................................•...........•... - --- -......•.--..-- ----
,..,. ')<1 , "l',d..- i.. =' t;. {·r·, 1::.- _ Å.. "'':T" (' "t. . _
. J, .. o .J
.. .\.
..~~:!..~~..t.__{~~j._~. ~'«.-h::s.....•..", . kl 1\
~;'~~~ . ':
~.. 1 / ••.•.~·.)t_;..~ : ~.
,~(tf ......••~....•-. ,.~ . y...,.•• ~ .••,. ,\j." ~
~?.,~~..:2.~:<~' .~~:.~.:.C~!?~~_:·..~.)...~_;. .f.:\.1'.;,~L",-to (. A_~ ••• t.,':) ~.
20.49
Två kondensatorer med kapacitanserna 25,0 mikrofarad och 5,00mikrofarad parallellkopplas och laddas upp med hjälp aven lOO-voltsspänningskälla.Rita kretsen och beräkna den totala energin som är lagrad i de tvåkondensatorerna.Hur stor skulle potentialskillnaden kondensatorerna om de hade kopplats iserie om de skulle innehålla lika mycket energi som i det föregående fallet?
Lösning:
,6\J Jl
~--+Cs c.\ct.
c, . c~
~s",o. S', ()t)=' Cs-= -=
c,--+c""t,.'Jo, o
c(
Dvrr -i I
fJ F -;::
Cl.
~,\1- ~r\ "L
W= \ .i.. °d'" _b \J
u=-- C A'\J~.6\J -= C2J
. ~(ITo (O
(8Jö \.J -
•
:')li. For the fU. circuit shown in Figure P2:t:F" lel Ihe inductamT be :tOo H, the resistance 8.00 n, and the ballel)' emf:~(;.Ov. (a) Ca\culate the "uio of the potential difference
across the resistor to the voltage across the inductOl' whenIhe cUITent is 2.00 A. (b) Cakulale the voltage ,Kross Iheinduclor whcn Ihe CUITenl is 4.50 A.
s
R
1-
:)1\. When the switch in Figure P2~35 is closed, Ihe CUlTenllakes :HJO ms lo reach 98.0% of ils final \~Ilue. If R = lO.!) n,whal is Ihe induclancc?
t../.,... -,
T-::.T [\-e..I
"""A )i
\
'...J
t -=. "3.00 """J
'.T -= O,<\S> IW\A )(. L
R..
\~\c.-\- ~t",~"'z~'s1I\a ~ b I- u(f';:' d .!""- IL ". J1 -1:""", •
\ --t
-=)
'3 -'3 -~L- lO\) lD -:::j\b1·IC .s-
\V\ o,<>'tR.
L-:: '\'-R
~ 1-\-61-~
':\\{,'\~'i-=)10' \0-=
40. One application of an HL ciln.it is the gcncration of tilllcv,nying high voltage from a low-voltage sOllrce as shown in
Figure P2:~.4(). (a) What is thc ClIlTent in the circllit a longtilllc after the switch has beell in positioll a? (b) Now Iheswitch is thrown Cjllickly frolll a to h. COlllpnle the iIIitiaivoltage across each resistotO alld ;\Cross the indllctor.(c) How IIInch tillle elapses bcfore the voltage across thcindllctor drops to I~.()V?
Il s
1200V+'1~ ~oOOII
~I • 1200Q
.•..
+- R 'l....•.'v-12.0n
J:-~J~':".'-J~.s-\~VV'
,kw:...b c..----~JS,
'L.; -\ -4 ""'"0..)
, •"o.n ~ """"~
~
1.2" o 1,0 AI-=- --= -- A-=
Rt..
\ 2.., o
b)
S-;: 1-+.s, 'L{lo, fOS1 D •...•
I =' 1100 A
e
6\J t.. := \!.. \J
6'\11... -::: ',00\"z..oO = If-ec V
6\JL = \[00 -+ \t... -= \l....f..\ V
A
11..,0
IV')
- ~/'I'e..
\L. \ i.,~
\"t\'"t\<.
~oo I I~, \ '"1t.\'1. \1..
23.43En spole med luftkärna har 68 varv och längden 8,00 cm och diametern1,20 cm. Hur mycket energi är lagrad i den om strömmen är 0,770 A?
Lösning:
E. = -:LR + L. dId-t
_"' 't dT_) LE.. = I ~ -+ L~ 6t-
1 \
L
e f fc4-.l-utv.•• ,)pO\~
efTeto"jlC\lel-e"~d
ON Coct Hca.-.-" ~
,= €.<A e J 1 \/\ J6v<-'\ " ,f"f O Ie.<---'\ ~
dU(5dI.
~, = L'l'- dO () =- L:t. . d..:t~ ~+d.-ttJa
I
~ \u€ = ~ LI ~Ju~ == S dUC
=-5 L"J: ' cCr
o
o
Sfole..v.J
iV\.. d~k +Q:.-v\ I
dct>edI: I\J ~BE=--N-- L-~L=--- -
cif d-+ IN
cp AJ l-\,~ ~ pö -l I ~t3 = ~D -T
L.
tv" t:..
f-J fJ o ~ • I fJo N A = .5\~I p I-(->. L - - l~ - I'l
\ ~ T -=--> u~ = ~ Po ~
'l... L) _ b
6 8 • en . ",0<' () ~ ~_ - /', ~~ . lOJ\ - ':\ • ,T IU I
= J...., 4\\· lO o l o ~()o _
22. A rectangular coil with resislance N has N turIIS, each of
length e and width tv as showlI iII Fig;lre P23.22. The coilmoves iI1lo a IInifi)J"Jn magnetic fidd B with constalIt vcloc
ity v. What are the magnit\\{le and direction of the tOlalmagnetic force on the coil (a) as it enlel's the magncticfield, (b) as it 1l1OVCSwithin the field, and (c) as it leavesthe field?
~
IDI--c---1
Bin,x
x
xx"xxx
x
XX
X
XXXXX
X
XXXXXX
L"..- , ,c. J """ V\ \ '~-0..)
•. ,I ~~A.r .5p~\~ko\,..oV\~,"",O"",,-r,k_A-~d131 •..•
\ V\.d~L~ •....•••.J
€-V\st..-t"'~.$'O~1ft.\.. •••.lMt> hJ 4LI lA.. "'-<;~~ 'Je...... CJJ
d v')
e-L. f-e, :V\..J~'-\. ..h_ I-<:). ,
S"r () \ ~~lZ .h.A- J~'tA "'-"-\
R/\
(- )( )
E.. = IR
c. d.qSe 13'c:::... -:;..1.1 - -:::t-Jw' V ,'-"dt
c...)
klA- Sfö'~\
~ •..J IN 'r B l hA---=)QgLt.o", J ~, '" V\..Q..\
-d
T-=-O -=)F-::.O~ N CA...
,IV\...dl,.A..c.e~ ~ ..N~~
"O
,X - f$0""""'-cr-r Q L-1-IN\.~"""~ j..~ L
~a
-Ul- )(
\J "'J"
.1..
S6VV\~ v-i ~h f-I"""
J~~
P<t(fVC-~
,
x.
ISf al e-
~
I '3 ' ...s -t r;:V'-'\ ""'" .e---.,\~-1
)i-
I-
ri'-'\.+\..- d'\
0.-_I.stn:-"""" ~
'M.t....d \J Y";/ .
,
-r~ 'f~
,\ CJ -
CA.)- \
