JOURNAL OF SCIENCE OF HNUE Interdisciplinary Sci , 2014 Vol 59, No 1 pp 37 49 NGHIEN CUU NGUYEN TAC CAU TAO VA HOAT DONG CUA AMPE KE VA VON KE THEO CON D U 6 N G T H I ^ T KE TRONG DAY HOC VAT LI 6 L[.]
Trang 1Interdisciplinary Sci., 2014 Vol 59, No 1 pp 37-49
NGHIEN CUU NGUYEN TAC CAU TAO VA HOAT DONG CUA AMPE KE VA VON KE THEO CON D U 6 N G T H I ^ T KE TRONG DAY HOC VAT LI 6 L 6 P II TRUING TRUNG HOC PHO THONG
Nguyen Ngpc Hting
Khoa Vdi li, Trudng Dai hoc Suphgm Hd Npi
Tom tat Bai bao trinh bay viec to chflc cho hpc sinh ldp 11 nghien cflu nguyen tac
cau tao, hoal dong cua ampe kl va vdn kl theo cac giai doan cua con dUdng thill
kl nham phat buy linh tich cUc, phat trien nang lUc sang tao ciia hoc smh
Tit khda: Ampe ke von ke, day hoc Vai li Vat li 11, con dudng thill ke, tich cUc,
sang tao
1 Mot dau
L/ng dung ki thuat ( U D K T ) ciia vat li la mdt trong nhflng loai kiln thflc cd ban ma hpc sinh (HS) cln linh hpi trong hoc tap vat li d trudng phd thdng Day hoc UDKT cua vat li dupe tien hanh theo hai con dUdng: I/Tim hieu ban than thill bi ki thuat (TBKT), nguyen tac cau tao, boat dpng cua nd va di tdi lam sang td cd sd vat li cfla TBKT (con dudng I) hoac 2/ hUdng din HS dfla tren nhflng kiln thflc, ki nang da cd thilt kl, chi tao TBKT ed mpl chflc nang nao dd (dap flng dupc mpl yeu clu ki thuat xac dinh) giai quylt mot nhiem vu cu the trong san xuat va ddi sdng (con dudng 2- con dudng thilt kl) Viee nghien cflu UDKT cua vat li theo eon dfldng 2 cd lac dung rat Idn doi vdi viec phat trien tfl duy khoa hpc - ki thuat cua HS
Ampe k l va vdn kl la nhflng dung cu do (DCD) dupc HS sfl dung Ihudng xuyen irong cac thi nghiem (TN) Viec d l cap nguyen lac cau tao va hoat ddng cfla chung la can thilt Day la L/DKT cua vat li phu hdp de td chflc cho HS nghien cflu iheo con dfldng 2 ciia day hpc UDKT cfla vat 11
2 Npi dung nghien CIJ:U
2.1 Tien trinh nghien ciiu chung cua HS ve nguyen tac cau tao, hoat dong
cua ampe ke va von ke
Dua vao tiln trinh chung khi nghien cflu mpl L/DKT cua vat li theo con dudng 2 liln trinh nghien cflu cfla IIS ve nguyen tac cau lao hoal ddng cua ampe kl va vdn ke diln
Ngay nhan bill, 15/07/2013 Ngay nhandang 15/12/2013,
Trang 2ra theo cac giai doan sau:
2.1.1 Lam nay sinh van de can giai quyet
- Tren cd sd nghien cflu li thuyet va thflc nghiem ve viec mSc dien kl (G) vao doan mach dien can do 1, U, di tdi nhan xet: G cd gidi han do (GHD) I, U xac dinh va vi G co dien trd nen viec mac G vao doan mach dien lam giam gia tri I, U can do
- Tfl dd, nay sinh vin dl (VD) cSn giai quylt la: Cd each nao de lam giam anh hUdng cua G den phep do I, U khi mac G vao doan mach dien va md rdng dUpc GHD I, II cfla G?
2.1.2 Suy doan va thflc hien giai phap giai quyet van de (GQVD)
Bang lap luan (suy doan giai phap - SDGP) va sau dd, tinh toan cu the (thUc hien giai phap - THGP) tfl cac kiln thflc da biet vl mach dien mdt chilu, di tdi cSu tra Idi cho
ca 2 cau hdi tren:
- can mac sdn (s) song song G biln nd thanh ampe k l va can mac dien trd phu (Rp) ndi tiep vdi G, bien nd thanh vdn ke
- Mudn GHD I(U) cua G tang len n(m) Ian ihi s mac song song G phai cd Ry ^
— ^ va Rp mac noi tiep G phai ed Rp = (m - 1) Rj,
2.1.3 Kiem nghiem nhoi TN tinh diing dan cua ket luan da rut ra ve viec lam tang GHD cua G
- Dua vao cac bieu thflc tren, cho bill Rg, tinh gia tri R,(Rp) can mac song song (noi lilp) vdi G de biln G thanh ampe kl (von kl) cd GHD I (U) gip n (m) Ian GHD I(U) cua G va tinh cac gia tri lo(Ug) Ung vdi cac gia tri I.^(U\) khac nhau
- Thiet ke mach dien va tiln hanh TN de xac nhan cac gia tri Ir,{Up) da tinh dUOc tfl cac bieu thflc
2.1.4 Lam nay sinh VD can giai quyet tiep
Vl moi s (moi R^) mac song song (noi tilp) vdi G cd gia tri R.s(Rp) nhat dinh nen GHD 1(U) cua G chi dflpc tang len tdi mdt gia trj xac dinh VD cin giai quylt tiep la: Lam thi nao de GHD I(U) cua G dupc md rpng tdi cae gia tri khac nhau, nghia la ampe
kl (vdn kl) cd nhilu thang do khac nhau''
2.1.5 Suy doan va thiTc hien giai phap GQVD
- Dfla vao cae bieu ihflc tinh H, va Rp, dua ra giai phap: Mudn ampe kl (vdn ke)
cd nhilu thang do khac nhau ihi phai mac song song (ndi tiep) vdi G cac s (cac Rp) cd R^Rp) khac nhau
- Thilt kl cac mach dien noi G song song vdi cac s (d ampe kl) sao cho R, 6 thang
do 1 Idn hdn R, d thang dd thfl hai dl GHD I khi dung thang do thfl nhat nhd hdn GHD I khi dung thang do thfl hai cua ampe kl va ihilt kl cac mach dien ma cac Rp dUdc mic ndi lilp vdi G (d vdn kl) sao cho Rp d ihang do thfl nhat nhd hdn R^ d thang do thfl hai de
Trang 3GHD U khi dung thang do thfl nhat nhd hdn GHD U khi dung thang do thfl hai cua vdn
kl
2.1.6 Kiem tra tinh dung dan cua cac ket luan da rut ra ngay tren DCD
Md rnat sau cua ampe ke (vdn kl) thflc hanh de xac dinh each mac cac s (cac Rp) vdi G va khang dinh tinh dung dan cua cac kit luan da nit ra
2.2 Cac giai doan nghien ciiu nguyen tac can tao va hoat dong cua ampe
ke theo con ditcfng thiet ke
2.2.1 Nghien cu:u li thuyet va thuc nghiem ve G thuc hanh do cudng do dong dien (I) de lam xuat hien VD can giai quylt
(Lam thi nao de lam giam anh hfldng cua G den gia tn I cln do khi mac nd vao mach dien can do I chay qua va md rdng dUdc GHD I cua G?)
Hinh l.Gdo\ (a) vd mach dien cda G (b)
- Tim hieu G do I (Ifmh la): DUa vao quan sat mat ngoai va ben irong G, hay xac
dinh chflc nang (do I mdt chilu) kieu cd cau do (kieu tfl dien bang khung quay), mach dien cua G (Hinh lb), cac thdng sd ciia G: cac thang do (khi dung hai chdt ( - ) va (OQ)
hay ( - ) va (GO, G cd cung mdt thang do -3aO/j.A - 0 ~ 300//A), GHD (Imax = 300//A)
gia iri cua moi dp chia tren tflng Ihang do (1()//A}, cap chinh xac ciia G (sai so he Ihdng ciia phep do I do G gay ra), chilu quay cua kim chi flng vdi tflng trfldng hdp Giao vien (GV) bd sung Ddn vi I (khdng dupc ghi tren mat G) la /tA sfl dung G d hai chdt ( - ) va (Go) khi tiln hanh TN de phat hien 1 gay bdi cac U nhd nhu ddng nhiet dien, ddng cam flng dien tu cdn d hai chdt ( - ) va (G i) khi tiln hanh TN de phat hien cac
I nhd nhung U khdng nhd, nhfl mach cau Uytxidn Iflc chfla can bang
- Nghien cflu li thuyet ve anh hfldng cua G den gia tri I can do Ap dung dinh luai
Om doi vdi loan mach (Hinh 2) dc thay rang: Viec mac G vao mach dien can do I lam cho gia tri I do dUdc sai lech (nhd hdn) so vdi gia tn thUc cfla I can do (1 doc dudc tren
-.- < Ith
Trang 4Hinh 2 Do I nhd G
- Nghien cflu thUc nghiem ve anh hfldng cua G din gia tri I can do: Lap mach dien nhu Hinh 3 Dich chuyen biln trd de thay ddi UAB- Lfng vdi mdi UAB fJoc sd chi cfla Gi khi chfla mac G2 va khi mac ca Gi va G2 vao doan mach AB, de thay S6 chi cua Gi khi mac ddng thdi ca Gi va G^ ludn nhd hdn sd chi cua Gi khi chi mac Gi
I-Hinh 3 Kiem nghiem dnh hudng cua G den I can do
Nhfl vay, nghien cflu II thuyet va thflc nghiem deu din tdi nhan xel: Khi mac G vao mach dien can do I, G da lam giam gia trj I can do, gay sai so cfla phep do I va mdi G chi
cd mdt GHD lo xac dinh
VD can giai quylt la: Lam thi nao de lam giam anh hudng cua G den phep do I (lam giam sai sd cfla phep do I) khi dung G va cd each nao de cd the sfl dung G do dfldc I
cd cfldng dp Idn hdn IQ (tflc la md rpng dfldc GHD cua G)''
2.2.2 Suy doan va thuc hien giai phap GQVD nhb suy luan li thuyet (SLLT) tuf cac kien thufc da bict
- Suy doan giai phap GQVD
+ Tfl bieu thflc I = : - ^ , thay: De lam giam anh hudng cua G din gia tn 1 can do, phai lam giam Rg, sao cho Rg < R Lfng vdi G da cho (R^ nhlt dinh), cd the lam giam R DCD (DCD) bang each mac dien trd phu song song vdi G
+ Cung cd the sfl dung giai phap mac dien trd phu song song G de chi mdt phln ddng dien chay qua G, !„ khdng vUdt qua lo, phan ddng dien cdn lai {I - IQ) di qua dien trd phu (chia dong) Nhd do ma DCD cd the do dUdc I > I,,
- Thuc hien giai phap da suy doan
Ap dung dmh luat Om cho doan mach mac song song cac dien trd khi mac dien trd phu (cdn gpi la sdn) song song vdi G, biln nd thanh ampe kl (Hinh 4), cd
R^R
- , thay RA < Rg, RA < R.: s lam giam R cfla DCD va do dd, lam
- R A
R^ + R,'
Trang 5Hinh 4 Cdu tao cua ampe ki
cua G, lam cho ampe kl do dfldc I^ax gap >i lln in td' da ma G do dUdc
I
+ Muon GHD I cua G tang len n Ian (n
-R,
) thi s mac song song vdi G phai cd
+ NIU R^ cang nhd so vdi Rg thi RA cang nhd, anh hudng cua DCD den gia iri 1 cln do cang nhd va GHD (n) cua ampe kl cang Idn
2.2.3 Kiem nghiem nhd TN tinh dung dan cua ket luan da rut ra ve vice lam tang GHD cua G bang each mac s song song v6i G
- Dua vao bieu Ihflc linh R^, tim dd Idn K, phai mac song song vdi G do 1 da lim
hieu khi dung hai chdi ( - ) va (G|) debien G thanh ampe kl cd GHD \„^,,^ ^- 3()mA cho
biel Rj = lOOfi, Ro = 2400n? (Vi R^ = - , biel khi diing hai chot (—) va (Gi)
thi Rj = RG -I- Rii = 2600n 1A„„;, = 30mA lg„„„ = 300;/A nen R^ = 2 6f!)
U
- Difa vao bieu thiJc 1 —, tinh cac gia tri 1 iJng vdi l,\i
0, 2A, la,, = 0,3A va IAJ ^ - 0, lA
O-IA 1A2
Hinh 5 Kiem nghiem cdc gid tri l^ dd tinh dttoc
' Thiel ke mach dien va tien hanh TN de kiem nghiem cac gia tn Ig da linh duoc 111
li thuyet: Lap mach dien nhlt Hinh 5, trong do G duoc diing vdi hai chfil ( ) va ( d ) , R dllcJc tao ra nhd dien trd cd cac vach mau de tien hanh TN kiem nghiem cac gia tri 1,, da tinh diJOc Cac day noi phai cd dien trd nhd Kgt qua TN cho IhSy Cac Ij, doc dUdc tren G
Trang 6trung vdi cac Ig da tinh dUdc
- Nlu vSn dung mat chia dp cua G do I lam mat chia dp cua ampe kl mdi dUdc tao thanh bdi G va s da mac, xac dmh thang do mdi va gia tri cua mdi do chia tren thang do nay? (Vi I = nig nen sau khi mac them s cho G, neu vSn dung mat chia dp cua G de dpc I
do dUdc thi phai chia lai thang chia dp, mdi dp chia tren mat chia dp cua G cd gia tn Idn gap n Iln (100 Ian) gia tri cua mdi dp chia khi khdng mac them s vao G (Gia tn cua mdi
dp chia tren thang do mdi la 1 mA)
2.2.4 De xuat VD can giai quyet tiep
- Cng vdi I s ( R^ nhlt dinh) mac song song vdi G, GHD I cua G chi dflpc md rpng
tdi mot gia tri I xac dinh (n xac dinh) Vay lam thi nao de GHD I cua G dfldc md rdng tdi cac gia tri I khac nhau, nghia la ampe ke cd nhieu thang do?
- Vl du nhfl: Lam thi nao de GHD 1 cua G do I da tim hieu dfldc md rpng tdi hai gia tri I khac nhau (ampe kl se cd hai thang do khac nhau)?
2.2.5 Suy doan va thuc hien giai phap GQVD
- Muon G dupc md rdng GHD tdi cac gia tri I khac nhau thi phai mac song song vdi G cac s cd R^ khac nhau
- Neu muon G do I da lim hieu cd the do dudc hai Imax khac nhau thi mac cac sdn
si va s2 khac nhau song song vdi G theo Hinh 6:
Hinh 6 Ampe ke co 2 thang do
+ Khi dung hai chdt ( - ) va (I): (G ndi tilp RO) // (Rsl ndi tilp Rs2)
+ Khi dflng hai chdt ( - ) va (2): (G noi tilp RQ ndi tilp R s 2 ) / / R s l
Vi RA khi dung hai chot ( - ) va (1) Idn hdn RA khi dung hai chdt ( - ) va (2) nen GHD 11 khi dung hai chdt ( - ) va (1) nhd hdn GHD 12 cua ampe kl khi dung hai chdt ( - )
va (2)
2.2.6 Kiem tra tinh dung dan cua ket luan da rut ra b ampe ke thUc hanh va tim
hieu cac thong so cua nd
- Md mat sau cua ampe kl thflc hanh de xac dinh each mic cac s vdi G va khang
dinh tinh dflng dan cua giai phap da dl x u l t GV bd sung thdng tin ve cac gia tri Rg =^ -'lS^R(i = 3i2.R^i - 0,030 vaR^2 - 0,12ii
- Dfla vao quan sat mat ngoai cua ampe kl (Hinh 7), xac dinh chflc nang (do I mot
Trang 7Hinh 7 Ampe ke thUc hanh
sfl dung cac chdt tren ampe kl, gia ui I cfla mdi dp chia tren tflng thang do va tra Idi eac cau hdi: Khi nao thi I can do cd gia tri dUdng cd gia tri am'^ Bill d p chinh xac cua ampe kl la 2.5, tinh sai sd he thong cfla phep do 1 do ampe ke gay ra flng vdi mdi thang
do (Ampe kl cd hai thang do' khi dung hai chot ( - ) va (0.6A), ampe kl ed thang do
- 0 , 2 A - 0 - 0, 6A, GHD la 0 GA, gia tri cfla mdi dp chia la 0, 02A; cdn khi dung hai
chot ( - ) va (3A) ampe kl co thang do: -\A -0 - 3.1 GHD la 3A gia tri cfla mdi dp
chia la U, lA Vach 0 cua ampe ke khdng d gifla cac thang do Cudng dp 1 cln do se mang gia iri dUdngkhi 1 di vao cac chdi (l),(iA) va (:iA)
2.3 Cac giai doan nghien cu'u nguyen tac cau tao va hoat dong cua von
ke theo con dirbng thiet kc
2.3.1 Nghien cu'u li thuyet va Ihuc nghiem ve dien ke thuc hanh do hieu dien the
dc lam xuat hien VD can giai quyet
(Lam the nao de lam giam anh hudng cua dien kl den gia in hieu dien thi cln do khi mac nd vao hai dau doan mach va md rpng dUde GHD hieu dien the cfla G ?)
- Vi nen ngoai viec dung G do 1, cd the dung G de do U bang each ghi U lfldng Ung vao cac vach tren thang chia dp cua G Neu dflng G do 1 da lim hieu (Ifinh 1) de do U thi
G nay se cd may ihang do U ? Ve cac ihang do nay trong dd cd ghi cac gia tri U lUdng flng thay cho cac gia tri Id cac vach chia tren G doi (Vi Uc;„ - 1R(;-Uc;i ~- IR, -• l(Rc; i Ro)
da bilt R(! va Ri) nen neu dung G do I da tim hicu de do U thi G cd hai ihang do:
+ Khi dung hai chdt ( —) va (GQ) ' -3niii\' - 0 - 3()ni\' Gia in cua mdi dp chia la
l i i i W
+ Khi dung hai chdi (—) va (GI) • -750iiiV - 0 - 750niV Gia tri cua mdi ddchia
la 2r.niV
- Ddi chilu cac thang do da ve vdi cac thang do d mat ngoai cua G do V dc kiem
tra du doan vl cac ihang do (Thang do d mat ngoai cfla G dung nhu thang do da dfl doan)
Trang 8Hinh 8 Dien ki thifc hanh do U
thang do khi sil dung hai chdt ( - ) va (Go), khong ghi ddn vi do (mV)
- DUa vao quan sat mat ngoai cua G do U hay xac dinh them cac thong tin: ChiJc nang (Do U mot chieu), kieu CO cau do (Kieu til dien) cSp chinh xac (sai so he thong ciia phep do U do G gay ra ilng vdi tilng thang do), chiju quay ciia kim chi ling vdi tilng trudng hop
- Nghien ciiu h' thuyet ve anh hudng ciia G den gia tri U can do (Hinh 9): Ap dung dinh luat 6 m ddi vdi loan mach khi chua mac G va khi mac G de thay rang: Viec mac G
do II giOa hai dau doan mach AB lam cho gia tri U' do dUdc sai lech (lam giam) so vdi gia tri thuc cua U can do (Hieu diun the doc duoc tren G khi mac G vao doan raach AB
fRR,
Hinh 9 Do II nhil G
£RR,
R t R + 1 (R + R.)
RR. + \(Y ¥ R,,
R 1
< hieu dien
the khi chua mac G U = R)
R -t- r
- Nghien ciiu thifc nghiem ve anh hudng ciia G den gia In (J can do: Liip mach dien nhil Hinh 10 Dich chuyen bi€n trd de thay ddi UAB t'ng vdi mdi UAB, Ian lUdt doc s6 chi ciia Gi khi chi mac Gi va khi mac dong thdi Gi va G^ vao doan mach AB de thay: So chi ciia G1 khi miic ca G1 va Gy ludn nhd hdnsdchiciiaGi khi chi mac Gj Nhu viiy, vice nghien ciiu li thuyet va thuc nghiem deu din tdi nhan xef Khi mac G vao hai dau doan mach can do II G dii lam giam gia tn U c&n do, gay sai sd ciia phep do
U vii mdi G chi cd mdt GHD Uo xiic dinh
Trang 9U^i^-^Sy
U^
Hinh 10 Kiem nghiem dnh hudng cua G den U cdn do
VD can giai quyet la: Lam the nao de lam giam anh hudng cua G din phep do U (lam giam sai sd cua phep do L') khi mac G vao hai dau doan mach cln do U va cd each nao de cd the sfl dung G do dfldc U cd gia tri Idn hdn UQ, tflc la md rdng dUde GHD cua
G ?
2.3.2 Suy doan va thuc hien giai phap GQVD nhd SLLT tfl cac kien thflc da biet
- Suy doan giai phap GQVD:
-R + Tfl bieu thflc
U
-R + r + -rR
ta Ihay; De lam giam anh hfldng cua G din gia tri U cln do phai lam iang R„ sao cho
Rg > R iJng vdi G da cho (R,; nhlt dmh), cd the mac dien trd phu ndi lilp vdi G trong DCD Nhd dd R DCD se tang len
+ Cung cd the sfl dung giai phap mac dien trd phu noi tilp vdi G irong DCD de chia mdt phln hieu dien thi dat vao hai dau AB cua doan mach, lam cho L\ khdng vudi qua gia tri Ud phln hieu dien thi cdn lai (U - Uo) dfldc dat vad dien ird phu (chia ihl) Nhd
dd DCD cd the do dfldc U > (IQ
- Thflc hien giai phap da suy doan: Ap dung dinh lual Om cho doan mach mac ndi tilp cac dien ird khi mlc dien trd phu ndi tilp vdi G biln nd thanh vdn ke (Hinh 11) cd:
Hinh 11 Cdu tao eiia Von he
+ Rv - RA + Rp' ^hay: R\- > R R\' > R,,; dien trd phu lam iang dien trd cua DCD va do dd, lam sai sd cua phep do U nhd hdn
Trang 10(m : he sd md rdng thang do, >1), thSy: Rp lam tang GHD cua G liun cho vdn ke do duoc
Umax gap m I™ Uii toi da ma G do diroc
+ Mudn GHD U cua C tang len m Ian (m = -~) tU dien trd phu mac noi tiSp vdi
G phiii cd R.p ^ [m - l)Rg
+ Neu Rp cang Idn thi Rv cang Idn, anh hudng ciia DCD ddn gia tri U can do cang
nhd va GHD (m) cua vdn ke cang Idn
2.3.3 Kiem nghiem abb TN tinh diing dan cua kit luan da rilt ra ve viec lam tang
GHD cua G bang each mac Rp noi tiep vdi G
- Dua vao bieu thiic tinh U\- tim do Idn Rp phai mSc noi tiep vdi G do U khi dung hai chdt ( - ) va (G„) de biSn G thanh vdn ki cd GHD U„,,^ la 3V, da biSt khi diing hai
- 1 I R biet Uvmax = 3V, Ujm^ khi diing chdt nay Rj = 100! i? (Vi Rp =
U s hai chot ( - ) va (Go) lii 30niV R, = lOOf! nen Rp = 9900!!)
- Dua vao bieu thiic U, = — , tinh cac gia tri U iing vdi Uvj = IV, Uv2 =
^ m 1 3V,Uv.i = 2VvaUv4 = - I V
Ilinh 12 Kiem nghiem cdc gid tri \]^ dd tinh dUdc
- Thilt kl mach dien va tiln hanh TN de kiem nghiem cac gia trj U^ da tinh dudc
Ifl li thuyet
Lap mach dien nhfl Ifinh 12^ trong dd G dudc dung vdi hai chot ( - ) va (Go) va Rp dfldc tao ra nhd dien trd cd cac vach mau de tiln hanh TN kiem nghiem cac gia tri L'^ da tinh dfldc Cac day ndi phai cd dien trd nhd Kit qua TN cho thay: Cac U^ dpc dfldc tren
G trung vdi eac l'^ da tinh dflpc
- NIU van dung mat chia dd cua G do U lam mat chia dd cua von kl mdi dUdc tao bdi G khi dung hai chdt ( - ) va (Go) va dien trd phu R.,, da mac, xac djnh thang do mdi va gia iri cfla mdi dd chia tren thang do nay (Vi U\' ^ mUp nen sau khi mac Rp ndi tilp vdi
G, nlu van dung mat chia dp cua G dc doc U do dUdc thi phai chia lai thang chia dd, mdi
dd chia iren mat chia dd cfla G cd gia tri Idn gIp m Ian gia tn cfla nd khi khdng mlc R,,