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BAITAP cudi CHirON GI 1.1 C 1.2 D 1.3 Ạ 1.4 Ạ 1.5 D.
1.1. C. 1.2. D. 1.3. Ạ 1.4. Ạ 1.5. D.
1.6. C. 1.7. C. 1.8. D. 1.9. C. 1.10. B.
1.11. a) Mdi difn tich chiu tdc dung cua hai luẹ Mudn hai lue nay can bdng nhau thi ehung phai cd cflng phucmg, ngugc chidu va eung cudng dọ Nhu
vay, ba didm A, fl, C phai ndm tren eung mdt dudng thang.
Difn tfch am qQ phai ndm xen 2q q^ q
gifla hai dien tfch duong va phai ~* © *~*—G)—<-©-»•
- V ' <= r ^ C B
nam gdn dien tfch cd đ ldm q
(ffinhllG).' Hinhl.lG
h)DatBC = xvaAB = ạTac6AC = a-x.
Cudng do cua Itic ma difn tich q tdc dung len qQ la :
Cudng do cua luc ma difn tfch 2q tdc dung len qQ la :
\'2-qqo\
^AC = k- 3
Vdi Fgc = FAC thi ta cd :
_1 _ 2
x^ (a - xf
Giai ra ta duge x = ăy[2 - 1). Vay BC = ăV2 - 1)
BC » 0,414ạ
c) Xet su can bdng cua difn tfch q.
Cudng đ eua liie md difn tfch 2q tac dung len q la :
F -M •
^AB - '^ 2
â
Cudng đ cua Itic ma difn tieh qQ tac dung len q la :
F -^1M1
^CB - l^ ~
"^i ^AB = •^CB nen ta cd ^ - = ^ 2M ^ kol
2 2 a X a X 1 9 «-2,91^0- 1.12. a) F = A ' i = 9.109 2-l>6^-10"^J ^ 33,1.10-^N. r^ 1,18^.10"^° b) Liic difn đng vai trd eua luc hudmg tam.
F .2 4;r2
F = mrci) = mr.——
ji
V F \ -^-^1 in-9 33,1.10" r « 3,55.10-1^ s r « 3,55.10-1^ s
1.13. a) Nhan xet tháy Afl^ = CÂ +CB^. Do đ, tam gidc AflC vudng gde
d C.
Veeto cudng đ difn trudng do q^ gay ra d C cd phuong ndm dgc theo
,-8
* J ? l L , 9.10'HOI = 9.10»
Anl n i r \ - 4
V/m.
AC^ 9.10"
Vectd cudng'đ difn trudng do (?2 gay ra d C cd phuong ndm dgc theo
BC, chidu hudmg vi ^2 vd cudng đ :
E2-kHr = 9 . 1 0 ' ^ ^ = 9.10^ V/m.
flC^ 16.10-^ Vectd cudng đ difn trudng tdng
hgp tai C la :
Fc = Fl + Fj ffinh binh hdnh ma hai canh la hai vecto Fi vd F2 trd thanh mdt
hinh vudng ma EQ ndm dgc theo
dudmg cheo qua C.
vay : Fc = Fi>/2 = 9.>/2.10^ V/m. Fc « 12,7.10^ v/m.
Phuong va chidu cua vecto EQ dugc ve tren ffinh L2G.
b) Hinh 1.20 El D A ?1 Hinh Ị30 B -0 <72
Tai D ta ed Ej^ = Ei + E2 = 0 hay Fj = -F2.
Hai vecto F^ va F2 cd cflng phUdng, ngugc chidu vd cung cudng đ. Vay
didm D phai ndm tren dudng thang Afl vd ngoai doan Afl. Vi 1^2! ^ kl| nen D phai ndm xa (72 hom q^ (ffinh Ị3G).
Dat DA = JC va Afl = a = 5 cm ; ta cd :
Fi = ' ^1 - 7
Vdi Fl = F2 thi : (a + xf \qi\ = x^ ^2!
(a + x)^\ = x^\
(a + x)V9.10-^ = xVl6.I0"^
3(a + x) = 4x
J: = 3a = 15 em.
Ngoai ra, cdn phai kd đn tdt ca cae didm nam rdt xa hai difn tfch q^
va ^2-
1.14. a) Mudn duge tang tdc thi electron phai duge bdn tfl ban am đn ban
duong cua tu difn (ffinh Ị4G).
b) Cdng cua luc difn bdng đ tang đng nang cua electron :
20 ^-20
A = W^-W^^= 40.10"^" - 0 = 40.10"^" J
Mat khdc, ta lai cd A = eU_^
19, A = -1,6.10''" U_+ A = -1,6.10''" U_+ -l,6.10"^^t/_+ = 40.10"^° Ụ = - — = - 2 , 5 V ^ 1,6 0- - + vay (/+_ = 2 , 5 V. d 1.10'^ HinhỊ4G 250 V/m.
1.15. a) Cdng ma ta phai td'n trong su ion hod nguyen tfl hidrd da Idm tang nang
lugng toan phdn eua hf electron va hat nhan hidrd (bao gdm đng nang cua electron vd thd nang tuong tac gifla electron vd hat nhan).
Vi nang lugng todn phdn d xa vd cite bdng khdng nen nang lugng todn phdn cua hf luc ban đu, khi chua bi ion hoa, se ed đ ldn bdng nang lugng ion hod, nhung nguge đu :
W^tp=-^ion=-13,53 eV
b) Nang lugng toan phdn cua hf gdm đng nang eua, electron va thd nang tuong tdc gifla electron va hat nhan :
mv
^p=Ws+w,=-Y- + Wt (1)
The nang W^ cua electron trong difn trudng eua hat nhan cd gia tri am.
Chdc chdn do ldm cua W^ ldm hon đ ldm cua đng nang, nen nang lugng toan phdn cd gia tri am.
Luc difn do hat nhan hut electron đng vai trd luc hudng tam :
I i\ 1
,\e\ mv
k-7r =
r^ r
Ddng nang eua electron la :
H . ^ = . ^ . ^ = 21,78.10-'^ J Thd nang cua electron la : Thd nang cua electron la :
» -21,65.10"^^ - 21,78.10"^^ = -43,43.10"'^ J.
e) Ta cd hf thflc W^ = -V.e hay V = ^ vdi Wt = -43,43.10"^^ J vd - e = -1,6.10"^^ C thi y = 27,14 V. V la difn thd tai mdt didm tren
Chuang II