Tải bản đầy đủ (.doc) (2,862 trang)

Tài liệu ôn tập vật lý 9 rất hay

Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (1.89 MB, 2,862 trang )

��#ࡱ#�################>###�� #############
###8###########:#######����####3###4###5###6###7###�#######�#######~###�###|
###�###�������������������������������������������������������������������������
��������������������������������������������������������������������������������
��������������������������������������������������������������������������������
��������������������������������������������������������������������������������
�������������������������������������������������������������������������#q`
###�#�###############\�####bjbjqPqP##################
###�T###:###:##�[######�###############�
######��##########��##########��##################�#####V#######V###V#######V###
####� ######� ######� ##�###########v!
######z"######z"######z"##�####$##l###n)##�###v!#######n##�###v,##
###�7##@###�7######�7######B9######ࡱ######ࡱ######ࡱ######ek######gk######gk######
gk######gk######gk######gk##$###�q##h###Jt##d###�k##1###################�
######�######################�~##6###��##"###�######�######�k##############V####
###V#######�7##############B9##>E##�m######��######��######��######�##F###V###�#
##�7##l###�
######B9######ek##############��################################################
######�######ek##############��######��##�####G##`###�###�###�
##############################################################CQ######B9######j,
##


###�B�c#��#########z"######@�##�
##ࡱJ##\###########�e##�###�m##0####n######�J##h###�t######��##T
##�t##�###CQ####################################################################
##########�t##############�
######QQ##8###ࡱ######�##�###��######��##�###��##t###############################
####ࡱ######ࡱ######ࡱ######�k######�k######################################J�##^##
#################################ࡱ######ࡱ######ࡱ#######n######�######�######�###
###�##############v!######v!######v!######z"######v!######v!######v!


######z"######v!######v!######v!
######V#######V#######V#######V#######V#######V#######����######


################################################################################
################################################################################
################################################################################
################################################################################
################################################################################
################################################################################
################################################################################
###################�� c��ng �n t�p L� 9Ch��ng I. �i�n h�cKi�n th�c c�n nh�.C��ng
�� d�ng �i�n ch�y qua m�t d�y d�n t� l� thu�n v�i hi�u �i�n th� ��t v�o hai ��u
d�y d�n ��.
# EMBED Equation.3 ###=# EMBED
Equation.3 ###=...= h�ng s� �� th� bi�u di�n s� ph� thu�c c�a c��ng �� d�ng
�i�n v�o hi�u �i�n th� l� m�t ���ng th�ng �i qua g�c to� ��
�i�n tr� c�a d�y d�n l� ��i l��ng ��c tr�ng cho m�c �� c�n tr� d�ng �i�n
c�a d�y d�n nhi�u hay �t.R = # EMBED Equation.3 ### ��nh lu�t �m.C��ng �� d�ng
�i�n ch�y qua d�y d�n t� l� thu�n v�i hi�u �i�n th� ��t v�o hai ��u d�y d�n v�
t� l� ngh�ch v�i �i�n tr� c�a d�y d�n.
I = # EMBED
Equation.3 ###
5. ��nh lu�t �m cho �o�n m�ch m�c n�i ti�p.
I = I1 = I2 =...= In
R1
R2
Rn#
U = U1 + U2 +...+ Un
R = R1 + R2 +...+ Rn

v�:
# EMBED Equation.3 ### =# EMBED Equation.3 ### * N�u c� n �i�n tr�
gi�ng nhau c� gi� tr� R0 m�c n�i ti�p th�:R = nR0
R1#6. ��nh lu�t �m cho �o�n
m�ch m�c song song.
U = U1 = U2
=...= Un
R2 I = I1 + I2 +...+ In
# EMBED Equation.3 ### = # EMBED
Equation.3 ###+ # EMBED Equation.3 ###+...+ # EMBED Equation.3 ###
Rn
v�:
# EMBED Equation.3 ### = # EMBED
Equation.3 ###
*
N�u c� hai �i�n tr� m�c song song th�:
R = # EMBED Equation.3 ###
* N�u c� 3 �i�n tr� m�c song song th�:
R = # EMBED Equation.3 ###
* N�u c� n �i�n tr� b�ng nhau c� gi� tr� R0 m�c song song v�i nhau th�:
R = # EMBED Equation.3 ###
6. �i�n tr� c�a d�y d�n t� l�
thu�n v�i chi�u d�i d�y d�n, v�i �i�n tr� su�t c�a v�t li�u l�m d�y d�n, t� l�
ngh�ch v�i ti�t di�n c�a d�y d�n.
R = (# EMBED Equation.3
###
7. Bi�n tr� l� l� �i�n tr� c� th� thay ��i ���c tr� s� v� s� d�ng ��
�i�u ch�nh c��ng �� d�ng �i�n.
8. S� o�t (W) ghi tr�n m�i d�ng c� �i�n cho
bi�t c�ng su�t ��nh m�c c�a m�i d�ng c� ��. Khi � hai ��u m�t d�ng c� �i�n c�

hi�u �i�n th� b�ng hi�u �i�n th� ��nh m�c th� n� ho�t ��ng b�nh th��ng v� c�ng
su�t ti�u th� b�ng c�ng su�t ��nh m�c.
9. C�ng th�c t�nh c�ng su�t �i�n.
P = UI = I2R = # EMBED Equation.3 ###
10. �i�n
n�ng l� n�ng l��ng c�a d�ng �i�n.
11. C�ng c�a d�ng �i�n s�n ra trong m�t
m�ch �i�n l� s� �o l��ng �i�n n�ng chuy�n ho� th�nh c�c d�ng n�ng l��ng kh�c.
A = P.t = UIt
* M�i s� ��m c�a c�ng t�
�i�n cho bi�t l��ng �i�n n�ng �� s� d�ng trong 1 gi�.
1
s� = 1kWh = 3 600 000 J
12. ��nh lu�t Jun-Len x�.
Q =
I2Rt
*
1 Jun = 0.24 calo
1 calo = 4.18 Jun* V� d�:Khi
�a�t va�o hai �a�u da�y da�n mo�t hie�u �ie�n the� 12 V th� c���ng �o� do�ng
�ie�n cha�y qua da�y da�n la� 0,5A. Ne�u hie�u �ie�n the� �a�t va�o hai �a�u
da�y da�n �o� ta�ng le�n �e�n 36V th� c � d � cha�y qua no� la� bao nhie�u?
HD:
V� c � d � cha�y qua da�y da�n t� le� thua�n v��i hie�u �ie�n the� �a�t va�o hai
�a�u da�y da�n �o� ne�n:V��i U1 = 12V th� I1 = 0,5AV��i U2 = 36V th� I2 =# EMBED
Equation.3 ###Do�ng �ie�n cha�y qua mo�t da�y da�n co� c���ng �o� la� 6mA khi
no� ����c ma�c va�o h� t 12V. Muo�n do�ng �ie�n cha�y qua da�y da�n �o� co�
c���ng �o� gia�m �i 4mA th� hie�u �ie�n the� la� bao nhie�u?
HD: Do�ng �ie�n co�
c���ng �o� gia�m �i 4 mA t��c la� I = 2mA . C���ng �o� do�ng �ie�n gia�m �i 3

la�n=> U gia�m �i 3 la�n khi �o� U2 = 4VCho �ie�n tr�� R= 15# EMBED Equation.3
###Khi ma�c �ie�n tr�� na�y va�o hie�u �ie�n the� 6V th� do�ng �ie�n cha�y qua
no� co� c���ng �o� ba�ng bao nhie�u?
Muo�n c���ng �o� do�ng �ie�n cha�y qua �ie�n
tr�� ta�ng the�m 0,3A so v��i tr���ng h��p tre�n th� hie�u �ie�n the� �a�t va�o
hai �a�u �ie�n tr�� �o� la� bao nhie�uHD: a)I= # EMBED Equation.3 ###
b) U� = RI�= 15* 0,7 = 10,5V
( I� = 0,4+0,3=0,7A)4. Co� hai bo�ng �e�n ghi
110V-75W va� 110V-25W.
So sa�nh �ie�n tr�� cu�a hai bo�ng �e�n tre�n?
HD: T�nh �ie�n tr�� cu�a mo�i bo�ng �e�n ro�i so sa�nh5. Mo�t da�y da�n


����c ma�c va�o hie�u �ie�n the� 6V th� c���ng �o� do�ng �ie�n cha�y qua no� la�
0,3A. Mo�t ba�n ho�c sinh no�i ra�ng: Ne�u gia�m hie�u �ie�n the� �a�t va�o hai
�a�u da�y da�n �i 2V th� c���ng �o� do�ng �ie�n cha�y qua da�y da�n khi �o� co�
c���ng �o� la� 0,15 A. Theo em ke�t qua� na�y la� �u�ng hay sai?
V� sao?
HD: Khi
hie�u �ie�n the� gia�m �i 2V t��c la� U2 = 6-2=4V
C���ng �o� do�ng �ie�n
khi �o� la� I2 = I1.U2/U1 = 0,3.4/6 = 0,2AVa�y ke�t qua� �� �a�y la� sai ba�n
�a� nha�m la� hie�u �ie�n the� gia�m �i 2 V ch�� kho�ng pha�i hie�u �ie�n the�
gia�m �i hai la�n6. La�m th� nghie�m kha�o sa�t s�� phu� thuo�c cu�a c���ng �o�
do�ng �ie�n va�o hie�u �ie�n the� �a�t gi��a hai �a�u va�t da�n ba�ng kim loa�i,
ng���i ta thu ����c ba�ng so� lie�u sau:
U(v)#0#1,5#3,0#4,5#6,0#7,5#9,0##I(A)#0#0,31#0,61#0,90#0,129#0,149#0,178##R(#
EMBED Equation.3 ###)#########Ve� �o� th� bie�u die�n s�� phu� thuo�c I va�o U
Ne�u bo� qua nh��ng sai so� trong phe�p �o th� �ie�n tr�� cu�a va�t da�n �o�
ba�ng bao nhie�u?

HD: a.#b) �ie�n tr�� cu�a da�y da�n:R=# EMBED Equation.3 ####
EMBED Equation.3 ###8. Mo�t �oa�n ma�ch go�m ba �ie�n tr�� R1 = 3# EMBED
Equation.3 ###; R2 = 5# EMBED Equation.3 ###; R3 = 7# EMBED Equation.3 ###
����c ma�c no�i tie�p v��i nhau. Hie�u �ie�n the� gi��a hai �a�u �oa�n ma�ch la�
U = 6V.1/ T�nh �ie�n tr�� t��ng ���ng cu�a �oa�n ma�ch.2/ T�nh hie�u �ie�n the�
gi��a hai �a�u mo�i �ie�n tr��.H���ng da�n1/ �ie�n tr�� t��ng ���ng cu�a ma�ch:#
EMBED Equation.3 ### = 3 + 5 + 7 = 15# EMBED Equation.3 ###2/ C���ng �o� do�ng
�ie�n trong ma�ch ch�nh
# EMBED Equation.3 ###Ma� ma�c
no�i tie�p ne�n I ba�ng nhau. Ne�u ta co� hie�u �ie�n the� hai �a�u mo�i �ie�n
tr�� la�:# EMBED Equation.3 #### EMBED Equation.3 #### EMBED Equation.3 ###9.
Cho ba �ie�n tr�� R1 = 6# EMBED Equation.3 ###; R2 = 12# EMBED Equation.3 ###;
R3 = 16# EMBED Equation.3 ### ����c ma�c song song v��i nhau va�o hie�u �ie�n
the� U = 2,4V1/ T�nh �ie�n tr�� t��ng ���ng cu�a �oa�n ma�ch.2/ T�nh c���ng �o�
do�ng �ie�n qua ma�ch ch�nh va� qua t��ng �ie�n tr��.H���ng da�n1/ �ie�n tr��
t��ng ���ng cu�a ma�ch:# EMBED Equation.3 #### EMBED Equation.3 ###2/ C���ng
�o� do�ng �ie�n qua ma�ch ch�nh:# EMBED Equation.3 ###V� ma�c song ne�n U ba�ng
nhau. Ne�n c���ng �o� do�ng �ie�n qua t��ng �ie�n tr�� la�:# EMBED Equation.3
#### EMBED Equation.3 #### EMBED Equation.3 ###b�i t�p* �o�n m�ch n�i ti�pC�u
1.Cho 2
################################################################################
################################################################################
###########################i#�#n# #t#r#�# #R#1# #v#�# #R#2# #m#�#c# #n#�#i#
#t#i#�#p#,# #h#i#�#u# ###i#�#n# #t#h#�# #U# #k#o# ###�#i# #.#C#h#�#n#g#
#m#i#n#h# #r#�#n#g# #h#i#�#u# ###i#�#n# #t#h#�# #g#i#�#a# #2# ###�#u# #m#�#i#
###i#�#n# #t#r#�# #t#�# #l#�# #t#h#u#�#n# #v#�#i# ###i#�#n# #t#r#�# ###�#.##
#H#D#:# ###o#�#n# #m#�#c#h# #n#�#i# #t#i#�#p# #t#h#�# #:# #I#1#=# #I#2#
#=#># #U#1#:# #R#1#=# #U#2#:# #R#2# #=#># #U#1#:# #U#2# #=# #R#1#:#R#2##C#�#u#
#2#.#H#a#i# ###i#�#n# #t#r#�# #R#1#,#R#2# #m#�#c# #n#�#i# #t#i#�#p#.#B#i#�#t#
#R#1# #=# #3#�#,# #R#2# #=# #6#�#,# #U#A#B# #=# #1#2#V#.#T#�#m#:##a#.###i#�#n#

#t#r#�# #t#�#�#n#g# ###�#�#n#g# #c#�#a# ###o#�#n# #m#�#c#h##b#.#C#�#�#n#g# ###�#
#d#�#n#g# ###i#�#n# #q#u#a# #m#�#i# ###i#�#n# #t#r#�##c#.#H#i#�#u# ###i#�#n#
#t#h#�# #2# ###�#u# #m#�#i# ###i#�#n# #t#r#�## #H#D#:# #a#.###i#�#n# #t#r#�#
#t#�#�#n#g# ###�#�#n#g# #R#t### #=# #R#1#+#R#2# #=# #3#+#6# #=# #9#�#
#b#.#C#�#�#n#g# ###�# #d#�#n#g# ###i#�#n# ##I# #=# #U#/#R#t### #=# #1#2#/#9# #=#
#4#/#3#A##V#�# #R#1# #n#t# #R#2# #s#u#y# #r#a# #I#1# #=# #I#2# #=# #I# #=#
#4#/#3#A##c#.##U#1# #=# #I#1#.#R#1# #=# #4#/#3#.# #3#=# #4#V# ##U#2# #=#
#I#2#.#R#2# # #=# #4#/#3#.#6# #=# #8#V##C#�#u# #3#.#C#h#o# #R#1#,#R#2#,#R#3#
#m#�#c# #n#�#i# #t#i#�#p#,# #b#i#�#t#:#R#1#=# #1#�#,# #R#2# #=# #2#,# #R#3# #=#
#2#�#;# #U#A#B# #=# #1#6#V#.#T#�#m#:##a#.###i#�#n# #t#r#�# #t#�#�#n#g#
###�#�#n#g# #c#�#a# ###o#�#n# #m#�#c#h##b#.# #H#i#�#u# ###i#�#n# #t#h#�# #h#a#i#
###�#u# #m#�#i# ###i#�#n# #t#r#�## #H#D#:##a#.###i#�#n# #t#r#�# #t#�#�#n#g#
###�#�#n#g#:# #R#t### #=# #R#1#+#R#2#+#R#3# #=# #1#+#2#+#1# #=# #4#�#
#b#.#I#=#U#/#R#t###=#1#6#/#4#=#4#A##U#1#,#U#2#,#U#3#=#?
##" T#h#e#o# ###�#n#h#
#l#u#�#t# #�#m#:# #I# #=# #U#/#R#t### #=# #1#6#/#4#=#4# #A##" R#1# #n#t# #R#2#
#n#t# #R#3# #n#�#n#:# #I#1#=# #I#2#=# #I#3#=# #I#=# #4#A##" U#1# #=# #I#1#.#R#1#
#=# #4#.#1# #=# #4#V##" U#2# #=# #I#2#.#R#2# #=# #4#.#2# #=# #8#V##" U#3# #=#
#I#3#.#R#3# #=# #4#.#1# #=# #4#V##C#�#u# #4#.# #C#h#o# #R#1# #=# #1#�#,# #R#2#
#=# #2#�#,# #R#3# #=# #3#�# #m#�#c# #n#�#i# #t#i#�#p# #n#h#a#u#,# #I# #=#
#0#,#5#A# #.#T#�#m#:##a#.#H#i#�#u# ###i#�#n# #t#h#�# #c#�#a# #m#�#c#h# #


#b#.#T#�#n#h# #U#2#3# # ##
#H#D#:# #a#.#U#A#B# #=# #?
####i#�#n# #t#r#�#
#t#�#�#n#g# ###�#�#n#g#:# #R#t### #=# #R#1#+#R#2#+#R#3# #=# #6#�##D#o# #m#�#c#
#n#�#i# #t#i#�#p#:# #I#1# #=# #I#2# #=# #I#3# #=# #I# #=# #0#,#5#A##H#i#�#u#
###i#�#n# #t#h#�#:# #U#A#B# #=# #I#.#R#t### #=# #0#,#5#.#6# #=# #3#V#
#b#.#U#2#3#=#I#.#R#2#3##V#�#i#:# #I#2# #=# #I#3# #=# #I#2#3# #=# #0#,#5#A## # #

# # # # # #R#2#3# #=# #R#2#+#R#3# #=# #5#�##S#u#y# #r#a# #:# #U#2#3# #=#
#0#,#5#.#5# #=# #2#,#5#V##C#�#u# #5#.# #C#h#o# #2# ###i#�#n# #t#r#�#
#R#1#=#R#2#=#1#0#�# #m#�#c# #n#�#i# #t#i#�#p# #.# ##a#.#T#�#m# ###i#�#n#
#t#r#�# #t#�#�#n#g# ###�#�#n#g# #c#�#a# #m#�#c#h# #.##b#.#M#�#c# #t#h#�#m#
###i#�#n# #t#r#�# #R#3#=#5#�# #n#�#i# #t#i#�#p# #v#�#i# #R#1#.# #T#�#m#
###i#�#n# #t#r#�# #t#�#�#n#g# ###�#�#n#g# #c#�#a# #m#�#c#h##
#H#D#:#
#a#.###i#�#n# #t#r#�# #t#�#�#n#g# ###�#�#n#g# #R#1# #n#t# #R#2#:# #R#t### #=#
#R#1#+#R#2# #=# #1#0#+#1#0# #=# #2#0#�##b#.###i#�#n# #t#r#�# #t#�#�#n#g#
###�#�#n#g# #(#R#1# #n#t# #R#2#)# #n#t# #R#3#:# #R#t### #=# #R#1#+#R#2#+#R#3#
#=# #2#0#+#5# #=# #2#5#�# ##C#�#u# #6#.# #C#h#o# #R#1# #=# #4#�# #v#�# #R#2#
#m#�#c# #n#�#i# #t#i#�#p# #n#h#a#u#.# #H#i#�#u# ###i#�#n# #t#h#�# #2# ###�#u#
#m#�#c#h# #l#�# #1#2#V# #t#h#�# #c#�#�#n#g# ###�# #d#�#n#g# ###i#�#n# #q#u#a#
#m#�#c#h# #l#�# #0#,#5#A# #.# ###i#�#n# #t#r#�# #R#2# #b#a#o# #n#h#i#�#u#?
##
#H#D#:# #R#2# #=# #2#0#�##C#�#u# #7#.# #C#h#o# #R#2#=#1#0#�# #m#�#c#
#n#�#i# #t#i#�#p# #R#1# #h#i#�#u# ###i#�#n# #t#h#�# #U# #=# #9#V#,# #U#2# #=#
#5#V# #.# #T#�#n#h# #R#1#.##H#D#:# #" I#2# #=# #U#2#/#R#2# #=# #5#/#1#0# #=#
#0#,#5#A##" D#o# #m#�#c# #n#�#i# #t#i#�#p#:# #I#1#=# #I#2# #=# #I# #=# #0#,#5#A#
#" I# #=# #U#A#B#/#R#t### #=#># #R#t### #=# #U#A#B#/#I# #=# #9#/#0#,#5# #=#
#1#8#�##" R#t### #=# #R#1#+#R#2# #=#># #R#1# #=# #R#t###-#R#2# #=# #1#8# #-#1#0#
#=# #8#�##*# #�#O#�#N# #M#�#C#H# #S#O#N#G# #S#O#N#G##C#�#u# #1#.# #C#h#o#
###o#�#n# #m#�#c#h# #R#1#/#/#R#2#.# #C#h#�#n#g# #t#�# #r#�#n#g# #c#�#�#n#g#
###�# #d#�#n#g# ###i#�#n# #c#h#�#y# #q#u#a# #m#�#i# ###i#�#n# #t#r#�# #t#h#�#a#
#m#�#n# #h#�# #t#h#�#c# #I#1#/#I#2# #=# #R#2#/#R#1#.##
#H#D#:# #C#h#�#n#g#
#m#i#n#h#:# #I#1#/#I#2# #=# #R#2#/#R#1##" D#o# #m#�#c# #s#o#n#g# #s#o#n#g# #:#
#U#1# #=#U#2# #<#=#># #I#1#R#1# #=# #I#2#R#2# #<#=#># #I#1#/#I#2# #=#
#R#2#/#R#1##C#�#u# #2#.# #P#h#�#n#g# #h#�#c# #c#�#n# #s#�# #d#�#n#g# #1# ###�#n#
#d#�#y# #t#�#c# #v#�# #1# #q#u#�#t# #t#r#�#n# #c#�# #c#�#n#g# #h#i#�#u#

###i#�#n# #t#h#�# ###�#n#h# #m#�#c# #l#�# #2#2#0#V# #.# #H#i#�#u# ###i#�#n#
#t#h#�# #n#g#u#�#n# #2#2#0#V#.# #M#�#i# #d#�#n#g# #c#�# #c#�# #c#�#n#g# #t#�#c#
#v#�# #c#�#u# #t#r#�# #b#�#o# #v#�# #r#i#�#n#g# #.##a#.#P#h#�#i# #m#�#c# #c#�#c#
#d#�#n#g# #c#�# ###�# #n#h#�# #t#h#�# #n#�#o# ###�# #c#h#�#n#g# #h#o#�#t#
###�#n#g# #b#�#n#h# #t#h#�#�#n#g# ##b#.#V#�# #s#�# ###�# #m#�#c#h# ###i#�#n#
#k#h#i# ###�##
#H#D#:# ##a#.###�#n# #v#�# #q#u#�#t# #p#h#�#i# #m#�#c#
#s#o#n#g# #s#o#n#g# #v#�#o# #n#g#u#�#n# #2#2#0#V# ##b#.#V#�# #s#�# ###�##C#�#u#
#3#.# #C#h#o# #R#1#=#3#�#,# #R#2#=#6#�# #m#�#c# #s#o#n#g# #s#o#n#g# #v#�#i#
#n#h#a#u# #.##a#.#T#�#n#h# #R#t### #.##b#.#M#�#c# #t#h#�#m# #R#3#=#2#�#.#
#S#o#n#g# #s#o#n#g# #v#�#i# #R#2#.# #T#�#n#h# #R#t####
#H#D#:# ##a#.#R#1#
#/#/# #R#2# #<#=#># #1#/#R#t### #=# #1#/#R#1# #+# #1#/#R#2# #=# #1#/#3# #+#
#1#/#6# #=# #1#/#2# #=#>#R#t### #=# #2#�##b#.# #R#1# #/#/# #R#2# #/#/#
#R#3###1#/#R#t### #=# #1#/#R#1# #+# #1#/#R#2# #+# #1#/#R#3# #=# #1#/#3# #+#
#1#/#6# #+# #1#/#2# #=# #1# #=#># #R#t### #=# #1#�##C#�#u# #4#.# #C#h#o#
#R#1#=#3#�#,# #R#2# #=# #R#3# #=# #6#�# #m#�#c# #s#o#n#g# #s#o#n#g# #v#�#i#
#n#h#a#u#,# #U#=#6#V#.##a#.#T#�#m# #R#t### #c#�#a# #m#�#c#h# #.##b#.#T#�#n#h#
#c#�#�#n#g# ###�# #d#�#n#g# ###i#�#n# #t#r#o#n#g# #m#�#c#h##
#H#D#:#
#a#.###i#�#n# #t#r#�# #t#�#�#n#g# ###�#�#n#g# #:# #1#/#R#t### #=# #1#/#R#1# #+#
#1#/#R#2# #+# #1#/#R#3# #=# #1#/#3# #+# #1#/#6# #+# #1#/#6# #=# #2#/#3# ##R#t###
#=# #1#,#5#�##b#.#I# #=# #U#/#R#t### #=# #6#/#1#,#5# #=# #4#A##C#�#u# #5#.#
#C#h#o# #m#�#c#h# ###i#�#n# #c#�# #R#1#=#3#�#,# #R#2#=#6#�# #m#�#c# #s#o#n#g#
#s#o#n#g# #v#�#i# #n#h#a#u#,# #I#1#=#0#,#5#A#.# #T#�#m#:##a#.#R#t### #c#�#a#
#m#�#c#h# ##b#.#T#�#n#h# #h#i#�#u# ###i#�#n# #t#h#�# #c#�#a# #m#�#c#h# #.#
#c#.#T#�#n#h# #c#�#�#n#g# ###�# #d#�#n#g# ###i#�#n# #t#r#o#n#g# #m#�#c#h# #v#�#
#c#�#�#n#g# ###�# #d#�#n#g# ###i#�#n# #q#u#a# ###i#�#n# #t#r#�# #R#2#.##
#H#D#:# #a#.###i#�#n# #t#r#�# #t#�#�#n#g# ###�#�#n#g# #:# #1#/#R#t### #=#
#1#/#R#1# #+# #1#/#R#2# #=# #1#/#3# #+# #1#/#6# #=# #1#/#2# #=#># #R#t### #=#

#2#�##b#.#" U#1# #=# #I#1#.#R#1# #=# #0#,#5#.#3# #=# #1#,#5#V# ## # # #" D#o#
#R#1# #/#/# #R#2# #=#># #U#1# #=# #U#2# #=# #U# #=# #1#,#5#V##C#�#u# #6#.#
#C#h#o# #R#1#=#6#�# #m#�#c# #s#o#n#g# #s#o#n#g# #v#�#i# #R#2#,# #I#1#=#0#,#5#A#


#,# #I# #=# #1#,#5#A#.# #T#�#m#:##a#.#C#�#�#n#g# ###�# #d#�#n#g# ###i#�#n#
#q#u#a# ###i#�#n# #t#r#�# #R#2# #.##b#.#H#i#�#u# ###i#�#n# #t#h#�# #c#�#a#
#m#�#c#h# #.##c#.###i#�#n# #t#r#�# #R#2#.##
#H#D#:# #a#.#T#a# #c#�# #:# #I#
#=# #I#1# #+# #I#2# #=#># #I#2# #=# #I# ## #I#1# #=# #1#,#5# ## #0#,#5# #=#
#1#A##b#.#" D#o# #R#1# #/#/# #R#2# #n#�#n# #:# #U#1# #=# #U#2# #=# #U# #=# #3#V#
#c#.###i#�#n# #t#r#�# #R#2# #:# ##I#2# #=# #U#2#/#R#2# #=#># #R#2# #=#
#U#2#/#I#2# #=# #3#/#0#,#5#=#6#�##C#�#u# #7#.# #C#h#o# #R#1# #=# #2#R#2# #m#�#c#
#s#o#n#g# #s#o#n#g# #v#�#i# #n#h#a#u# #,# #I# #=# #1#,#5#A# #,# #U# #=#1#2#V#.#
#T#�#m#:##a#.#R#t### #c#�#a# #m#�#c#h# #.##b#.###i#�#n# #t#r#�# #R#1#,# #R#2#.#
#c#.#C#�#�#n#g# ###�# #d#�#n#g# ###i#�#n# #q#u#a# #m#�#i# ###i#�#n# #t#r#�# #.##
#H#D#:# #a#.###i#�#n# #t#r#�# #t#�#�#n#g# ###�#�#n#g# #:# #R#t### #=#
#U#/#I# #=# #1#2#/#1#,#5# #=# #8# #�##b#.#R#1# #,# #R#2# #=# #?
##T#a# #c#�# #:#
#1#/#R#t### #=# #1#/#R#1# #+# #1#/#R#2# # # # # # # # # #(#1#)## # #M#�#:# # #
#R#1# #=# #2#R#2# # # # # # # # # # # # # # # # # # # # # # # # # # # #(#2#)#
#v#�# #(#2#)# #=#># #1#/#R#t### #=# #1#/#2#R#2# #+# #1#/#R#2# #=# #3#/#2#R#2#
#=#>#R#2# #=# #3#/#2#.#R#t### #=# #3#/#2#.#8# #=# #1#2#�##(#2#)# #=#># #R#1# #=#
#2#R#2# #=# #2#.#1#2# #=# #2#4#�##c#.#I#1# #,# #I#2# #=#?
##T#a# #c#�# #:# #U#1#
#=# #U#2# #=# #U# #=# #1#2#V##" I#1# #=# #U#1#/#R#1# #=# #1#2#/#2#4# #=#
#0#,#5#A##" I#2# #=# #U#2#/#R#2# #=# #1#2#/#1#2# #=# #1#A##C#�#u# #8#.# #C#h#o#
#2# ###i#�#n# #t#r#�# #R#1#,# #R#2# #m#�#c# #s#o#n#g# #s#o#n#g# #,# #U# #=#
#1#2#V# #;# #I#1# #=# #0#,#5#A# #;# #I# #=# #1#A#.##a#.#V#�# #s#�# ###�#
#m#�#c#h# ###i#�#n#.##b#.#T#�#m# #R#1# #,# #R#2# ## #H#D#:# #a#.#S#�# ###�#

#m#�#c#h# ###i#�#n# #:##b#.# #R#1# #,# #R#2# #=# #?
##" D#o# #m#�#c# #s#o#n#g#
#s#o#n#g# #:# #U#1# #=# #U#2# #=# #U# #=# #1#2#V##" R#1# #=# #U#1#/#I#1# #=#
#1#2#/#0#,#5# #=# #2#4#�##" I# #=# #I#1# #+# #I#2# ##=#># #I#2# #=# #I# ##
#I#1# #=# #1# ## #0#,#5# #=# #0#,#5#A##=#># #R#2# #=# #U#2#/#I#2# #=#
#1#2#/#0#,#5# #=# #2#4#�###C#�#u# #9#.# #C#h#o# #3# ###i#�#n# #t#r#�# #R#1#,#
#R#2#,# #R#3# #m#�#c# #s#o#n#g# #s#o#n#g# #v#�#i# #n#h#a#u#.#B#i#�#t# #I#1# #=#
#2#I#2# #;# #I#3#=#3#I#2# #;# ###i#�#n# #t#r#�# #R#1# #=# #3#�#.# ##a#.#T#�#m#
#R#2#,# #R#3#.##b#.#K#h#i# #h#i#�#u# ###i#�#n# #t#h#�# #2# ###�#u# #m#�#c#h#
#l#�# #6#V# #t#h#�# #c#�#�#n#g# ###�# #t#r#o#n#g# #m#�#c#h# #l#�# #b#a#o#
#n#h#i#�#u# #?
## #H#D#:# #a#.#R#2# #,# #R#3# #=# #?
##" D#o# #m#�#c# #s#o#n#g#
#s#o#n#g# #:# #U#1# #=# #U#2# #=# #U#3# #=# #U##I#1# #=# #U#/#R#1##I#2# #=#
#U#/#R#2##=#># #I#1#/#I#2# #=# #R#2#/#R#1##M#�# #:# #I#1# #=# #2#I#2# ##=#># #2#
#=# #R#2#/#R#1# #=#># #R#2# #=# #2#R#1# #=# #6#�##" I#3# #=# #U#/#R#3##"
I#2#/#I#3# #=# #R#3#/#R#2# #<#=#># #I#2#/#3#I#2# #=# #R#3#/#R#2# #=#># #R#3# #=#
#R#2#/#3# #=# #6#/#3# #=# #2#�##b#.#U#A#B# #=# #6#V##" I#1# #=# #U#1#/#R#1# #=#
#6#/#3# #=# #2#A##" I#2# #=# #U#2#/#R#2# #=# #6#/#6# #=# #1#A# ##" I#3# #=#
#U#3#/#R#3# #=# #6#/#2# #=# #3#A###*# #�#O#�#N# #M#�#C#H# #H#�#N# #H#�#P#
#####B#a#�#i# #1#:# #C#h#o# #m#a#�#c#h# #�#i#e#�#n# #n#h#�# #h#�#n#h# #v#e#�#:##
####H#�#�#�#n#g# #d#a#�#n##1#/# #�#i#e#�#n# #t#r#�#�# #t#�#�#n#g# #�#�#�#n#g#
#c#u#�#a# #R#2# #v#a#�# #R#3#:#### #E#M#B#E#D# #E#q#u#a#t#i#o#n#.#3# # #######
#�#i#e#�#n# #t#r#�#�# #t#�#�#n#g# #�#�#�#n#g# #cu�a ma�ch:# EMBED Equation.3
### 6 = 36# EMBED Equation.3 ###2/ C���ng �o� do�ng �ie�n qua ma�ch ch�nh:#
EMBED Equation.3 ###Ma�: # EMBED Equation.3 ###Ta co�: # EMBED Equation.3 ###
V� R2 // R3 ne�n U2 = U3 = U2,3. Ta co�:# EMBED Equation.3 ####


##Ba�i 2: Cho ma�ch �ie�n nh� h�nh ve�:H���ng da�n1/ �ie�n tr�� t��ng ���ng cu�a

R2 va� R3 la�:# EMBED Equation.3 ###
�ie�n tr�� t��ng
���ng cu�a ma�ch:
# EMBED Equation.3 ###
2/
Hie�u �ie�n the� cu�a ma�ch:# EMBED Equation.3 ###3/ Ta co�: # EMBED Equation.3
### = 6V. Ne�n ta co�:
# EMBED Equation.3 ###
# EMBED
Equation.3 ###B�i t�p �p d�ng ��nh lu�t �m cho �o�n m�ch m�c n�i ti�p, song
song v� h�n h�p.1. Khi ��t v�o hai ��u d�y d�n m�t hi�u �i�n th� l� 18V th�
c��ng �� d�ng �i�n ch�y qua n� l� 0.9A. N�u hi�u �i�n th� t�ng th�m 6V th� c��ng
�� d�ng �i�n c� gi� tr� bao nhi�u?
2. C� 3 �i�n tr� nh� nhau ���c m�c v�i nhau,
m�i c�i c� �i�n tr� R. C� th� m�c ch�ng theo bao
nhi�u c�ch kh�c nhau ��
t�o th�nh m�t �o�n m�ch ?
T�nh �i�n tr� c�a t�ng �o�n m�ch ��?
3. M�t m�ch �i�n
���c m�c nh� h�nh v�. Trong �� R1 = 35 (, R2 = 60 (.
Ampe k� A1
ch� 2.4A.#T�nh c��ng �� d�ng �i�n ch�y qua R2 ?
R1
S� ch� c�a V�n k� l� bao nhi�u?
S� ch� c�a Ampe k� A
l� bao nhi�u?
R24. Ba �i�n tr� R1 = 24
(; R2 = 6 (; R3 = 8 ( ���c m�c
th�nh m�t �o�n m�ch song song. C��ng ��
d�ng �i�n ch�y qua

m�ch ch�nh l� 4A. T�nh �i�n tr� t��ng ���ng c�a �o�n
m�ch?
T�nh c��ng �� d�ng �i�n ch�y qua m�i �o�n m�ch r�?
#5. Cho m�ch �i�n nh�
h�nh v�. Cho bi�t: UAB = 70V; r1 =15 ( ; R2 = 30 (; R3 = 60 (
A
R1
C
B
a) T�nh �i�n tr� t��ng ���ng c�a to�n
m�ch �i�n ?
b) T�nh c��ng �� d�ng �i�n qua c�c �i�n ?
6. C� ba �i�n
tr� R1 = 4 (; R2 = 8 (; R3 = 24 ( ���c m�c v�o hai �i�m A, B c� hi�u �i�n th�
12V. T�nh �i�n tr� t��ng ���ng c�a �o�n m�ch?
R1
r2 #T�nh c��ng �� d�ng �i�n qua m�i �i�n tr� ?
A
B
c)
T�nh hi�u �i�n th� gi�a hai ��u �i�n
R3tr� R1 v� R2?
#7. C� 4 �i�n tr� c� gi� tr� R. N�u c�c c�ch m�c c�c �i�n tr� �� th�nh m�t m�ch
�i�n ?
T�nh �i�n tr� t��ng ���ng c�a m�i �o�n m�ch �� ?
##8. Cho m�ch �i�n nh�
h�nh v�. Trong ��:
##
R1 = R2 = 4( ;
R3 = 6( ; ##

R4 = 5( ; r5 = R6 = 10( ;
T�nh �i�n tr�
t��ng ���ng to�n m�ch ?
##9. Cho m�ch �i�n nh� h�nh v�. Trong �� R1 = 45 (
# Ampe k� A1 ch� 1.2A, Ampe k� a ch� 2.8A #T�nh hi�u �i�n th� UAB c�a �o�n m�ch?
#T�nh �i�n tr� R2?
( 54V; 33.75( )10. Cho m�ch �i�n nh� h�nh v�.
Bi�t R1 = 20( , s� ch� c�a c�c Ampe k� A v� A2# l�n l��t l� 4A v�
2,2A.
###
a)
X�c ��nh hi�u �i�n th� gi�a hai ��u �o�n m�ch#
v�
gi� tr� �i�n tr� R2 ?
#
b)
Gi� nguy�n hi�u �i�n th� gi�a hai ��u �o�n
m�ch,
#
thay R1 b�ng �i�n tr� R3 th�
th�y ampe k� A
ch� 5,2A. S� ch� c�a ampe k� A2 khi �� l� bao
nhi�u ?
T�nh �i�n tr� R3.
( 36V; 16.36( ; 2.2A ; 12( )#11.
M�c hai �i�n tr� R1, R2 v�o hai �i�m A, B c� hi�u �i�n th� 90V. N�u m�c R1 v� R2
n�i ti�p th� d�ng �i�n c�a m�ch l� 1A.N�u m�c R1 v� R2 song song th� d�ng �i�n
qua m�ch ch�nh l� 4,5A. H�y x�c ��nh �i�n tr� R1 v� R2 ?
###
( 30( v� 60( )##########12. Cho m�ch �i�n nh� h�nh v�. Bi�t v�n k�

M
N#########
ch� 84V, ampe k� A ch� 4,2A, �i�n tr�##
R1 = 52,5( .###
T�m
s� ch� c�a c�c ampe k� A1 , A2
v� t�nh �i�n tr� R2.
( 1.6A;
2.6A; 32.3( )
#13. Cho m�ch �i�n nh� h�nh v�. #####
Hi�u �i�n th� gi�a hai
��u �o�n m�ch UMN = 60V.#######
Bi�t R1 = 3R2 v� R3 =8( . s� ch� c�a ###
Ampe k� A l� 4A. T�nh c��ng �� d�ng �i�n qua##
c�c �i�n tr� R1 v�
R2 v� gi� tr� c�c �i�n tr� R1 v� R2.
####
( 1A; 3A; 28( ;28/3( )###14. Cho m�ch �i�n nh� h�nh v�. Trong �� R1= 4( ,#
R2 = 10( , R3 = 15(, hi�u �i�n th� UCB = 5,4V.
T�nh �i�n tr� t��ng ���ng RAB
c�a �o�n m�ch.#T�nh c��ng �� d�ng �i�n qua m�i �i�n tr� v�
s� ch� c�a ampe k�
A.
( 10( ; 0.9A; 0.54A; 0.36A)15. Cho m�ch �i�n nh� h�nh v�. Bi�t R1 = 4( ,
R2 = 6( , R3 = 15( . Hi�u �i�n th� gi�a hai ��u#
�o�n m�ch UAB =
36V. R1
R2#T�nh �i�n tr� t��ng ���ng c�a �o�n m�ch.#T�m s� ch� c�a Ampe
k� A v� t�nh
R3

hi�u �i�n th� hai ��u c�c �i�n tr� R1, R2.
( 6(; 6A; 3.6A;


14.4V; 21.6V)16. Cho m�ch �i�n nh� h�nh v�.
A
B
Bi�t R1 =12( , R2 = 18( , R3 = 20( ,#
Rx c� th�
thay ��i ���c. Hi�u �i�n th� gi�a hai
R1
R2 #
��u �o�n m�ch UAB = 45V.##
a)
Cho Rx = 25(. T�nh
�i�n tr� t��ng ���ng
A
B
c�a m�ch v� c��ng �� d�ng �i�n trong m�ch ch�nh.
b)
��nh gi� tr� Rx �� cho c��ng �� d�ng �i�n qua Rx
nh� h�n
hai l�n c��ng �� d�ng �i�n qua �i�n tr� R1.
( 18(; 2.5A; 40( )17. Cho m�ch
�i�n nh� h�nh v�.
R2
D
R3
##Trong ��: R1 = 15( ; R2 = 3 ( ; R3 = 7( ; R4 =
10 (.

A
R1 C
##Hi�u �i�n th� UAB =
35V.
T�nh �i�n tr� t��ng ���ng c�a to�n m�ch .T�nh c��ng �� d�ng �i�n qua c�c �i�n
tr�.T�nh c�c hi�u �i�n th� UAC v� UAD.
( 20(; 1.75A; 0.875A; 26.25V; 28.875V)
18. Tr�n h�nh v� l� m�t m�ch �i�n c� hai c�ng t�c
R1
R4
K2
###
K1 v� K2.
C�c �i�n tr� R1 = 12,5( , R2 = 4( , R3 = 6( .
K1#
Hi�u �i�n th� hai ��u �o�n m�ch UMN = 48,5V.##
a) K1
��ng, K2 ng�t. T�m c��ng �� d�ng �i�n qua c�c �i�n tr�.
b) K1 ng�t, K2 ��ng. C��ng �� d�ng �i�n qua R4 l� 1A.
T�nh R4.
M
N
c) K1 v� K2 c�ng ��ng, t�nh �i�n tr� t��ng ���ng c�a
c� m�ch, t� �� suy ra c��ng �� d�ng �i�n trong m�ch ch�nh ?
( 2.94A; 30(; 3A)#S� ph� thu�c c�a �i�n tr� v�o chi�u d�i, ti�t di�nv� v�t li�u
l�m d�y d�n - Bi�n tr�. 1. Tr�n m�t bi�n tr� c� ghi 25( - 1A. Con s� 25( - 1A
cho bi�t �i�u g� ?
Hi�u �i�n th� l�n nh�t ���c ph�p ��t v�o hai ��u bi�n tr� l�
bao nhi�u ?
Bi�n tr� l�m b�ng nicom c� �i�n tr� su�t 1.1.10-6(m, c� chi�u d�i

24m . T�nh ti�t di�n c�a d�y d�n d�ng l�m bi�n tr� ?
2. M�t d�y d�n l�m b�ng
Constantan c� �i�n tr� su�t ( = 0.5.10-6 (m, c� chi�u d�i l = 20m v� c� ti�t
di�n ��u S = 0.4mm2. Con s� ( = 0.5.10-6 (m cho bi�t �i�u g� ?
T�nh �i�n tr� c�a
d�y d�n ��. 3. ��t v�o hai ��u m�t cu�n d�y d�n l�m b�ng ��ng m�t hi�u �i�n th�
U = 17V th� c��ng �� d�ng
�i�n qua d�y d�n l� I = 5A. Bi�t ti�t di�n c�a d�y
d�n l� 1.5 mm, �i�n tr� su�t l� 1.7.1-8 (m . T�nh chi�u d�i c�a d�y d�n. 4. M�t
d�y d�n l�m b�ng ��ng d�i 30m, c� ti�t di�n 1.5mm2 ���c m�c v�o hi�u �i�n th�
30.8V.
T�nh c��ng �� d�ng �i�n qua d�y d�n n�y, bi�t ( = 1.7.10-8(m 5. M�t
b�ng ��n c� ghi 18V - 1A m�c n�i ti�p v�i m�t bi�n tr� con ch�y �� s� d�ng v�i
hi�u �i�n th� kh�ng ��i 24V. �i�u ch�nh �� bi�n tr� c� gi� tr� Rb = 12(. T�nh
to�n v� n�u nh�n x�t v� �� s�ng c�a b�ng ��n.H�i ph�i �i�u ch�nh bi�n tr� c� gi�
tr� bao nhi�u �� ��n s�ng b�nh th��ng ?
6. Hai b�ng ��n c� c�ng hi�u �i�n th�
��nh m�c l� U1 = U2 =6V, khi s�ng b�nh th��ng c�c b�ng ��n c� �i�n tr� t��ng �ng
l� R1 = 6( v� R2= 12( . C�n m�c hai b�ng n�y v�i m�t bi�n tr� v�o hi�u �i�n th�
U = 9V �� hai b�ng s�ng b�nh th��ng. V� s� �� m�ch �i�n tr�n v� t�nh �i�n tr�
c�a bi�n tr� ��. B�i t�p S� ph� thu�c c�a �i�n tr� v�o chi�u d�i, ti�t di�nv�
v�t li�u l�m d�y d�n - Bi�n tr�.B�i 1. M�t bi�n tr� con ch�y c� �i�n tr� l�n
nh�t l� 50(. D�y �i�n tr� c�a bi�n tr� l� m�t h�p kim nicr�m
c� ti�t
di�n 0,11mm2 v� ���c cu�n ��u xung quanh m�t l�i s� tr�n c� ���ng k�nh 2,5cm.
T�nh s� v�ng d�y c�a bi�n tr� n�y.Bi�t c��ng �� d�ng �i�n l�n nh�t m� day n�y c�
th� ch�u ���c l� 1,8A. H�i c� th� ��t v�o hai ��u d�y c� ��nh c�a bi�n tr� m�t
hi�u �i�n th� l�n nh�t l� bao nhi�u �� bi�n tr� kh�ng b� h�ng. B�i 2. M�t b�ng
��n c� ghi 18V - 1A m�c n�i ti�p v�i m�t bi�n tr� con ch�y �� s� d�ng v�i ngu�n
�i�n c� hi�u �i�n th� kkh�ng ��i 24V.�i�u ch�nh bi�n tr� ��n gi� tr� Rb = 12(.

H�y t�nh to�n v� n�u nh�n x�t v� �� s�ng c�a b�ng ��n.H�i ph�i �i�u ch�nh bi�n
tr� c� gi� tr� �i�n tr� bao nhi�u �� ��n c� th� s�ng b�nh th��ng. B� qua �i�n
tr� c�c d�y n�i. B�i 3. C� hai b�ng ��n m� khi s�ng b�nh th��ng c� �i�n tr�
t��ng �ng l� R1= 16( v� R2 = 12( . D�ng �i�n ch�y qua hai ��n ��u c� c��ng ��
��nh m�c l� I = 0,8A . Hai ��n n�y ���c m�c n�i ti�p v�i nhau v� v�i m�t bi�n
tr� v�o hai ��u �o�n m�ch c� hi�u �i�n th� U = 28,4V.T�nh �i�n tr� c�a bi�n tr�
�� hai ��n s�ng b�nh th��ng.Khi ��n s�ng b�nh th��ng, s� v�ng d�y c�a bi�n tr�
c� d�ng �i�n ch�y qua ch� b�ng 75% so v�i t�ng s� v�ng d�y c�a bi�n tr�. T�nh
�i�n tr� c�a bi�n tr� ?
B�i 4. Cho m�ch �i�n nh� h�nh v�. AB l� m�t# bi�n tr� c�
con ch�y C. L�c ��u ��y con ch�y C v� �i�m A �� bi�n tr� c� �i�n tr� l�n nh�t.
B
AKhi d�ch chuy�n con ch�y C v� ph�a B th� ��
s�ng c�a


b�ng ��n thay ��i nh� th� n�o?
Gi�i th�ch?
Bi�t �i�n tr� c�a b�ng ��n l� R� = 18(
. �i�n tr�
to�n ph�n c�a bi�n tr� l� 42( v� con ch�y C � �i�m #
ch�nh gi�a AB. Hi�u �i�n th� do ngu�n cung c�p
l� 46,8V. T�nh c��ng
�� d�ng �i�n qua ��n khi ��?
B�i 5. Cho m�ch �i�n nh� h�nh v�, trong �� b�ng ��n
c�
hi�u �i�n th� ��nh m�c 24V v� c��ng �� d�ng
�i�n
��nh m�c 0,6A ���c m�c v�i m�t bi�n tr� con ch�y
�� s�

d�ng v�i ngu�n �i�n c� hi�u �i�n th� kh�ng ��i 30V.
a) �� ��n s�ng
b�nh th��ng th� ph�i �i�u ch�nh bi�n tr�
c� �i�n tr� l� bao nhi�u?
B� qua �i�n tr� � d�y n�i.
b) N�u bi�n tr� c� �i�n tr� l�n nh�t l� 40(
th� khi ��n
s�ng b�nh th��ng d�ng �i�n ch�y qua bao nhi�u ph�n
tr�m ( %) t�ng s� v�ng d�y c�a bi�n tr�?
B�i 6. Hai b�ng ��n c� hi�u �i�n th�
��nh m�c l� U1= 12V, U2 = 24V, khi s�ng b�nh th��ng c� �i�n tr� t��ng �ng l� R1
= 6( v� R2 = 4( . C�n m�c hai ��n n�y v�i m�t bi�n tr� v�o hi�u �i�n th� U =
36V �� hai ��n s�ng b�nh th��ng.V� s� �� c�a m�ch �i�n .T�nh �i�n tr� c�a bi�n
tr� khi ��.* B�I T�P PH�N �I�N N�NGBa�i 1: Mo�t da�y da�n ba�ng nike�lin co�
chie�u da�i 100m, tie�t die�n 0,5mm2 ����c ma�c va�o nguo�n �ie�n co� hie�u
�ie�n the� 120V.1/ T�nh �ie�n tr�� cu�a da�y.2/ T�nh c���ng �o� do�ng �ie�n qua
da�y.H���ng da�n


# EMBED Equation.3 ###1/ �ie�n tr�� cu�a da�y:# EMBED Equation.3
�o� do�ng �ie�n qua da�y:# EMBED Equation.3 ###

###2/ C���ng



##Ba�i 4: Cho ma�ch �ie�n nh� h�nh ve�:H���ng da�n


1/ �ie�n tr�� t��ng ���ng cu�a R2 va� R3:# EMBED Equation.3 ###�ie�n tr�� t��ng

���ng cu�a ma�ch:# EMBED Equation.3 ### 6 = 36# EMBED Equation.3 ###2/ C���ng
�o� do�ng �ie�n qua ma�ch ch�nh:# EMBED Equation.3 ###Ma�: # EMBED Equation.3
###Ta co�: # EMBED Equation.3 ###V� R2 // R3 ne�n U2 = U3 = U2,3. Ta co�:#
EMBED Equation.3 #### EMBED Equation.3 ###3/ t = 5 ph = 300sCo�ng do�ng �ie�n
la�:A = UAB.I.t
= 24. 0,67. 300 = 4 824J


##Ba�i 5: Cho ma�ch �ie�n nh� h�nh ve�:H���ng da�n


1/ �ie�n tr�� t��ng ���ng cu�a R2 va� R3 la�:# EMBED Equation.3 ###�ie�n tr��
t��ng ���ng cu�a ma�ch:# EMBED Equation.3 ###2/ Hie�u �ie�n the� cu�a ma�ch:#
EMBED Equation.3 ###Ta co�: # EMBED Equation.3 ### = 6V. Ne�n ta co�:# EMBED
Equation.3 #### EMBED Equation.3 ###Co�ng sua�t to�a nhie�t tre�n t��ng �ie�n
tr��:P1 = # EMBED Equation.3 ###P2 = # EMBED Equation.3 ###P3 = # EMBED
Equation.3 ###


Ba�i 6: Mo�t be�p �ie�n co� ghi 220V � 1000W ����c s�� du�ng v��i hie�u �ie�n
the� 220V �e� �un so�i 2,5l�t n���c �� nhie�t �o� ban �a�u la� 20oC th� ma�t
mo�t th��i gian la� 14phu�t 35 gia�y.1/ T�nh hie�u sua�t cu�a be�p. Bie�t nhie�t
dung rie�ng cu�a n���c la� 4200J/kg.K.2/ Mo�i nga�y �un so�i 5l�t n���c �� �ie�u
kie�n nh� tre�n th� trong 30 nga�y se� pha�i tra� bao nhie�u tie�n �ie�n cho
vie�c �un n���c na�y. Cho bie�t gia� 1kWh �ie�n la� 800�o�ng.H���ng da�n


V� be�p ����c s�� du�ng �� hie�u �ie�n the� 220V �u�ng v��i hie�u �ie�n the�
��nh m��c cu�a be�p ne�n co�ng sua�t �ie�n cu�a be�p la� 1000W.1/ Nhie�t l���ng
cung ca�p cho n���c:# EMBED Equation.3 ### (v��i # EMBED Equation.3 ###)= 2,5.

4200. 80 = 840 000JNhie�t l���ng be�p to�a ra:Q = I2.R.t = P.t (v��i t = 14ph
35s = 875s)= 1000. 875 = 875 000JHie�u sua�t cu�a be�p:# EMBED Equation.3 ###2/
Nhie�t l���ng be�p to�a ra mo�i nga�y lu�c ba�y gi��:Q� = 2Q = 2. 875000 =
1750000J (v� 5l = 2. 2,5l)�ie�n na�ng tie�u thu� trong 30 nga�y:A = Q�.30 =
1750000. 30 = 52500000J = 14,6kWhTie�n �ie�n pha�i tra�:T = 14,6. 800 = 11680
�o�ng.


Ba�i 7: Mo�t ho� gia ��nh co� ca�c du�ng cu� �ie�n sau �a�y: 1 be�p �ie�n 220V �
600W; 4 qua�t �ie�n 220V � 110W; 6 bo�ng �e�n 220V � 100W. Ta�t ca� �e�u ����c
s�� du�ng �� hie�u �ie�n the� 220V, trung b�nh mo�i nga�y �e�n du�ng 6 gi��,
qua�t du�ng 10 gi�� va� be�p du�ng 4 gi��.1/ T�nh c���ng �o� do�ng �ie�n qua
mo�i du�ng cu�.2/ T�nh �ie�n na�ng tie�u thu� trong 1 tha�ng (30 nga�y) va�
tie�n �ie�n pha�i tra� bie�t 1 kWh �ie�n gia� 800 �o�ng.H���ng da�n


1/ V� ta�t ca� du�ng cu� �e�u ����c s�� du�ng �u�ng v��i hie�u �ie�n the� ��nh
m��c ne�n co�ng sua�t �a�t ����c ba�ng v��i co�ng sua�t ghi tre�n mo�i du�ng
cu�. Ne�n ta co�:# EMBED Equation.3 ###T��ng t�� t�nh ����c: I� = 0,45A va� Iq
= 0,5A2/ �ie�n na�ng tie�u thu� cu�a mo�i du�ng cu� trong 1 tha�ng:Ab = 1. Pb.t
= 1. 0,6. 4. 30 = 72kWhAq = 4. Pq.t = 4. 0,11. 10. 30 = 108kWhA� = 6. P�.t = 6.
0,1. 6. 30 = 132kWhTo�ng �ie�n na�ng tie�u thu�:A = Ab + Aq + A� = 312kWhTie�n
�ie�n pha�i tra�:T = 312. 800 = 249600 �o�ng


#Ba�i 8: Cho ma�ch �ie�n nh� h�nh ve�:#H���ng da�n


a/ �ie�n tr�� t��ng ���ng cu�a R2 va� R3# EMBED Equation.3 ###�ie�n tr�� t��ng
���ng cu�a ca� ma�ch# EMBED Equation.3 ###b/ Hie�u �ie�n the� gi��a hai �ie�m

MN# EMBED Equation.3 ###So� ch� cu�a vo�n ke�# EMBED Equation.3 ###c/ Hie�u
�ie�n the� hai �a�u R1U1 = UMN � U2,3 = 25,14 � 17,14 = 8VCo�ng sua�t to�a
nhie�t tre�n t��ng �ie�n tr��P1 = # EMBED Equation.3 ###P2 = # EMBED Equation.3
###P3 = # EMBED Equation.3 ###d/ t = 3ph = 180sNhie�t l���ng to�a ra tre�n
toa�n ma�ch# EMBED Equation.3 ###T�nh ba�ng calo: Q = 0,24. 9050,4 = 2172 cal



�i�n n�ng, c�ng v� c�ng su�t, ��nh lu�t Jun - Len- X�1. Tr�n m�t b�ng ��n c�
ghi 6V - 3W.Cho bi�t � ngh�a c�c con s� n�y ?
T�nh c��ng �� d�ng �i�n ��nh m�c
qua b�ng ��n ?
T�nh �i�n tr� c�a b�ng ��n khi n� s�ng b�nh th��ng ?
2. Khi m�c m�t
b�ng ��n v�o hi�u �i�n th� 30V th� d�ng �i�n ch�y qua n� c� c��ng �� 0,75A.T�nh
�i�n tr� v� c�ng su�t �i�n c�a b�ng ��n khi ��. T�nh nhi�t l��ng t�a ra � d�y
t�c b�ng ��n trong th�i gian 30 ph�t ?
N�u d�ng b�ng ��n n�y v�i hi�u �i�n th�
36V th� c�ng su�t ti�u th� c�a b�ng ��n l� bao nhi�u?
3. M�t b�ng ��n d�y t�c
c� ghi 220V- 100W v� m�t b�n l� c� ghi 220V - 400W c�ng ���c m�c
v�o � l�y �i�n 220V � gia ��nh.
a) T�nh �i�n tr� t��ng ���ng c�a �o�n
m�ch n�y.
b) T�nh c��ng �� d�ng �i�n ��nh m�c c�a m�i b�ng ��n
b) H�y ch�ng t� r�ng c�ng su�t c�a �o�n m�ch b�ng t�ng c�ng su�t c�a ��n v� c�a
b�n l�.
c) T�nh �i�n n�ng ti�u th� c�a hai thi�t b� tr�n trong th�i
gian 45 ph�t?
4. Cho 2 b�ng ��n l�n l��t c� nghi : 120V - 40W v� 120V - 60W.

Trong hai tr��ng h�p sau, t�nh c��ng �� d�ng �i�n qua m�i ��n v� cho bi�t ��n
n�o s�ng h�n?
Hai ��n m�c song song v�o m�ch �i�n 120V.Hai ��n m�c n�i ti�p v�o
m�ch �i�n 240V.5. Tr�n m�t �m �i�n c� ghi 220V - 770W.T�nh c��ng �� d�ng �i�n
��nh m�c c�a �m �i�n.T�nh �i�n tr� c�a �m khi ho�t ��ng b�nh th��ng.D�ng �m n�y
�� n�u n��c trong th�i gian 30 ph�t � hi�u �i�n th� 220V . T�nh �i�n n�ng ti�u
th� c�a �m.6. Tr�n hai b�ng ��n c� ghi 110V- 60W v� 110V- 75W.Bi�t t�ng d�y t�c
c�a hai b�ng ��n n�y ��u b�ng v�nfam v� c� ti�t di�n b�ng nhau. H�i d�yt�c c�a
��n n�o c� �� d�i l�n h�n v� l�n h�n bao nhi�u l�n?
C� th� m�c hai b�ng ��n n�y
n�i ti�p v�i nhau v�o hi�u �i�n th� 220V ���c kh�ng?
T�i sao?
7. Tr�n nh�n c�a
m�t ��ng c� �i�n c� ghi 220V - 850W.T�nh c�ng c�a d�ng �i�n th�c hi�n trong 45
ph�t n�u ��ng c� ���c d�ng � hi�u �i�n th� 220V.N�u hi�u �i�n th� ��t v�o ��ng
c� ch� l� 195V th� �i�n n�ng ti�u th� trong 45 ph�t l� bao nhi�u?
8. Tr�n m�t
b�ng ��n d�y t�c c� ghi 220V - 100W.T�nh �i�n n�ng s� d�ng trong 30 ng�y khi
th�p s�ng b�nh th��ng b�ng ��n n�y m�i ng�y 6 gi�.M�c n�i ti�p b�ng tr�n ��y v�i
m�t b�ng ��n d�y t�c kh�c c� ghhi 220V - 75W v� hi�u �i�n th� 220V. T�nh c�ng
su�t ti�u th� c�a m�i ��n v� c�a c� m�ch. Coi �i�n tr� c�a c�c b�ng ��n l� kh�ng
��i. 9. M�t d�y d�n l�m b�ng v�nfam c� p = 5,5. 10-8 (.m, ���ng k�nh ti�t di�n d
= 1mm v� chi�u d�i
l� l = 40m, ��t d��i hi�u �i�n th� U = 24V.T�nh
�i�n tr� c�a d�y.T�nh nhi�t l��ng to� ra tr�n d�y trong th�i gian 40 ph�t theo
��n v� jun v� calo. 10. D�y xo�n c�a m�t b�p �i�n d�i 12m , ti�t di�n 0,2mm2 v�
�i�n tr� su�t p = 1,1.10-6 (.m.T�nh �i�n tr� c�a d�y xo�n.T�nh nhi�t l��ng to�
ra trong 10 ph�t khi m�c b�p �i�n v�o hi�u �i�n th� 220V.Trong th�i gian 10
ph�t, b�p n�y c� th� �un s�i bao nhi�u l�t n��c t� nhi�t �� 25oC. Cho nhi�t dung
ri�ng c�a n��c 4200J / Kg.K. B� qua m�i s� m�t m�t nhi�t. 11. M�t �m �i�n c�

ghi 220V - 600W ���c s� d�ng v�i hi�u �i�n th� ��ng 220V �� �un s�i 2,2l�t n��c
T� nhi�t �� ban ��u l� 27oC. B� qua nhi�t l��ng l�m n�ng v� �m v� nhi�t l��ng
to� v�o m�i tr��ng.
T�nh th�i gian �un s�i n��c.
12. M�t b�p �i�n ho�t ��ng li�n t�c trong 1 gi� 30 ph�t � hi�u �i�n th� 220V.
Khi �� s� ch� c�a c�ng t� �i�n t�ng th�m 2 s�. T�nh �i�n n�ng m� b�p �i�n s�
d�ng, c�ng su�t c�a b�p �i�n v� c��ng �� d�ng �i�n ch�y qua b�p trong th�i gian
tr�n ?
13. Tr�n m�t b�ng ��n d�y t�c c� ghi 220V - 100W.T�nh �i�n n�ng b�ng ��n
s� d�ng trong 30 ng�y, m�i ng�y 4 ti�ng.M�c n�i ti�p b�ng ��n tr�n v�i m�t b�ng
��n kh�c c� ghi 220V - 75W v�o hi�u �i�n th� 220V. T�nh c�ng su�t ti�u th� c�a
m�i b�ng v� c�a c� m�ch. Coi �i�n tr� c�a c�c b�ng ��n l� kh�ng ��i.
Ch��ng ii. �i�n t� h�cI. ki�n th�c c�n nh�.
1. Nam ch�m c� hai c�c:
c�c B�c (N), c�c nam (S)
Khi ��t hai nam ch�m g�n nhau ch�ng t��ng t�c v�i
nhau: C�ng c�c ��y nhau, kh�c c�c h�t nhau.2. T� tr��ng l� kh�ng gian nam ch�m
ho�c xung quanh d�ng �i�n c� kh� n�ng t�c d�ng l�c t� l�n kim nam ch�m. 3. T�
ph� cho ta h�nh �nh tr�c quan v� t� tr��ng. Thu ���c t� ph� b�ng c�ch r�c m�t
s�t l�n t�m b�a r�i g� nh� cho c�c m�t s�t t� s�p x�p tr�n t�m b�a.4. ���ng s�c
t� ch�nh l� h�nh �nh c� th� c�a t� tr��ng. C�c ���ng s�c t� c� chi�u x�c ��nh.
5. Quy t�c n�m tay ph�i ( �p d�ng t�m chi�u d�ng �i�n, chi�u ���ng s�c t�)N�m
b�n tay ph�i, r�i ��t sao cho b�n ng�n tay h��ng theo chi�u d�ng �i�n ch�y qua
c�c v�ng d�y th� ng�n tay c�i cho�i ra ch� chi�u c�a ���ng s�c t� trong l�ng �ng
d�y8. Quy t�c b�n tay tr�i ( �p d�ng t�m chi�u d�ng �i�n, chi�u c�a l�c �i�n t�,
chi�u ���ng s�c t�)��t b�n tay tr�i sao cho c�c ���ng s�c t� h��ng v�o l�ng b�n
tay, chi�u t� c� tay ��n ng�n tay gi�a h��ng theo chi�u d�ng �i�n th� ng�n tay
c�i cho�i ra 900 ch� chi�u c�a l�c �i�n t�.9. C�ng su�t hao ph� do to� nhi�t
tr�n ���ng d�y t�i �i�n.P = # EMBED Equation.3 ### �� gi�m hao ph� �i�n n�ng



tr�n ���ng d�y t�i �i�n th� t�t nh�t l� t�ng hi�u �i�n th� ��t v�o hai ��u ���ng
d�y n�y.10.M�y bi�n th� G�m hai cu�n d�y s� c�p n1 v� th� c�p n2 ��t c�ch �i�n
v�i nhau trong c�ng m�t l�i th�p k� thu�t.N�u ��t v�o hai ��u cu�n s� c�p m�t
hi�u �i�n th� xoay chi�u th� � cu�n th� c�p xu�t hi�n d�ng �i�n xoay chi�u:
# EMBED Equation.3 ### = # EMBED Equation.3 ###
N�u n1 < n2 th� m�y c� t�c
d�ng t�ng th�.
N�u n1 > n2 th� m�y c� t�c d�ng h� th�.B�i t�p �i�n t� h�c##1.
T�m chi�u d�ng �i�n, chi�u l�c t�, c�c t� c�a nam ch�m trong c�c tr��ng h�p
sau:###
N
S
#########
I
#
F
I
F
I
#
F##
S
N#2. Ha�y xa�c
��nh c��c cu�a nam cha�m trong ca�c tr���ng h��p sau:#3. Ha�y xa�c ��nh ����ng
s��c t�� cu�a t�� tr���ng o�ng da�y �i qua kim nam cha�n trong tr���ng h��p sau.
Bie�t ra�ng AB la� nguo�n �ie�n:4. Ha�y xa�c ��nh c��c cu�a o�ng da�y va� c��c
cu�a kim nam cha�m trong ca�c tr���ng h��p sau:# 5. Xa�c ��nh c��c cu�a nguo�n
�ie�n AB trong ca�c tr���ng h��p sau:###6. V��i qui ���c: Do�ng �ie�n co�
chie�u t�� sau ra tr���c trang gia�y.

Do�ng �ie�n co� chie�u t��
tr���c ra sau trang gia�y.T�m chie�u cu�a l��c �ie�n t�� ta�c du�ng va�o da�y
da�n co� do�ng �ie�n cha�y qua trong ca�c tr���ng h��p sau:##7. Xa�c ��nh c��c
cu�a nam cha�m trong ca�c tr���ng h��p sau. V��i F la� l��c �ie�n t�� ta�c du�ng
va�o da�y da�n:8. Xa�c ��nh chie�u do�ng �ie�n cha�y trong da�y da�n trong ca�c
tr���ng h��p sau:#9. Cu�n s� c�p c�a m�t m�y bi�n th� c� 4000 v�ng, cu�n th� c�p
c� 250 v�ng.
a) M�y bi�n th� n�y c� t�c d�ng t�ng th� hay h� th� ?
b) Khi
��t v�o hai ��u cu�n s� c�p m�t hi�u �i�n th� xoay chi�u 220 V th� � hai ��u
cu�n th� c�p c� hi�u �i�n th� l� bao nhi�u ?
( 13.75V)
10. Ng��i ta mu�n t�i m�t c�ng su�t �i�n 4500W t� nh� m�y thu� �i�n ��n
m�t khu d�n c� c�ch nh�
M�y 65km. Bi�t c� 1km d�y d�n c� �i�n tr� 0,8(
.Hi�u �i�n th� gi�a hai ��u d�y t�i �i�nl� 25 000V. T�nh c�ng su�t hao ph� v�
to� nhi�t tr�n ���ng d�y.N�u c� �� hi�u �i�n th� hai ��u �o�n d�y t�i �i�n l�
220V m� truy�n �i th� c�ng su�t to� nhi�t tr�n ���ng d�y l� bao nhi�u ?
( 336.96 W ; 4349306W) 11. M�t m�y ph�t �i�n xoay chi�u cho m�t hi�u �i�n th� �
hai c�c c�a m�y l� 1800V. mu�n
T�i �i�n �i xa ng��i ta ph�i t�ng hi�u �i�n
th� l�n 36 000V.H�i ph�i d�ng m�y bi�n th� c� c�c cu�n d�y c� s� v�ng theo t� l�
n�o ?
Cu�n d�y n�o m�c v�o hai ��u m�y ph�t �i�n ?
C�ng su�t hao ph� s� gi�m bao
nhi�u l�n ?
( n2 = 20n1 ; 400l�n)Ch��ng iii. Quang h�cki�n th�c c�n nh�.
hi�n t��ng kh�c x� �nh s�ng - L� hi�n t��ng tia s�ng truy�n t� m�i tr��ng trong
su�t n�y sang m�i tr��ng trong su�t kh�c b� g�y kh�c t�i m�t ph�n c�ch gi�a hai
m�i tr��ng.- Khi tia s�ng �i t� kh�ng kh� sang m�i tr��ng trong su�t r�n, l�ng

th� g�c kh�c x� nh� h�n g�c t�i- Khi g�c t�i t�ng (gi�m) th� g�c kh�c x� c�ng
t�ng (gi�m) theo. - Khi g�c t�i b�ng 00 th� g�c kh�c x� b�ng 00 (tia s�ng truy�n
th�ng)Th�u k�nh h�i t� - C� ph�n r�a m�ng h�n ph�n gi�a.- M�t ch�m tia t�i song
song v�i tr�c ch�nh cho ch�m tia l� h�i t� t�i ti�u �i�m c�a th�u k�nh.3 tia
s�ng ��c bi�t c�n nh�:Tia t�i qua quang t�m cho tia l� �i th�ng.Tia t�i song
song v�i tr�c ch�nh cho tia l� �i qua ti�u �i�m.#Tia t�i �i qua ti�u �i�m cho
tia l� song song v�i tr�c ch�nh
(
(
(F'
O
F
F'
O
F
F'
O
F �nh
c�a v�t t�o b�i th�u k�nh h�i t�.V�t ��t ngo�i kho�ng ti�u c� cho �nh th�t,
ng��c chi�u v�i v�t.V�t ��t trong kho�ng ti�u c� cho �nh �o, c�ng chi�u v�i v�t.
V�t � r�t xa th�u k�nh cho �nh th�t l� m�t �i�m n�m t�i ti�u �i�m.�� d�ng �nh
A'c�a m�t �i�m s�ng A, ta v� 2 trong s� 3 tia ��c bi�t (� tr�n) xu�t ph�t t�
�i�m A, giao �i�m c�a hai tia l� (hay ���ng k�o d�i) l� �nh A'.�� d�ng �nh A'B'
c�u AB qua th�u k�nh ( AB vu�ng g�c v�i tr�c ch�nh, A n�m tr�n tr�c ch�nh) ta
ch� d�ng �nh B' c�a B r�i h� vu�ng g�c xu�ng tr�c ch�nh .#########
##########################Th�u k�nh ph�n k�.- Th�u k�nh ph�n k� c� ph�n r�a d�y
h�n ph�n gi�a.- Ch�m tia t�i song song v�i tr�c ch�nh
cho ch�m tia l� ph�n k�.2 tia s�ng ��c bi�t c�n nh�.- Tia t�i song song v�i
tr�c ch�nh cho tia l� c� ���ng k�o d�i �i qua ti�u �i�m .- Tia t�i �i qua quang
t�m ti�p t�c �i th�ng.

5. �nh c�a v�t t�o b�i th�u k�nh ph�n k�.- V�t ��t �
m�i v� tr� tr��c th�u k�nh ph�n k� ��u cho �nh �o, c�ng chi�u, nh� h�n v�t v�


lu�n n�m trong kho�ng ti�u c�.
- Khi v�t ��t � r�t xa th�u k�nh, �nh �o c�a
v�t l� m�t �i�m n�m t�i ti�u �i�m. C�ch v� �nh qua th�u k�nh t��ng t� nh� c�ch
v� �nh nh� c�ch v� �nh qua th�u k�nh h�i t�.M�y �nh.- M�i m�y �nh ��u c� v�t
k�nh, bu�ng t�i v� ch� ��t phim.- V�t k�nh c�a m�y �nh l� m�t th�u k�nh h�i t�.�nh tr�n phim l� �nh th�t, ng��c chi�u, nh� h�n v�t.M�t- Hai b� ph�n quan tr�ng
nh�t c�a m�t l� th� thu� tinh v� m�ng l��i.- Th� thu� tinh ��ng vai tr� nh� v�t
k�nh trong m�y �nh, c�n m�ng l��i nh� phim.- �nh c�a m� ta nh�n th�y l� �nh th�t
hi�n tr�n m�ng l��i.- Qu� tr�nh �i�u ti�t l� qu� tr�nh th� thu� tinh co gi�n ��
ph�ng l�n hay d�t xu�ng �� �nh tr�n m�ng l��i ���c r� n�t.- �i�m xa nh�t m� m�t
nh�n r� ���c g�i l� �i�m c�c vi�n Cv, �i�m g�n nh�t m� m�t nh�n r� ���c l� �i�m
c�c c�n Cc.
8. M�t c�n - M�t c�n th� nh�n r� nh�ng v�t � g�n nh�ng kh�ng
nh�n r� nh�ng v�t � xa. K�nh c�n l� th�u k�nh ph�n k�.
- K�nh c�n th�ch h�p
v�i m�t th� ti�u �i�m tr�ng v�i �i�m c�c vi�n.
9. M�t l�o
- m�t l�o nh�n
r� nh�ng v�t � xa nh�ng kh�ng nh�n r� nh�ng v�t � g�n. K�nh l�o l� th�u k�nh h�i
t�.
10. K�nh l�p
- L� th�u k�nh h�i t� c� ti�u c� ng�n d�ng �� quan s�t
c�c v�t nh�.
- V�t c�n quan s�t ���c ��t trong kho�ng ti�u c� �� cho �nh
�o l�n h�n v�t. M�t nh�n th�y �nh �o.#V� d�1. Tr�n h�nh v� ch� c�c tia t�i th�u
k�nh v� c�c tia l� ra kh�i th�u k�nh.#
H�y v� th�m cho �� c�c tia t�i v� c�c

tia l�.##
F
O
F'
V� d� 2. ��t �i�m s�ng S tr��c m�t th�u k�nh
h�i t� nh� h�nh v�.
#
H�y v� �nh S' c�a S qua th�u
k�nh.
S
F
O
FV� d� 3. ��t v�t s�ng AB tr��c th�u k�nh h�i t� nh� h�nh v�.
H�y v� �nh c�a AB qua th�u k�nh . �nh thu ���c l�
#
�nh th�t hay �nh �o ?
F
A
O
F'V� d� 4. ��t v�t AB vu�ng g�c v�i
tr�c ch�nh c�a m�t th�u k�nh h�i t� f = 18cm, c�ch th�u k�nh m�t kho�ng d =
36cm.
a) X�c ��nh v� tr� v� t�nh ch�t c�a �nh. ( �nh th�t hay �nh �o ?
c�ng chi�u hay ng��c chi�u ?
l�n h�n hay nh� h�n v�t?
)
b) Ch�ng t�
r�ng chi�u cao c�a �nh v� c�a v�t b�ng nhau.V� d� 5. ��t v�t AB vu�ng g�c v�i
tr�c ch�nh c�a th�u k�nh h�i t�c� ti�u c� f = 20cm, sao cho �i�m A
n�m tr�n

tr�c ch�nh v� c�ch th�u k�nh m�t kho�ng d. H�y x�c ��nh t�nh ch�t (th�t hay �o)
c�a �nh trong c�c tr��ng h�p :
a) d = 30cm.
b) d
= 10 cm.#.S*V� d� 6. H�y v� tia l� c�a c�c tia t�i h�nh b�n.
# - Nh�n x�t v� c�c tia l� n�y?
F
O
F�
V� d� 7: Cho h�nh v� nh� b�n:
S* Bi�t S� l� �nh c�a S#a)S� l� �nh th�t hay l� �nh �o?
S�*#b)V� sao bi�t th�u k�nh �� cho l� th�u k�nh ph�n k�c)B�ng c�ch v�, h�y x�c
��nh quang t�m O, hai ti�u �i�m c�a th�u k�nh �� chob�i t�p v� th�u k�nh B�i 1.
��t v�t AB vu�ng g�c v�i th�u k�nh h�i tu c� ti�u c� f = 17cm, th� th�y �nh A'B'
c�a AB l� �nh th�t
v� cao b�ng v�t. H�y x�c ��nh v� tr� c�a v�t v� �nh
so v�i th�u k�nh. B�i 2. ��t v�t AB vu�ng g�c v�i tr�c ch�nh c�a th�u k�nh h�i
t� c� ti�u c� f = 30cm, th� th�y �nh A'B' c�a
AB l� �nh th�t v� cao g�p
2 l�n v�t. H�y x�c ��nh v� tr� c�a v�t v� �nh so v�i th�u k�nh B�i 3. ��t v�t AB
vu�ng g�c v�i th�u k�nh h�i t� c� ti�u c� f v� c�ch th�u k�nh 28cm th� th�y �nh
l� th�t
v� cao b�ng n�a v�t. H�y x�c ��nh ti�u c� c�a th�u k�nh. B�i 4.
��t v�t AB vu�ng g�c v�i tr�c ch�nh c�a m�t th�u k�nh h�i t� c� ti�u c� f =
40cm. Nh�n qua th�u
k�nh ta th�y �nh A'B' cao g�p 2 l�n AB.H�y cho b
ࡱt �nh A'B' l� �nh th�t hay �nh �o?
T�i sao?
X�c ��nh v� tr� c�a v�t v� c�a �nh.
B�i 5. V�t AB ��t vu�ng g�c v�i tr�c ch�nh c�a m�t th�u k�nh h�i t� cho �nh th�t

A'B' cao b�ng v�t v�
c�ch v�t 64cm. H�y x�c ��nh ti�u c� c�a th�u
k�nh.B�i 6. ��t v�t AB tr��c m�t th�u k�nh v� c�ch th�u k�nh m�t kho�ng 30cm th�
�nh A'B' c�a AB ch� cao
b�ng n�a v�t. H�y t�nh ti�u c� c�a th�u k�nh.
B�i 7. Qua th�u k�nh h�i t�, v�t AB cho �nh A'B' = 2AB.�nh A'B' l� �nh th�t hay
�nh �o?
Bi�t ti�u c� c�a th�u k�nh l� 24cm. h�y x�c ��nh c�c v� tr� c� th� c�
c�a v�t AB.B�i 8. ��t v�t AB vu�ng g�c v�i th�u k�nh ph�n k� sao cho A n�m tr�n
tr�c ch�nh v� c�ch th�u
k�nh 30cm th� �nh c�ch th�u k�nh 18cm.T�nh
ti�u c� c�a th�u k�nh.
b) Bi�t AB = 4,5cm. T�m chi�u cao c�a �nh.B�i
9. ��t v�t AB tr��c th�u k�nh h�i t� c� ti�u c� f = 25cm, Cho �nh A'B', bi�t


×