Đề thi HSG TP Bắc Giang 2011 - 2012

BAi
1. (5,5
tli6m):
Cho
mpch
dign
(hinh
1),
v6i
U:6,3V,
Rr
:
&
:
R:
:,&
:2e,
Di€n
trd
cta
v6n
k6 rAt
lcyn.
die,
trO
cria
ampe
k6,
c6c
kh6a
K

vi
ddy
n6i
kh6ne
oarn
r.'a.
''"
R*
a)
Tfnh
s6
chi
cta
v6n
t6
t<nik,,
K,
d6;".0
.''i-
,.,
A
b)
Khi
K1
d6ng,
K2
m6;
v6n
kti
chi

Uu
:4,05V.
R1
HEy
tfnh:
-
Cucrng
cfQ ddng
di6n
cy
mpch
chinh?
r,rzI
-
Gi6
rri
cria
rliQn
tr6
&?
e
-
Higu
diQn
thiS
giira
hai
di6m
CB?
c)

Jfti
Kr,
Kz
d6u
d6ng.
Tfnh
s6
chi
cua
v6n
k6
vd
ampe
k6.
;
DE
THI
HAqSINH
GIOI
CAP
THArr{H
PHO
F{AM
HQC
20II
*
20t2
Mdn:
VgT
Li

LOp
9
Thdi
gian
ldm
hAi
t
S0
phrir
{I
flinh
l
ke.
ar'
vao
nguon
thi
cuong
d0
dong
di6n
qua
die*
PHONG
Cmo
DUC
VA
DAO
TAO
THAI{H

pHo'BAC
Ciexil'**
Bni
3.
!13i6y):Hai
ampe.k6
co
diQn
tro
lan
luq"r
rd
R1.
R2;
mQt
diQn
tro
R:3f)
va
m6t
nguon.cliQn-c6
hiQu
diQn
th6
|h6lg
d6i
u.
N6u
m6c
r-,aiamfiet6

,rdi,lil.,ji
,6",
,a,'rX,
tiep
vdi
dion
tro
R
vdo
ngu6n_tt
iro
crri,r6i
arnpe
r,e
rj
+-osllNj;k;
lr;;r;;';;
song
song
vdi
nhau
roi
mac
n6i
ti6p
vdi
di6n
tro
R
uao

nguon
;ir*.
kc
rhu
nh6t
chi
3,A,
ampe
tC
tnri
hai
chi
2A.
a)
Tfnh
dien
t1o
Rr,
R2
gua hai
ampe
b)
I{6u
chi
mic
truc
iiep
dion
rro
R

tru
R
le
bao
nhi6u?
Bii
1:1S
Oi6m;:
Cho
doan
m4ch
ctiQn
(hinh
2),haib6ng
<fdn
c6
ghi
E1:
2,5V-lW;
D2:
6V-3W.
eitit
ring
cdc
ddn
s6ns M
a)
Higu
diQn
th€

gifra
hai
diu
do4n
mpch
MN?
+'
b)
DiQn
tro
\
vd
rtiQn
tro
doan
mach
MN?
c)
HiQu
su6t
cria
clopn
mach
MN?
Iej
4
1S,S
Oi6m):
Cho
mpch

di€n (hinh
3);
Bi6t
U
:
6V,
r
:
0,5f);
3V-3W,
cdc
ddy
n6i
c6
diQn
trO
f.frOrg
OarJtS "
-
F{inh
2
R =:
1
,5Q,
cldn
gh
i
r
I i
a)

Tfnh
cli€n
J10
tuone
duong
cta.
m4ch
vd
cudng
d6
ddng
rliQn
dinh
mric
cta
ddn.
Edn
sang
nhu
th6
ndo?
b)
De
ddn
s6ng
binh
thucrng.
lguoi
ta
lay

mqt
dign
tro-
R*
m6c
th0m
vAo
mach.
Hoi
R*
phai
ma;
-rru:
il6';;.
,\
,vesud0va
tfnh gia
tri
cla
diQn
tr&
R*trong
m6i
cach
mic?
Bei
5.
(2
di6m):
Dua

hai
thanh
nam
ch6m
lai
gan
nhau
theo
chi6u
mfri
t6n
nhu
hinh
cria
hai
thanh
nam
ch6m
titip
xric
,huu
thi
c6c
dinh
s6t
roi
xuon!.
uie,,
tO
OiCu gi?

Ndu
c6
mQt
thanh
nam
ch6m
vd
m6t
thanh
I{inh
3
v0"
Khi
hai
eu'c
tuong
dd
chunpr
thdp
gi6ng
hQt
nhau,
hdy
dga
vdo
ket
lupn
trdn
dd
;lri

ra
cdch
tim
duoc
thanh
nio
lA
thanh
nam
chAm
ma
kh6ng
s*
dUng
th6m
vAt
dUng gi
kh
6c?
Ho
vd
ftn