K h o a n g thcfi g i a n diigrc b i e u d i l n b d i h i n h v e :
T
T
2T
t =—+ —= — .
3
3
3
Vdy chgn
dap an B.
3: L a z e A p h a t r a c h u m bufc x a c6 bifdc s o n g 0,45 |J.m v d i c o n g
Cau
suat 0 , 8 W . L a z e B p h a t r a c h u m bufc x a c6 bifdc s o n g 0,60 f^m v d i c o n g
suat 0 , 6 W . T i so giOfa so p h o t o n c u a laze B v a so p h o t o n c u a laze A
phat r a trong m o i giay l a :
A. 1
20
B.
C. 2
4
Giai
Taco:
n
"
he
T h e o de b a i :
'
he
= P^l^
'A
_
Vdy
chgn
dap an A.
Cau
4: T r o n g t h i n g h i e m Y - a n g v e g i a o t h o a a n h s a n g , n g u o n s a n g
p h a t r a a n h s a n g d o n she, c6 biTdc s o n g A . , . T r e n m a n q u a n s a t , t r e n
d o a n t h S n g M N d a i 2 0 m m ( M N v u o n g goc v d i h e v a n g i a o t h o a ) c6 10
van t o i , M va N l a v i t r i cua h a i v a n sang. T h a y a n h sang t r e n b a n g
a n h s a n g d o n sac c6 bLfdc s o n g X,, =
t h i t a i M l a v i t r i cua m o t v a n
giao t h o a , so v a n s a n g t r e n d o a n M N l i i c n a y l a :
A. 7
B. 5
C. 8
D. 6
Giai
K h i t h a y X, t h i so v a n t o i t r e n d o a n M N l a :
5X,
10?ti - k X , = k - ^
k = 6. N g h i a l a c6 7 v a n s a n g .
Vay t . t o n dap an A.
Q\h.\i tilt
thi T S D H , C D Mon VSt 11
153
Cdu 5: Phong xa va p h a n hach h a t n h a n
A . deu la p h a n ufng h a t n h a n toa n a n g liicfng
B. deu la p h a n ufng h a t n h a n t h u n a n g Itfo'ng
C. deu la p h a n ufng t o n g hgfp h a t n h a n
D. deu k h o n g p h a i la p h a n ufng h a t n h a n .
Giai
Phong xa va p h a n hach h a t n h a n deu la p h a n ufng h a t n h a n toa
nSng \\i(ing.
Vay chgn dap an A.
Cdu 6: T a i ncfi c6 gia toe t r o n g trirorng la g, m o t con He 16 xo treo
t h a n g dufng dang dao dong deu h6a. B i e t t a i v i t r i can bang ciia vat do
dan cua 16 xo la Al. Chu k i dao dong cua con lac nay l a :
A.
271.
'A/
B.
2K'
IT
c.
1
[7
^
27r V A /
Giai
K h i can bang: m g = k A /
Suy r a : T =
271,
A/
V g
Vdy chgn dap an D.
Cdu 7: D a t d i e n ap u = UoCoslOOTtt (V) vao h a i dau doan mach A B
gom h a i doan mach A M va M B mkc n o i t i e p . Doan mach A M gom dien
tror t h u a n
lOoVsQ
m^c n o i tiep vdri cuon cam t h u a n c6 do t i f cam L .
-4
Doan mach M B chi c6 t u dien c6 dien dung ^ - ^ F . B i e t dien ap gifla
271
h a i dau doan mach A M lech pha y
so vdfi dien ap giufa h a i dau doan
mach A B . Gia t r i cua L bang
A.iH
B.iH
71
C.
D . ^ H
-'-H
71
It
71
Giai
T a co:
= 200Q k h i
-300Q
L =
71
Z , = 100Q
L = -H,
Z, =
L = -H,
n
200Q
154
Giai Chi tiSt de thi T S DH, C D M6n Vat li
L = — H ,
ZL =100V2Q.
Dung phifcfng phap loai triT chon L = — H ,
= lOOQ.
71
Vay chgn dap an C.
Cau 8: Theo thuyet Itfcfng tuf a n h sang, phat bieu nao sau day l a s a i ?
A. T r o n g chan k h o n g , ph o t o n bay v d i toe do c = 3.10^ m/s doc theo
cac t i a sang.
B. P h o t o n cua cac a n h sang dcfn sSc khac nhau t h i m a n g n a n g
liTcfng khac nhau.
C. N a n g Itfo'ng cua m o t p h o t o n k h o n g d o i k h i t r u y e n t r o n g
chan k h o n g .
D . P h o t o n t o n t a i t r o n g ca t r a n g t h a i diJng y e n v a t r a n g t h a i
chuyen d o n g .
Giai
Chon
dap an D. P h o t o n t o n t a i t r o n g ca t r a n g t h a i dufng y e n va
trang t h a i chuyen dong.
CAu 9: M o t mach dao dong d i e n tCf l i tiJorng dang c6 dao dong d i e n
ttf t u do. Bie't d i e n t i c h ciic d a i t r e n m o t b a n t u d i e n l a
ciiofng do dong d i e n
CLTC
|aC va
d a i t r o n g mach l a 0,5 kyfl A . Thofi g i a n ng&n
nhat de dien t i c h t r e n m o t b a n t u g i a m tii gia t r i cifc d a i d e n nufa gia
tri
CLTC
dai
la
1
A. - a s .
3
B. — u s .
3 ^
C. - u s .
3^
D. - u s .
3
Giai
T a c o : (o = - ^ = - . 1 0 ' ' r a d / s .
qo 8
Thcfi gian n g ^ n n h a t de d i e n t i c h t r e n m o t b a n t u g i a m tCf gia t r i
X
16
8
cifc d a i den nufa gia t r i cifc d a i l a : t = — = — .10~^(s) = — |j.s.
6 6
3
Vdy chon dap an D.
Cau 10: T r o n g h i e n
tMng
giao thoa song n\J6c, h a i nguon dao dong
theo phiTofng vuong goc vdri m a t nvCdc, cung b i e n do, cung pha, cung t a n
so 50 Hz
difoTc d a t
t a i h a i d i e m S i va S 2 each nhau 10cm. Toe do t r u y e n
song t r e n m a t ni/dfc l a 75 cm/s. X e t cac d i e m t r e n m a t ntrdrc thuoc
di/orng t r o n t a m S i , b a n k i n h S1S2, d i e m m a p h a n tijf t a i do dao dong
vdfi bien do
CLTC
A. 85 m m .
d a i each d i e m S2 m o t doan n ga n n h a t b k n g
B . 15 m m .
Giai Chi tiSt 66 thi T S D H , C D M o n V a t II
C. 10 m m .
D . 89 m m .
155