Vật lý 12 tóm tắt lý thuyết và bài tập trắc nghiệm tập 1 (p2)

CHltawe
1:
DAD
nOWB
CB
m VJT It n -
TtM
TAT
Lt THUYfT VA
BAl
TAP
TRAC
MHlgM
-
Ti
Cau
23:
v = STT COS (nt +
-»
X
=
5
sin
(nt + ^)
^ '^os
(^^
^)
Cau
25:
= ^ = 8
cm;

o) = ^ ^ r =
1,26
s
Cau
27:
t = 0
-> X
=
0;
M^tCmax)
<t=>x
=
y4,-»At
= J =
0,25
5
Cau
30:
T =
27rJ^
=
0,4s;
W^^rnax)
= W =
^kA^
=^ A = Scm
Cau
31:
t = 0,Xo = ^,Vo < 0
Xn

1
^
A 2
=>
(p
= -
,
sin(p
> 0 ^
Cau
32:
;K:O =
4 cos
=
2V3
cm;
V
-
-4071 sin
=
-2071
cm/s
< 0
Cau
33:
a = -oi^x -^x = 3cm; x =
^4cos? =»
i4
=
2V3

cm/s
6
/l2
= + =»
|i7|
=
107rV3
cm/s
Cau
34:
T =
27r
-
= 0,4s
Cau
35:
T =
271
—
=
0,5
s
9
Cau
36:
=
Ao)
= ;4
-
=

2 m/s
Cau
37:
r = ^ =
0,5s
cj = 4n;A = ^ =
5cm;(p
= +|
A:
= 5
cos
^47rt
+ ^) =
-5sin(47Tt)
cm
Cau
38:
A
=
4cm, (o
=
^=10^,
m
s
56
tfAT
LY 12 - TOH TAT lY
THBYgT
VA BAl TAP TRAC
WBHlgM

- TAP 1
CHIfflHB1:BABDtNBCflH8l
(p
= 0 X =
A cos(lOt)
cm
Cau
39:
co =
^
=
40
rad/s
;^ = ^ =
5cm;
6J
71
/ 7r\
(p
=
^x
=
5cos
(lot - -j
cm
Cau
40:
(o =
27r/
=

47r
rad/s;A
=
20cm;
n
/ n\
(p
= + ^
X
=
20cos\4nt
+
-1
cm
Cau
41:
y4
=
4cm;
w = — =
7r
—;
w =—-
T
s ' ^ 2
X
=
A
cos
cm

Cau
42:T
= ^ =
0,314
6> =
20—,
100
s
^2
= +
Oi'
A
=
4cm
t
= 0,^0 =
2cm,
VQ > 0
41
42
43
44
45
46
47
48
49
50
B
A

B B
A
B B
C
A
A
51
52
53
54
55
56
57
58
59
60
B
C
B
D
B
A A
D
B
C
A:
=
4 cos
(20t-f)
sinq)

< 0
cm
Cau
43:
o) =
m
=
10VlO^;^2
= + _ =
ioV3
m/s=
Cau44:
Al=^=
1cm;let
= lo + Al =
36cm
Cau
45:
2^ =
8cm
=>A =
4cm;
A'^
= x^+^
->
6)
=
27r
rad/s
->

T = Is
57
CIHMRG1:DMB(IIGCI(HQC
WAT
It«
-
JtU
TAT IY
THBTfT
WA
BAl
TAP THAC
•BHICM-TAPI
Cau 46: Chieu dai 16
xo
ti
I5
nghich voi dp cung, cat
bat
16
xo
mpt
nura =^ do cung tSng gdp doi => chu ki giam
^/2.
Cau 47:
r'
- r =
27r
(Jf - Jf) =
0,083s

Cau
48:
r = =
o,314s;
m
= ^ = =
0,3125k^
=
312,5flf
Cau 49: Vmax
=
Ao)
= =^A
=
Vmax
J|
=
3cm
Cau50:
r = i^ =
0,314sfc
=
ma>2
=m(^)
=
160N/m
50
» \ /
Ti
Cau52:^=

P
1712
=
SO^f
Cau53:w=
1^=
10 rad/s A^
=^
+
^-^
A
= 4cm
Cau 54:
T^~m
-»
m
=
mj
+
rriz
=>
= + r| -»
T
=
I5
Cau 55:
At
= 7 = Is
4
Cau 56:

At
= =
0,25
s
Cau
57:
At
= - =
0,25s
4
Cau 58:
At
= - =
0,5
s
Cau 59:
t = 0,Xo =
ACTTI.VQ
<^'>Y~~^~\
T
A
=>At
=
*s
=
—
=
2cm
6
2.

Cau 60:
x =
2cm;
v <0 -*t
=
^
=
l s
6
3
VAT
It« - Tin TAT It
THBYfT
VA BAI TAP TRAC
IRHI|M
- TjP 1
CHa0N61:BABB9NGCtfl
61 62 63 64 65 66 67 68 69 70
C A
D
C
B
A
D
C A A
71 72 73 74 75 76 77 78 79 80
C
D
B
A

B
C C A C
B
Cau61:
t =
0,Xo
=
0,i;o
<
0;^=
1,5
-»
At
=
1,5T ->
CO
4
Idn
qua
vjtrix
=
-2cm
t
= 0
•
•• \
-4
-2 0 +4
Chii
y:

trong mpt chu ki c6 hai Ian vat di qua
vi
trf x = 2cm.
Cau 62:
=
Wt =^
\x\ ^-^
A
=
6cm;
max
= 10 rad/s ->
7 =
0,628
s
Cau63:a>= /^=107r —;
yjm
s
A^=x^
+
A
=
6cm;
XQ
=
3cm
= -;
T
A
At

=
—
cos =
2—
=
6cm
6
Z
-6
t
x
=
3cm -
-
+6

0
^
mi
=
2505,m2
=
1605f
Cau 65:
M = 0-*
IQ
=
Imax
-A =
36cm

CHlAfNG l:DA00QNGCdH9C
tfAT
lY
12
-
TUM TAT
LY THUYgj
VA BAI TAP TBAC NGHIEM
- TiJP 1
Cau
66:
- = 0,05s 7 = 0,25 w = 10n~
4 S
,2 _
Cau 67:
Cau 68:
k
= mo)^ = 50 N/m
A/
= ^ = 0,05m; F^^ = 100(0,05 - 0,03) = 2N
20
Cau
69:
A = 3cm = 0,03m; T = — = 2n^
9
Cau 70;
Cau 72;
^,
^^n(7na;«:) k(M + A)
M

= 0,04m; -H^ =
r-r—
-r
= 7
PdKmin) - A)
A/
=
0;
F^nimax)
=
kA;
Umax
=
Aa)^=A^^m
=
O.Skg
AZ = COSm >
A,
F^himin)
= KM - A) = IN,
F^n(max)
= HM+A) = 9N
Cau
75:
Wa=W-Wt=
^k^A^
- x^) = 0,009/
Cau 77:
Cau 80:
W = lmo)^A^ = im [^f => ^ = 4cm

2A
= 8cm=^A =
0,04m,
W =
\moP-A^
= 0,008/
81 82 83 84 85
86 87 88 89
90
D A D D
B
A
B B B
D
91 92
93 94
95 96
97
98
99 100
D
D
A C D A A A
C B
Cau
81:
Wt
= W-W^ =
\m{vlax
- v^) =

0,018/
Cau S2:W^ = 3Wt ^ AWt = W =^ X = ±^ = ±6 cm
WAT
lY
12
- TdM
TAT
lY THUYfT
WA BAI TAP TBAC
HGHigM -
TAP
1
CHtfflHB
1:
DAO
njlllG
M Hn
Cau
83: Aco
= lOO/r
co
= lOn
rad
r = 0,2
s->r^^„5^„5
= 0,1s
1,
Cau 84: T^^ng ndng - ^ Tdao dQug - 0,25 S
Cau
85:

W = ^kA^ = \m.v^ax k = 125 N/m vam = 0,2kg
Cau
90:
=
M^t->
^ =
±
^ = ±5cm
Cau
93:
T^~l -*
I
= - =^ = - Ti =^ T = 0,6s
Cau94:/2~i-^/
=
/i
+
/2=>5^
=± + j-^=^f = 4,BHz
Cau
95:
r = —
2rr^
-
= 1,6s
9
Cau
96:
J = = 2,23s
Ti

^92
-^T2-Ti
= -0,01s <
0:
dao
dong nhanh
0,01s
Cau98:J=
1^
=
^/IMT2
=
yflM
.100% =
20o/o
"1
'1 "1
Cau
99:
2n
T At „
/i-0,256
At ,
40cm
Cau
100:
2n f^ = ^]2n
yjg 39 yj
1-7,9
At ,

^r-^

= — -»/ = 151,1cm
9
40
101 102
103
104
105
106 107
108
109
110
B
A
A
B
B
C
C A
C
B
111 112 113
114
115
116
117
118 119
120
A A B

D
11
CWMHGI:
BA8fltaGC«ll«C
V*l 1*
K - TtM
TAT
t*
THBYf
T
»A
BAI TAP TBAC
NGHtEM
- HP 1
60
"V 5 50
cm
Cau 102:
=x^ +^
v&i A
=
lao,x
= la
CO'
vko)
=
J
->
17
=

20V3
cm/s
Cau 104:
2A = Acm =^A = 2cm - = 0,75 s
4
CfiulOS:
g' =g + a = g+^ = ^
T
9
3
X
2
5''
Cfiu 106:
F = qE/'y/g^g' = g-a = g-
l
\ct\E
m
r
= 271
5
7
= 1,29s
Cau
107:
F =
qE/'/'g^g'
= g + a = g +
\q\E
m

r
=
2n
Caul08:F
=
q£l^->^'=V?T^
=
j5'
+
(^y
T'
= 27r
Z
-
= 2,21s
CSu 110:
A<p
=
271
>l^a;^ = ylj + ^2 =
lOcTTi
-»Vmojc
=
lOOcm/s
VAT LY
IZ-TtM
TAT
It THBYfT WA
BAI TAP TBAC
WHIgM

-
TAf 1
CHlfini61:B*B0tll6CtfH9C
Cau 112:
A(p
=^ yA
=
yjAl
+ Aj = 5cm
Cau 113:
A =
yjAl
+
A^
+
2i4i>42COS
(<P2 - (Pi) = 9cm
Cau 114: Dap an
A
vd B
sS
khong chpn vi dao dpng
2
cung pha vol
dao dpng 1, khong thoa phucmg trinh dao dpng tong hgp. Neu chgn
C thi
khong thoa pha ban dau cua dao dgng tong
hgp.
Dap dn D la phu hgp vi khi
hai dao dong ngu(/c

pha,
pha
ban ddu cua dao dpng
tSng
hgrp
ciing pha ban
ddu vai dao dgng thdnh phdn c6 bien
dg Ian
han.
CHlfdNG
2:
SdNG
Cd
VAT LV 1? - TdM TAT li
THUYgT
VA BAl TAP TRAC
NGHI|M
- TAP 1
CHLTonVG
2
SONG CO
^ VAN BE
1;
BINH NGHJA SONG CO
• Song ca hgc la nhung dao dpng car
Ian
truyen trong moi truong
vat chat theo thai gian.
Phuomg trinh song:
u =

acos(6)t
+
q))
• Song ngang: Song c6 phtromg dao dong vuong gdc vai phuomg
truyin song.
• Song
dQc:
Song c6 phuong dao dong trung voi phuomg truygn
song.
Song
CO
khong truyen duac trong chan khong.
Khi song truyen tir moi truong nay sang moi truomg
khdc,
tan so
song khong doL
• Bir6'c s6ng(A):
- QuSng duong song truyen dugc trong mpt chu ki.
- Khoang each ngdn nhdt giiia 2 diem tren phuomg truyen
song ma dao dgng ciingpha.
X
=
vT
= J
Trong
do:
A: Buac song (m)
v: Toe do truyen song
Bai
tap mau;

Mgt nguon song
dao
dpng
c6
phuomg trinh
u
=
2
cos(160;rt) (u tinh bSng cm,
t
tinh bang giay) tao ra song c6 toe dp
Ian
truyen trong khong khi v = 330m/s.
a. Xac dinh bien
dp,
chu ki, tan so.
b.
Tinh budc song trong khong khi.
c. Trong 2s s6ng truySn dupe quSng du6mg b3ng bao nhieu Ian
bu6c s6ng.
d. S6ng tren truyen tir khong khi vao nu6c, biet v^n toe truyen
s6ng trong nuae
1^
1452
m/s,
tinh bu6e song trong nu6c.
DAT LY
12
TdM TAT
lY THUYfT

tfA
BAI TAP
TBAC
llfiHIgM
-
TAP
1
CNIfdRG
2:
SdNG
Cd
Giai:
u =
2cos(1607rt),Vi
=
330 m/s,
=
1452 m/s
a.
a
= 2cm, T
= =
0,0125s, f =
i
= 80Hz
b.
=
VjT
=
330

X
0,0125
=
4,125m
— —
—
—
1
—
^
—
1
An
^' Xi
~
vT
~
T
~
0,0125
~
d.
=
VzT
=
1452
X
0,0125
=
18,15m

Bai tap
1:
Can 1: (De thi tot nghiep nam 2007). Phdt bieu n^o sau day
\h
dung khi
noi ve song ca hpc?
A. Song am truyen dugc trong chan khong.
B.
S6ng dpc 1^ song eo phuomg dao dpng vuong g6e voi phuomg
truygn song.
C.
Song dpc la song eo phuong dao dpng trung vdi phuong truyen song.
D.
Song ngang la song c6 phuomg dao dpng trung voi phuomg truySn
song.
Can 2: (De thi tot nghifp nam 2008). Khi noi ve song ca hpc, phat bieu
nao sau day la sai ?
A. Song ca hpc la
svr
Ian truySn dao dpng ca hpc trong moi truong vat
chat.
B.
Song ca hpc truyen dupe trong tat
ck
cdc moi trudng
rSn,
16ng,
khi
va chan khong.
C. S6ng am truyen trong khong khi

1^
song dpc.
D.
Song ca hpc Ian truyen tren mat nu6e
1^
s6ng ngang.
Cau 3: (De thi dai hpc nSm 2009) Buac s6ng 1^ kho^g edeh gifra hai
diem
A. Tren cimg mpt phuang truyen s6ng dao dpng tai hai diem do
ngupre
pha.
B.
Gan nhau nhat tren cung mpt phuang truyen s6ng ma dao dpng tai
hai diem do cung pha.
C.
Gan nhau nhat ma
dao
dpng t^ hai diem do cung pha.
D.
Tren cung mpt phuang truyen song ma dao dpng tai hai diem do
cimgpha.
mm t.
SONG
cd
V*T
LY 12 - TiM TAT LY
THUYfT
VA
BAI
TAP TBAC

NGHlf
M
- TilF 1
Cau 4: Goi A
la
buac song cua mpt song ca. Khoang each giua hai diem
gan nhat tren phirorng truyen song dao dong eiing pha bang
A. A/4.
B. A. C.
A
/2. D.
2
A.
Cau 5: Mpt son^
am
Ian truySn trong khong khi voi van toe 350m/s,
eo
buac song 7m. Tan so song la
A. 5000Hz. B. 2000Hz. C. 50Hz. D. 500Hz.
Cau 6: Mot diem
A
tren mat nuac dao dpng voi tan s6 lOOHz. Tren mat
nuac nguai ta do duge khoang each giua 7 gem 16i lien
tikp
la 3cm. Khi do
van toe truyln song tren mat nuac la
A. 50em/s. B. 50m/s. C. 5 cm/s. D. 0,5cm/s.
Cau
7:
Mpt nguai quan sat song tren mat h6

thhy
khoang each giiJa hai
ngon song lien
iiip
bang 2m
va
c6
6
ngon song qua truae mat trong
8s.
Van t6c truyen song tren mat nuae la
A. 3,2m/s. B. l,25m/s. C. 2,5m/s. D. 3m/s.
Cau 8: (De thi dai
hQC
nam 2010). Tai mot diem tren mat chat long c6 mot
nguon dao dpng vai tan s6 120 Hz, tao ra song 6n dinh tren mat chat long.
Xet 5 ggn loi lien tiep tren mot phuang truySn song,
a
vS mot phia so voi
ngu6n,
ggrn
thu nhdt each gan thu nam 0,5 m.
T6C
dp truyen song la
A. 12 m/s.
B.
15 m/s. C. 30 m/s. D. 25 m/s.
Cau
9:
Mpt song am c6 tan so xac dinh truyen trong khong khi va trong

nuac voi van t6c ISn lugrt la 330 m/s va 1452 m/s. Khi song am do truyen
tvr
khong khi vao nuac thi buac song cua no se
A. giam 4,4 Ian. B.giam41an. C. tang 4,4 Ian. D. tang 4 Ian.
Cau 10: (De
thi dai hqc
nam 2007) Mpt nguon phdt song dao dpng
theo phuang trinh
u =
acos(207tt) (cm)
vdi t
tinh bang giay. Trong
khoang thai gian
2 s,
song n^y truyen
di
duge quSng duomg bang bao
nhieu ihn buac s6ng
A. 20.
B.40. C.
10.
D.30.
68
yAT LY 12 - TiM TAT L»
THUYgT
tf
A BAI TAP
TRAC
HBHIfM - TAP 1
CHlfdHIB

2:
sane
Ctf
^ VAN DE 2; QUA TRINH TRUYEN
SONG
-
DQ LECH
PHA
-
PHU^aNG TRINH TRUYEN
SONG
• Qua trinh truyen song:
- Qua trinh truySn nang lugng.
- Qua trinh truyen pha dao dong (trang thai dao dong)
- Cac phan tir vat chat dao dpng tai cho, khong bj Ian truyen.
•
DQ
lech pha:
/V<p
= ^
- Cung pha:
A<p
= k2n
(2 diem gin nhau nhat tren phuang truyk song dao dpng cung
pha: Acp
= 2n)
- Ngu"(/c pha:
A<p
=
TT

+ k2n
(2 dilm
gin
nhau nhat tren phuang truyen song
dao
dong
ngucc pha: A(p
=
TT)
- Vuong pha: A(p
= | + kn
(2 diem
gan
nhau nhit tren phuang truyen song
dao
dong
vuorjg pha:
A(p
~ ^)
X
la
khoang cdcx giua hai diim cdn tinh
do
l?ch pha
(x vdX
cung
don
vi)
• Phu-ong trinh truyen s6ng
Song i,

J
/; n iheo phuang chieu Ox
-
Phx( g
(rinh song
t^
ngu6n: uo = acos(6>t)
-
Phj(
ig tiinh s6ng tai M cdch O mot doan x do O truygn tai:
0^
X
UM
=
acos
/
2KX\
r-T-)
- Phucmg trinh song tai M truac nguon O each O mpt doan x:
M
X
"0
UM
-
acos
I
fa)t
+
cHUifiG
2:

SAMG
ca
»iT
li
n
-
TiM
TAT
tt
TWYfT
VA lAi
ikr
THAC
•emCM-TAPi
Bai
tap mau;
BM
1: Nguon song O dao dpng
voi
phuang
trinh
uo = 5cos(57rt) (cm) tao ra
song Ian truyen voi toe dp 24cm/s va gia su trong qua
trinh
truyen song bien
do song khong doi.
a.
Tfnh
dp lech pha cua mot diSm M tren phuomg truyen s6ng ngu6n
O

biat
OM
= 3,2cm.
b.
Tinh
dp l?ch pha cua 2 diem P va Q tren phuang truyen song va c6
khoang
each
toi
ngu6n O Ian
lupt
\k 2,4 den 3,6cm.
c. Wik phuang
trinh
song tai Q do nguon O
truygn
toi.
Giai:
uo =
5cos(57rt)
(cm),v = 24cm/s
Buacsong:
X
= vT = v-=24^ = 9,6cm
°
to Sn
a.
X
= OM = 3,2cm:
A(p

= =
ZTT-^
=
A,
9,6 3
h.x =
OQ-OP
= 3,6 - 2,4 = 1,2cm:
A(p
= ^ = J
c.
X
= OP = 3,6cm:
UQ
= 5 cos
(STA
- ^) = 5 cos ^5ut - ~j
Bai
2: Song ca truyen trong mpt moi tnrang dpc theo tryc Ox voi
phuang
trinh
U=cos(20t-4x) (cm) (x
tinh
bSng met, t
tinh
bSng
giay).
Tinh
van toe truyen song.
Giai;

u - cos(20t - 4x)
<->
u =
acos
(a)t - ^)
2nx ,71 w 7r20 ^ ,
—_
= 4x =>
A
= - m -* V = A/ = A— = -— = Sm/s
A.
2 2n 2 Zn
Bai
tap 2
Cau
1:
Phat
biSu n^o sau day
1^
sai
khi
n6i ve qud
trinh
truyen s6ng:
A.
Qud
trinh
truySn song 1^ qud
trinh
truyen dao dpng trong m;

truomg
dan
hoi.
B.
Qua
trinh
truyen song \k qud
trinh
truyen nSng lupng.
C.
Qud
trinh
truyen s6ng la qua
trinh
truyen pha dao dpng,
D.
Qud
trinh
truyen s6ng la qua
trinh truyln
c&c
phSn
tii
v§t chat.
VAT
li n - HM
TAT
it
TmiYgT
wA

BAI
IAP
T»AC
twxtui
-
TAP
I
CHtfdllGZiSDNGCtf
Cau 2: Mpt song am c6 tin so 450Hz Ian truyen vai van t6c 360 m/s trong
khong
khi. Dp lech pha giua hai diem
each
nhau 0,2m tren mpt phuang
truyen
song la
A.
^(p=0,57u.
B.
A^=l,5;r.
C. A^=2,5;r. D.
l^cp=\5K.
Cau 3: Song truyen tu O den M vai
buac
song 60cm.
Diem
M
each
O
mpt
doan 45cm thi

tinh
chit
cua song tai M la:
A.
M dao dpng nguprc pha
voi
O. '
3;r
B.
M dao dpng cham pha hom O la ~.
-hit
C. M dao dpng nhanh pha han O la .
D.
M dao dpng cung pha vai O.
Cau 4: Mpt song c6 tan so 500Hz, t6c dp Ian truySn 300m/s. Hai
dilm
gan
nhau nhat tren phuang truyen song phai
each
nhau gan nhat mpt khoang bao
nhieu
de
giiia
chung c6 dp lech pha bang y
rad
?
A.
0,1 m. B. 0,1 cm. C. 10 m. D.
1
cm.

Cau 5: (De thi cao dang nam 2009) Mpt song ca c6 chu ki 2 s truyen v6'
toe dp 1 m/s. Khoang
each
giiia
hai diem gan nhau nhat tren mpt phuang
truyen
ma tai do cac phan tu
moi
truang dao dpng
nguac
pha nhau la
A,
0,5m. B. 1,0m. C.2,0m. D. 2,5 m.
Cau 6 : (De thi dai hpc nSm 2009) Mpt song am truyen trong thep vai van
toe 5000m/s. Neu dp l?ch cua song am do a hai diem gan nhau nhat
each
nhau Im tren cung mpt phuang
truy6n
song la thi tan s6 cua song bang:
A.
1000 Hz B. 1250 Hz C. 5000 Hz D. 2500 Hz.
Cau 7: Song truyen tren day voi van toe 4m/s. Tin so cua song thay doi tu
22Hz
din 26Hz.
Dilm
M
each
nguon mpt doan 28cm
luon
dao dpng vuong

pha voi ngu6n. Buac song truySn tren day la:
A.
160cm. B. 1,6cm. C. 16cm. D. 100cm
R3
mm 2:
sdNG
cd
VATLY
12-TI>MTAT
LY
THUYfT
VA BAI TAP
TRAC
HBHIEM-TAPI
Cau
8: (De thi dai hoc nam 2011) Mpt song
hinh
sin
truygn
theo phuomg
Ox
tu nguon O vai tan s6 20 Hz, c6 toe dp trayen song nkm
trong
khoang tu
0,7 m/s den 1 m/s. Goi A va B la hai
diem
nam tren Ox, a cung mgt phia so
voi
O va each nhau 10 cm. Hai phan tu moi truong tai A va B
luon

dao
dong
nguge pha vai nhau. Toe do truyen song la
A.
lOOcm/s. B. 80cm/s. C. 85 em/s. D. 90em/s.
Cau
9: Cho mot song ngang c6 phuong
trinh
song la u = 5cos
0,1
2
mm,
trong
do x
tinh
bang cm, t
tinh
bang
giay.
Phan tic song M c6
XM
= 3cm
a
thai
diem
t = 2s c6 do dai
A.
UM 0 mm.
C.
UM = 5 cm.

B.
UM = 5 mm.
D.
UM = 2,5 cm.
Cau
10: Mot song ca hoc Ian truyen
trong
mot moi truong vat chat tai mpt
2;r
cm.
diem
each nguon x (m) c6 phuang
trinh
song
w
= 4cos
Van
toe truyen song
trong
moi truong do c6 gia tri
A.
2m/s. B. Im/s. C. 0,5m/s. D. 3m/s.
Cau
11: (De thi tot nghi^p nam 2009) Mpt song ngang
truyin
theo
chilu
duong
trye Ox, c6 phuang
trinh

song la u =
6cos(AM
-
G,02;w);
trong
do
u
va
X
tinh
bang cm, t
tinh
bang s. Song nay c6
buac
song la
A.
150 cm. B. 50 cm. C. 100 cm. D. 200 cm.
Cau
12: (De thi cao dkng nam 2009) Mpt song truyen theo true Ox voi
phuang
trinh
u =
acos(47tt
- 0,027tx) (u v^ x
tinh
bSng cm, t
tinh
bang
giay).
Toe

dp truyen cua song nay la
A.
100 cm/s. B. 150 cm/s.
C.
200 cm/s. D. 50 cm/s.
Cau
13: (De thi cao dkng nam 2008) Song ca c6 tan so 80 Hz Ian
truySn
trong
mpt moi truong voi van toe 4 m/s. Dao dpng cua cac phkn tu vat chat
tai
hai
diem
tren mpt phuong
truySn
song each nguon song nhiJng doan Ian
lupt
31 cm va 33,5 cm, l?eh pha nhau goe
A.
— rad.
2
B.
71
rad.
C.
2n rad.
D.
- rad.
3
VAT lY

12
- T6M TAT I*
THUYfT
VA'BAI TAP
TBAC
HEHIEM-TAPI
CHIfdNG
2:
SdNE
Clf
Cau
14:
Tren
soi day OA, dau A c6
dinh
va dau O dao dpng
dieu
hoa c6
phuong
trinh
uo = 5cos(5
TC
t) (cm). Van toe truyen song tren day la 24cm/s
va
gia su
trong
qua
trinh
truySn
song bien dp song khong d6i. Phuang

trinh
song tai
dilm
M each O mpt doan 2,4cm la:
A.
Uj^
= 5cos
2
C. = 5cos
{cm).
{cm).
B.
Uf^, - cos
4
{cm).
D.
= 5cos
4y
{cm).
Cau
15. Tao song ngang tren mpt day dan hoi Ox. Mpt
diem
M each
ngu6n
phat song O mpt khoang 50 cm c6 phuang
trinh
dao dpng
UM
=
2eos[7r(t

-1/20)]
(cm), van toe truyen song tren day la 10 m/s. Phuong
trinh
dao dpng cua nguon O la:
A.uo
= 2sin7c(t + 1/20) (em). B.
UQ
=
2cos(7rt
-
7r/20)
(em).
C.Uo
= 2sin(nt -
7c/20
) (cm). D.
UQ
= 2cos7rt (cm).
VAN
DE
3:
GIAO
THOA
SONG
VOI
2
NGUON
KET
HOP
CUNGPHA

r
•
Giao
thoa la su t6ng hop cua hai (hay nhieu) song ket hop
trong
khong
gian,
trong
do eo nhung cho c6
dinh
ma bien dp song dupe
tang
cuong
hoac
bi
giam
bat (hay
tri?t
tieu).
Dilu
kien
giao thoa
(dieu
ki?n
hai ngu6n kit hop): Hai song phai
xuSt
phat tir hai nguon
ciing
tan so,
cung

phumtg
dao
dong,
c6 dp
lech
pha
khong
dSi theo
thoi
gian.
Bien
dp song tong hap:
^
=
2A cos—^
2
Acp
la dp lech pha cua hai song tai M
»AT
It IZ
- TtM
TAT li
THBYfT
VA
BAI
TAP
TRAC
NGHIEM - TAP
1
V| tri cac diem dao dpng v6i bien d9 circ dai: (ggn Idi)

d^-d,=kX
+
Hi$u
duang
di
bang
so
nguyen
Idn
buac
song,
•y
Vf tri cue dgi
bac
n itng vai
k
= n
(v&i
n
= 0; ±
1;
± 2 )
• V| tri c^c
diem
dao d^ng vol
bien
d? eye
tieu:
(ggfn 16m)
d,-d,=

.4
,
2)
+
Hieu
duang
di
bdng
s6
ban
nguyen
Idn
buac
song
(so le
ciia
nua
buac
song)
+
Vi tri cue
tieu
thii
n ung
vaik
= n-
1 (vai n
= I; 2;
3 )
Hinh

anh giao thoa:
-
6
vi
tri
duang trung true eua Si va S2 luon la day e\re dai.
- Ve
2
phia cua duang trung true la nhirng day euc dai va cue
tieu
xen ke nhau
hinh
dang Hyperbol.
- S6 cue dai tren doan S1S2:
SiS^
<kX< S^S.
- S6cvrctieutrendoanSiS2:
>A:= ?
SS
gid tri cua
k
Id
so
cue dgi hay euc tiiu
tren
doan
S1S2.
- Khoang
each
giua hai c\rc dai lien tiep bang khoang

each
gifta
hai
evrc
tieu lien tiep tren doan S1S2 va bang
—
Chii
v; Neu
hai
nguSn
dao
dgng
ngu(rc
pha,
ta doi cho
cong
thuc
eua cue dgi cho
cue
tieu
va
ngu^rc
Igu
VAT
Vi
1Z
-
TllH
TAT
tV THUYgT

VA
BAI
TAP TBAC
NBHIgM - TAP
1
CHirifRG
I:
SlNG
Ctf
Bai
tap mau;
6
mat
nuac,
c6
hai ngu6n k6t hop A,
B
dao dong
theo
phuomg
thang dung
vai
phuomg
trinh
u^=Ug^20co^{\Qnt){mm).
AB
=
26em
va
t6e

do truyen song la
50
cm/s. Coi bien do song khong doi
khi
song truySn di.
a.
Cac diem tren du6ng trung true cua AB dao dohg vai bien do
bang bao
nhieu?
b.
Tinh bien do song
t^i
M
6
mSt
nuac
each
hai nguon Ian luot
la
21 cm va 26 cm.
c.
Tinh so e\rc dai va cue tieu nSm tren doan AB.
d.
Diem C va D nam tren mSt
nuac
sao cho ABCD la
hinh
vuong,
tinh
s6 cue dai tren doan CD va AC.

Giai;
=
UB
=
20
cos(207it)
(mm); AB
=
26cm;
v =
50cm/s
Buac
song: X
= vT = v— - SQ— =
10cm
a.
di
= ^2 =>
A
=
2a|cos7r(^2^)|
= 2a =
40mm
b.
di =
21cm;
dz =
26cm
=>
A

=
2a|cos
J(d2
- dJI =
2.20|cos
^(26-21)1
= 0
c.
S6 cue dai:
-^<k<^<^
-2.6 <
fc
< 2,6
A.
A.
—*
CO
5
giz. tri cua —•
5
circ dai.
S6euetilu:^-i<fc<^-i<=>-3.1<fc<2,l
c6
6 gia tri cua k
—*
6
circ
tieu.
d.
ABCD Id

hinh
vuong
=>
CA
=
26V2
vd CB
=
26cm
Xet
CA-CB
26V2-26
=
1,076
A
10
=» diSm
C
nam giua
cue
dai
bae
1
va bac
2.
Do do, s6 c\rc
dai
gifta C va duang trung trye
eua AB la 1, nen:
-

S6
cue dai tren doan CD:
3
- So cue dai tren doan CA:
4
711
CHI/ITNG
Z:
SdNG
cd
VAT
LY
IZ-TOMTAT
lY
THDYgTVA
BAl
TAP TRAC
NCHlgM-TAPI
Bai
tap 3:
Cau
1:
(De thi cao
d5ng nSm 2009)
CJ mat
nu6c
c6
hai
ngu6n song
dao dong theo phuomg vuong

goc
voi
mat
nuac,
c6
cung phuomg
trinh
u
=
Acoscot. Trong mien
gap
nhau cua hai song, nhung diem
ma
a
do cac
phan tu
nuac
dao dong voi bien dp cue dai
se
c6 hi?u duang di cua song tu
hai
nguon den do bang
A.
mot s6 le
\hn
nua
buac
song.
B.
mgt s6 nguyen Ian

buac
song.
C.
mgt so nguyen Ian nua
buac
song.
;
D.
mot so le Ian
buac
song.
Cau
2: (De thi dai h^c nam 2007) DS khao
sat
giao thoa song ca, nguai
ta
b6 tri tren mat
nuac
nam ngang hai ngu6n ket hgp Si
va
Si. Hai ngu6n na)'
dao dong dieu hoa theo phuang thang dung,
ciing
pha. Xem bien
do
song
khong
thay doi trdng qua
trinh
truySn song.

Cac
diem thuoc
mat
nuac
va
nam tren duang trung true cua doan S1S2
se
A.
dao dpng vai bien dp bang nua bien dp cue dai.
B.
dao dpng vai bien dp cue tieu.
C.
dao dpng vai bien dp cue dai.
D.
khong dao dpng.
Cau
3: T^i hai diem A va B tren mat
nuac
c6
2
ngu6n song giong nhau
voi
bien
dp
a,
buac
song
la
10cm.
Diem

M vai MA
=
25cm
va
MB
=
5cm s£
dao dpng vai bien dp
A.
2a. B.
a.
C 2a. D.
0.
Cau
4: Trong thi
nghifm
giao thoa song bai
2
nguon ket
hap
A,
B
tren mat
thoan^
ciia
1
chk
long
dao
dpng theo phuang

trinh
u
=
acos(1007rt) (cm),
van
toe truyen song
v =
0,6m/s. Xet 1
dilm
M c6 hi?u duang di
MA
-
MB
=
3cm.
Tinh
tir
duang trung
tryrc
cua
AB,
dilm
M nam tren
A.
Cue tieu bac 3. B. Cue dai bac
2.
C.
C\rc
tilu
bac 2. D. Cue dai bac

3.
Cau
5
:
6
mat
nuac,
c6 hai nguon ket hpp A, B dao dpng theo phuang than;.'
dumg voi phuang
trinh
=
Ug
= 20cos(l07rt)[mm). Toe
dp
truyen song la
80 cm/s. Coi bien
dp
song khong doi khi song truyen di.
Phan
tu M
a
ma'-
nuac
each
hai ngu6n Ian lupt la
21
cm va 29 cm c6 bien dp dao dpng la
A.
0 mm. B. 40 mm.
C.

30 mm. D. 20 mm.
7A
yAT
It
1Z
-
TiM TAT
lY THUYfT
VA
BAI
TAP
THAC
II8H|£M
-
TAP
1
CHlTKNG
Z:
SdNG
Cd
I
Cau
6:
Trong thi nghi?m
tao
van giao thoa song tren
mat
nuac,
nguai
ta

dung ngu6n
dao
dpng
c6 tan so
100 Hz
va do
dupe
khoang
each
giua hai
ggn
song
lien
tiep nam tren duang n6i hai tam dao dpng
la 4
mm. Van t6c
song tren mat
nuac
la
A.
0,2m/s. B. 0,4m/s.
C.
0,6 m/s. D. 0^8 m/s.
Cau
7 :
Mot nguai lam thi nghiem voi mot chat long va mot chn rung eo
t&i
so 20Hz. Giua hai diem Si, S2 nguai do dim
dupe
12 hypebol quy

tich
cua
cac diem dung yen. Khoang
each
gitta dinh cua hai hypebol ngoai cung
la
22cm.
Toe dp truyen song la
A.
70em/s. B. 80cm/s.
C.
7cm/s. D. 8cm/s.
Cau
8:
(De thi cao dang nSm 2008) Tai hai
diim
M
va
N
trong mot moi
truang truyen song
c6 hai
ngu6n song
ket
hpp cung phuang
va
cung
pha
dao dpng.
Bih

bien dp, van toe cua song khong doi trong qua
trinh
truygn,
tan
so
cua song bang 40 Hz va c6
s\
giao thoa song trong doan
MN.
Trong
dpan
MN,
hai diem dao dpng
c6
bien
dp cue
dai gan nhau
nhk
each
nhau
1,5
em. Van toe truySn song trong moi truang nay bang
A.
2,4 m/s. B. 1,2 m/s.
C.
0,3 m/s. D. 0,6 m/s.
au
9 :
Trong thi nghiem giao thoa tren mat
nuac

gom
2
nguon ket hop iS",,
S2 dao dpng cung pha, cung tin
so
20 Hz. Tai diem M (MSi
=
25 cm, MS2
=
20,5 cm) song
c6
bien dp c\rc dai. Giua M va duang trung tr\rc cua S,
S
2
con
CO
2
cue dai khac. Toe dp truyen song c6 gia
tri
A.
30 cm/s. B. 3 cm/s.
C.
45 cm/s. D. 45 m/s.
Cau
10: Trong thi nghiem giao thoa song tren mat nu6c, hai ngu6n
kk
hgp
A,
B dao dpng vai tin so 20 Hz, cung pha, tai mpt diem M
each

A
va B Ian
luot
la
16cm va 20cm, song c6 bien dp c\rc dai, giiJa M va duang trung true
cua
AB
CO
3 day cue dai khac. Van toe truyen song tren mat
nuac
la
I
A. 20 cm/s B. 26,7 cm/s
C.
40 cm/s D. 53,4 em/s
Cau
11: Tren mat
nuac
nlm ngang, tai hai diem
S,, Sj
each
nhau
8,2
cm,
nguai
ta dat
hai ngu6n song
ca ket
hpp,
dao

dpng dieu
hoa
theo phuang
thang dung
c6
tin
s6
15 Hz va
luon
dao
dpng d6ng
pha.
BiSt
wan
toe
truygn
song tren
mat
nuac
la 30
cm/s,
coi
bien
dp
song khong
d6i khi
truyen
di.
S6
dilm

dao dpng vai bien dp cue dai tren doan SjSj
la
A.
11.
B.8. C.5. D.9.
75
CHtfirH6Z:Stl8Cf WAT it M -
TJM
TAT It
THBYgT
t* BAI TAP TBAC NGRlfM - TAP 1
Cau 12: (De thi cao dfing niin 2010) (5 mat thoang cua
mpt
chat 16ng c6
hai
nguon kk hgp A va
B
dao
dpng
deu h5a cung pha voi nhau va
theo
phuomg
thSng
dung.
Bik
toe
dp
truyen song khong doi trong qua trinh Ian tmyen, bu6c
song do moi ngu6n tren phat ra bling 12 cm. Khoang each ngSn nhlt giiJa hai
dilm dao

dpng
voi bien
dO
cvre
dai
nSm tren doan thSng AB la
A. 9 em. B. 12em.
C.6cm.
D.
3
cm.
Cau 13: (De thi d^i hffc nSm 2009) hai diem A va B each nhau lOem
tren mSt chat long c6 hai ngu6n phat dao
dpng
theo phuong thing diing v6i
cac phuomg trinh la
UA
=
0,5sin(507rt)
cm
;
UB
=
0,5sin(507rt
+ n) cm, v§n t6c
truyen song tren mSt chit long Ik 0,5m/s. Xac dinh s6 diem c6 bien
dp
dao
dOng cure
dai tren doan thSng AB.

A. 12. B. 11. C. 10.
D.9.
Cau 14: Trong
mpt
thi nghi?m giao thoa song tren m5t nuac, c6 hai ngu6n
k6t
hgrp
A va
B
dao
dpng
cung pha voi tin
s6
f = 20Hz, cdch nhau 8cm. Van
t6c truyen
song
tren mat nuac v = 30cm/s. Gpi C va D la hai diem tren
mat
nuae sao cho ABCD la hinh vuong. S6 diem dao
dpng
voi bien
dp
eye dai
tren doan CD
la:
A.
11
diem. B.
5
diem. C. 9 diem. D.

3
diem.
Cau
15:
(De thi dai
hQc
nSm 2010) 6
mat
thoang cua
mpt
chat long c6 hai
nguon song ket hgp A va B each nhau 20cm, dao
dpng
theo phuomg thing
dung voi phuong trinh
UA
= 2cos(407rt) va
UB
= 2cos(407it +
7t)
(UA
vd
UB
tinh
bing
mm, t tinh
bing
s). Biet t6c
dp
truyen song tren mat chat long la

30 cm/s. Xet hinh vuong AMNB thupc
mat
thoang chat
long
So dilm dao
dpng voi bien
dp
c\rc dai tren doan BM la
A. 19. B. 18.
C.20.
D. 17.
^ VANDE4:S6NGDirNG
•
W^t
can
CO
dinh:
Song toi va song phan xa ngupc pha (ngupc
diu).
• Song dung c6
dupe
la do s\ giao thoa cua song tdi va song
phan xa cung phat ra tu
mpt
nguon, tao cac nut va cac bung.
• Khoang each gifta hai niit liSn tiep = khoang each giira hai
b\mg lien tiep =
—
.
V

I J
VAT
It K
-
Till
TAT
li
TIWTfT
VA
BAI
TjP
T«Ac
BGHItM
-
TJP1
CHIMMG
Z:
StNG
Cll
Khoang each giila nut va
bving
lien
tiSp
= —.
Khoang th6i gian giOra hai Ian lien tiep spi day duoi thing la
T/2
Song dung tren sgi day v6i hai
d4u
1^
2 nut

(2
dau c6 djnh):
l
=
n—
2
n=s6bung= (So nut)-1
S6ng dimg tren spi day v6i mpt dau la nut, mpt diu la bvmg
(mpt dau dao dpng t\
do):
n=s6 niit
=
so b^ng
,
X X
l
=
n
2
4
Bai tap mau; Spi day dan hoi AB = 2m c6 dau B c6 djnh, diu A dao
dpng voi tan so lOOHz. Tren day c6 song dimg, diu A xem nhu mpt nut
song. Ngudi ta thay ngoai 2 diu day eo dinh con c6 3 diem khac luon
dumg yen.
a. Tinh van toe truyin s6ng.
b.
Mpt diem M cdeh diu
A
mpt doan
0,75m,

hoi M la nut song hay
b\mgs6ng.
c. Thay doi tin
so
dao dpng or A den gia trj 50Hz tren day van c6
song
dimg,
hoi tren
AB c6
bao nhieu nut song.
Giai:AB = 2m.
. 5 nut
^
4 bung n = 4:1 = 4^
=> X
= Im. v = Xf = 1.100 =
a
lOOm/s
b.
=
2£5
= 1^5
M
\k byng s6ng thii
2
ke tu A.
X/2
1/2
c.
X

= ^ = ^=2m;l = n^=>n =
f
=
2-»2bvng 3nut.
Bai tap 4:
CSu
1: S(?i
day dan hoi AB c6 diu
B
c6 djnh. Dau A dupe rung vdi tin s6 f
tgo mpt song tdi t^ B c6 phuomg trinh Ui = acos(2nft). S6ng phan x? t^i
B
c6
phuong trinh
77
cmm
Z:Sfll«BCtt
yAT LY 12 -
TOM TAT
LY THUVeT VA
BAI TAP TRAC
N6HieM
-
TAP
1
A.
U2
=
acos{2nft
+

n). B.
U2
=
acos(2nft).
C.
U2
=
—asin(2nft). D.
U2
=
asin(2nft).
Cau
2: Sgi day dan hoi AB
c6
chieu dai
/
voi dau
B c6
dinh.
Dau
A
dugc
rung
vai tan
so f
tao mot song toi tai
B
co phuong
trinh
=

acos(2nft).
Song phan xa tai A co phuong
trinh
A.
U2
=
acos (inft
+
B.
U2
=
acos (inft
+
C.
U2
=
-acos {inft
-
D. U2
=
asin (Znft
—
Cau
3:
Dieu
kien
xay
ra song
dung
tren

sgi
day dan
hoi hai
dau
co
dinh
la
A.
Buac song gap doi chieu dai day.
B.
Buac song bang so ban nguyen Ian chieu dai day.
C.
Chieu dai day bang so nguyen Ian
VA
buac
song
.
D.
Chieu dai day bang so nguyen Ian nua
buac
song.
Cau
4: (De thi
tot
nghi^p nam 2007) Khi
c6
song dung tren mpt sgi
day
dan
hoi thi

khoang each giua hai bung song
lien
tiep bSng
A.
mpt phan tu
buac
song. B. mpt
buac
song.
C.
nua
buac
song. D. hai
buac
song.
Cau
5: Quan
sat
song
dimg
tren mot sod day dan
hoi,
nguoi
ta
thay khoang
thai
gian
giiia
2
thai

diem
gan nhat ma day
duoi
thang la 0,2
s,
khoang each
giira
2 cho
luon
dung yen ke nhau la 10
cm.
Toe do truyen song tren day la:
A.25cm/s.
B.lOOcm/s.
C.20
cm/s. D.50 cm/s.
Cau
6: Tren mgt S(?i
day co
chieu dai
/, hai dau co
djnh,
dang
co
song
dung.
Tren day
c6
mgt bung song.
Biet

t6c truyen song tren day
la v
khong
doi.
Tan so cua song la
V
V 2v V
A.—.
B. —. C. —.
D
Cau
7: thi cao d5ng nam 2010) Mpt
sqti
day chiSu dai
i
cSng ngang,
hai
dau co
djnh.
Tren day dang c6 song dung
voi
n
b\mg song, toe dp truyen
song tren day
1^
v.
Kho^g
thai
gian
giiJa

hai Ian
lien
tiep
sgi day
duoi
thing
la
A
V „ nv • ^ ^ ^ ^
A.—.
B.—. C. . D.
n£
£ 2nv nv
71
J
LY 12 -
TdM TAT
lY THUYfT VA
BAI
TAP TRAC
NEHlgM-TAP
1
CHIfdNB
2:
SONG
Cd
Cau
8: (De
thi cao
dang nam 2010) Mpt

sai
day AB
c6
chieu dai
1 m
cang ngang,
dau
A
co
dinh,
dau B gin
voi
mgt nhanh cua am thoa dao dgng
digu
hoa
vai
tan s6 20
Hz. Tren day AB
co
mot song dung 6n
djnh
vai
4
bung
song, B dugc coi la nut song. Toe dp truyen song tren day la
A.
50 m/s. B. 2 cm/s. C. 10 m/s.
D.
2,5 cm/s.
Cau

9: Mgt sgi day dan hoi dai 60 cm rung vai tan
so 50
Hz tren day
tao
thanh
song dung
6n
dinh
vai
4
bung song, hai
dau la 2
nut song. Van
t6c
song tren day la
'
A.
12 cm/s.
B. "60
cm/s.
C.
75 cm/s. D. 15 m/s.
Cau
10: Tren mgt sgi day dan hoi dai 1,8m, hai dau co
dinh,
dang
co
song
dimg
vai

6
bung song.
Biet
song truyen tren day
c6
tan
so
1
OOHz.
Toe
dp
truySn
song tren day la
:
A.20m/s.
B. 600m/s.
C.
60ni/s. D. lOm/s.
Cau
11: (De thi dai hpc n5m 2008)
Trong
thi nghiem
ve
song
dimg,
tren
mpt
sgi day dan hoi dai 1,2m vai hai dau
co
dinh,

ngudi
ta
quan
sat
thay
ngoai
hai dau day co
dinh
con co hai
diem
khac tren
day
khong
dao
dpng.
Biet
khoang
thai
gian
giiia
hai Ian
lien
tiep vai
sgi day
duoi
thang
la
0,05
s.
Van toe truyen song tren day la

A.
8 m/s.
B.
4m/s. C. 12 m/s. D. 16 m/s.
Cau
12: Mgt sgi day
AB
dai 100 cm cang ngang, dau B co
djnh,
dau A gin
voi
mgt nhanh cua am thoa dao dgng dieu hoa vai tan
so 40
Hz. Tren day
AB
CO
mgt song dung on
djnh,
A
dugc coi la nut song. Toe dg truyen song
tren
day la 20 m/s. ca A va
B,
tren day c6
A.
3 nut va 2 bung. B. 7 nut va 6
byng.
C.
9
niit

v^ 8
byng.
D. 5
mit
va 4
byng.
CSu
13: Mgt day
AB
hai diu c6
dinh
AB
=
50cm, v$n t6c truyen song tren
day
Im/s, tan
so
rung tren day
lOOHz.
Diem
M each
A
mpt doan 3,5cm
la
hay b\mg song thu may ke
tir
A:
A.
Nut song thu 8. B. Bung song thur
8.

C.
Nut s6ng
thii
7. D. B\mg song thu
7.
Cfiu
14:
MOt
sgi day AB
= /
m treo
la
lung
bai mgt diu
A
co gin mgt can
v6i
tan
so f
= 40Hz, dau
B
dao dgng t\ do.
Quan
sdt s6ng
dimg
tren
%
c6
5
b6 s6ng, v$n toe truyen song tren day 1^ lOm/s.

Khi
d6 chiSu dai
%
va s6 nut s6ng trSn dSy 1^:
78
CHinMGKStlKCtf
Ul
It 1Z
-
TOM TAT U THBYfT V* BAI TAP
TRAC
MeHlgM
- TAP t
A.
/ = 62,5cm, 6 nut s6ng. B. / = 62,5cm, 5
niit
s6ng.
C.
/ = 68,75cm, 6 nut song. D. / = 68,75cm, 5 nut song.
Cau
15: (De thi dai hgc nam 2011) Mot sgi day dan hoi
cang
ngang, hai
dau
CO
dinh. Tren day c6
song
dung, t6c dp truyen
song
khong

doi.
Khi
tan
s6
song
tren day la 42 Hz thi tren day c6 4 diem b\mg. Neu tren day c6 6
diem
b\mg
thi
tkn
so
song
tren day la
A.
252 Hz. B. 126
Hz.
C.
28 Hz. D. 63 Hz.
A
VAN
BE
5;
S6NGAM
^
^ ^
•
Song am la nhGng son^ ca truySn trong moi trucmg
khi,
long,
ran. Song am c6 cung tan so

voi
ngu6n am.
•
Am
nghe
dugc
c6 tan so tir 16Hz den
20.000Hz
va gay ra cam
giac
am trong tai con nguoi.
•
Ha
am:
Nhihig
song
ca hpc t3n s6
nho
horn
16Hz
ggi
1^
s6ng
ha
am, tai nguoi khong
nghe
dugc.
•
Sieu am:
Nhftng

s6ng
ca hgc tan so
l&n
hem
20.000Hz
goi \h
song
sieu am, tai nguoi khong
nghe
dugc.
•
Nhac am c6 tan so xdc
dinh.
Tap am khong c6 tan so xdc dinh.
•
Song am truyen tot
nhat
trong
chat
rSn, roi den chit 16ng va sau
cung la
chat
khi.
Song am
khong
truyen
dugc
trong
chan
khong.

•
Tin so
s6ng
am khong thay d6i khi truyen qua cdc moi
trudng khdc nhau.
Cvtimg
dO
am (I) t^ mgt diem
1^
d^i
lugng do bSng lugn^ nSng
lugng
ma
song
am tai qua mgt don
vj
dien
tich
d5t
t^i
diem do,
vuong goc v6i phuong truyen
s6ng
trong mgt don vj
thdri
gian.
Don
v}
cuong dg am la W/m^. Cuong dg am ti 1? nghjch voi
binh

phuong kho^g
each
den nguon.
2
Trong
do
dj va
d2
Idn
lu0 la
khoang
each
tic
diim
dang
tinh
cudng
dg
dm
din
nguon.
:
y
Mii-c
cu"6tig
dO
am
(L):
Miic
cuong dg am L la dai lugng de so

sanh
dg to cua am
nghe
dugc
c6 cuong do I voi dg to cua am
chuan
c6 cuong do
IQ.
1(^5) = 10
Ig—
IB
=
lOdB.
DQ
cao cua am: Ph\ thugc vao tan so cua am. Am cao
(hoac
thanh) c6 tSn so
Ion,
am
thap
(hoSc
trSm) c6 tan so nho.
Do to ciua am: Gin
lien
voi
die trung vat ly
miic
cuong dg am.
Am
sac: Giup ta phan bi?t am do cac nguon

khac
nhau
phat
ra.
Am
sic
CO
lien
quan mat
thidt
voi
do thi dao dong am.
Bai
tap 5:
Cau
1: (De thi tot
nghifp
nam
2008)
Mot
song
am truyen tir khong khi
vao
nuoc
thi
A.
tan so va
buoc
s6ng
deu thay doi.

B.
tan so thay
doi,
con
buoc
song
khong thay doi.
C.
tan so khong thay
doi,
con
buoc
song
thay d6i.
D.
tan so va
buoc
song
deu khong thay d6i.
Cau
2: Lugng
nang
lugng
dugc
song
am truyen trong mgt don vj
thoi
gian
qua mgt don
vi

di?n
tich
dat vuong goc
voi
phuong truySn am ggi la:
A.
Cuong dg am. B. Dg to cua am.
C.
Muc cuong dg am. D. NSng lugng am.
Cau
3:
Mgt la
thep
mong, mgt dau c6 dinh, dau con lai
dugc
kich
thich d8
dao dgng
voi
chu
ky
khong
d6i
va
bang
0,08 s.
Am
do
Id
thep

phat
ra la
A.
am ma
tai
nguoi
nghe
dugc. B. sieu am.
C.
h? am. D.
nhac
am.
Cau
4:
Di§u
nao sau day sai
khi
noi
vh
dac trung cua cua am ?
A.
Dg cao cua am phy thugc vdo tin s6 cua am.
B.
Dg to cua am
ph\
thugc vao bien dg hay muc cuong dg am.
CHIfdNG
2:
SONG
Cd

VAT
LY
12
-
TdM
TAT
LY THUYfT VA
BAI TAP
TRAC
WfiHlfM
-
TAP
1
C.
Am sac
ph\ thuQC
vao d^g do
thi cua
am.
D.
Nang lugng ciia song am khong thay doi khi song am truySn di.
Cau 5: Chon cau tra iai sai
•
A. Song am la nhiSng song ca hoc dpc Ian truyen trong moi tnrong
vat chat,
CO
tan s6 tir 16Hz d6n 20.000Hz va gay ra cam giac am
trong tai con nguai.
B.
Song am, song sieu am, song ha am c6 cung ban chat vat ly.

C.
Song am truyen dugc trong mpi moi truong vat chat dan hoi ke
ca chan khong.
D.
Toe do truyen am trong chat r3n thuong Ion hon trong chat long
va trong chat khi.
Cau 6: Khi noi ve song am, phdt bilu n^o sau day la sai?
A. Toe do truyin song am trong khong khi nho hom t6c dp truyen
song am trong nuac.
B.
Song am truyen dugc trong cac moi tnrong rSn, long va khi.
C.
Song am trong khong khi la song dpc.
D.
Song am trong khong khi la song ngang
Cau 7: (De thi tot nghi?p nam 2010) Khi n6i
\h
sieu am, phat bieu nao
sau day sai?
A. Sieu am c6 the truyen dugc trong chit rin.
B.
Sieu am c6 tan so Ion hem 20 kHz.
C.
Sieu am c6 the truyen dugc trong chan khong.
D.
Sieu am c6 the bi phan xa khi gap vat can.
Cau 8: Vai lo la cuong dp am chuan,
11^
cuong dp am. Khi muc cuong dp
am L

=
2 Ben thi:
A.I =
2Io.
B.I=-Io. C.I=10^Io.
D.I=10-2lo
2
Cau 9: Tai dilm
A
c6 muc cudng dp am la 90 dB, biet nguong nghe cua
am do la 16"'^ W/m^. Cuemg dp am
t^ii
A la:
A./^ =0,01 W/ml
B.
= 0,001 W/ml
C.
=
10-' W/ml
D-
=
10"
W/ml
82
VAUy
-
TAT
LY THUYfT VA
BAI TAP TBAC
llBHigM

-
TAP
1
CHIfdNG
2:
SDNG
Cd
CSu 10: Khi muc cuong
dp
am tang 20dB thi cu6fng
dp
am tang:
A.
2
Ian. B. 200 lin. C. 20 lin. D. 100 Ian.
CSu 11: Khi cuong
dp
am tang gap 1000 Ian
thi
muc cuong
dp
am tang
:
A. lOOdB. B.20dB. C.30dB. D. 50 dB.
CSu 12: Nguoi
ta
do dugc muc cuong dp am tai diem
A la
90 dB va tai
dilm B la 70

dB.
Ti
1?
cuemg
dp
am tai A va
B
la.
A
B.30. C.3.
D.
100.
7
Cau 13: (De thi dai hgc nSm 2009) Mpt s6ng am truyen trong khong khi.
Mure cuong dp am tai diem M va tai diem
N lin
lugt 1^ 40 dB
va
80 dB.
Cucmg
dp
am tai N Ion hon cuong
dp
am tai M.
A. 10000 Ik. B. 1000 Ian. C. 40 Ian. D. 2 Ian.
Cau 14: (De thi d^i hpc nSm 2010) Ba diem O, A, B ciong nam tren mpt
nvra
duong thang xuit phat tir O. Tai O dat mpt ngu6n diem phat song am
ding huong ra khong gian, moi truong khong hap th\ am. Mure cuong dp
am tai

A
la 60 dB, tai B la 20 dB. Muc cuong dp am t^i trung diem M cua
doan AB
la
A.26dB.
B. 17dB. C.34dB. D.40dB.
Cau 15: Muc cuong dp am do nguon S gay ra tai diem M la L, khi cho
S
tiSn lai gin M mpt doan 62m thi miic cudng
dp
am tang them 7dB. Khoang
cdch la S den M c6 gia tri xap
xT
la:
A. 210m. B.209m C. 112m D. 42,9m.
CHIfKNG
2:
SANG
CK
V*T LY
1?
- TiM TAT lY THUYf T VA tAl
TAP TBAC MGHltM
-
TAP
1
BAI
TAP
TRAC
NGHIEM

TONG
HQfP
CHl/ONG
2
•
BJNH
NGHIA
S6NG
CO
Cau 1: Chpn cau
dung.
Song
ca
hpc la:
A.
Sir Ian truyen vat
chat
theo
thai gian.
B.
Nhung
dao
dpng
ca hpc Ian
truyen trong
mot
moi truong
vat
chdt
theo

thai gian.
C.
S\
Ian toa vat
chat
trong khong gian.
D.
Sir
Ian truyen bien
dp dao
dong
cua cac
phan
tu vat
chdt
theo
thai
gian
Cau
2: Bu6c
s6ng
X la:
A.
Quang
duang
song
truyen dugrc trong cac chu ki
khac
nhau.
B.

Khoang
each
giiia
hai
diem tren phucmg truyen
song
ma dao
dpng cimg pha voi nhau.
C.
quang duang
song
truyln
dugrc trong mpt dan vi thai gian.
D.
Khoang
each
ngin
nhat
gifta
hai diem tren phucmg truyen
song
ma dao dgng cung pha.
Cau
3: Chon cau dung:
A.
Qua
trinh
truySn
song
la qua

trinh
truyen cac phan tu vat
chat.
B.
Trong qud
trinh
truySn
song
vat
chat
dung yen tai cho.
C.
Qua
trinh
truyen
song
la thay d6i van t6c truyen song.
D.
Qua
trinh
truyen
s6ng
1^
qua
trinh
truyen pha cua dao dpng.
Cau
4: toe
truyln
song

phy thupc
vac
A.
NSng lugmg song. B. Tan
s6
dao dpng.
C.
Moi
truong
truyin
song
D.
Buac
song.
Cau
5: De phan
loai
song
ngang
\h
song
dgc nguoi
ta
dya v^o:
A.
Van toe truyen
song
va
buac
song.

B.
Phucmg truyen
song
va tan
so
song.
C.
Phuomg dao dpng va phucmg truyen song.
D.
Phuomg dao dpng v^ v§n toe truyen song.
VjT LY
12
- TiM TAT
1Y
THDYfl VA
BAI
TAP TBAC
MGHIgM
-
TAP
1
CHtfflHG
Z: SdHG Gfl
Cau
6: Chpn
phat
bieu dung:
A.
TSn
so

song
thay doi khi
song
truyen tir moi truong
nay
sang
moi
truong
khac.
B.
Tan
so
song
duge
xac dinh bai ngu6n
phat
song.
C.
Tan so
song
la
tich
so cua
buac
song
va chu
ki
dao dong cua song.
D.
TSn

s6
song
trong mpi moi truong
dSu
khong
phu
thugc
vao
chu ki dao dong cua song.
Cau 7: Mot nguoi quan
sat mot
chiec
phao
tren
mat
bien thay
no nho len
cao
10
Ian trong 18s, khoang
each
giiJa
2
ngon
song
ke
nhau
la
2m. Van
toe

truySn
song
tren mat biSn la:
A.
Im/s. B. 2m/s.
C.
4m/s. D. 8m/s.
Cau
8: Nguai
ta
nho nhirng giot
nuac
deu
dan xuong mgt diem
O
tren
mat
nuac
phang
lang voi
toe do 80
giot trong mgt phut, thi tren
mat
nuac
xuat
hien nhiing ggm
song
hinh tron tarn
O
each

deu
nhau.Khoang
each
giiJa
4
ggm
song
lien
tiep
la
135cm.T6c dp truyen
song
tren mat
nuac
la
A.
60cm/s. B.45cm/s. C. 350cm/s. D.
360em/s.
Cau
9: Nguoi
ta
gay mot dao dpng
a
dau
O
mot day
cao su de
tao mpt
song
ngang

tren day voi chu ky
1,8s.
Sau 3 giay chuySn dpng truyen
duoc
15m dpc
theo
day. Tim
buoc
song
cua
song
tao thanh truyen tren day.
A.
9m. B. 6,4m. C.4,5m. D. 3,2m.
Cau
10: Mpt nguoi dung
biia
go
manh len duong
ray xe
lua. Cach
cho do
1090m, mpt nguoi
khac
ap
tai xu6ng duong ray,
3 s sau
thi
nghe
thay tieng

go truyen
qua
khong khi. Xac dinh van t6c truyen am trong
thep
duong
ray
cho van toe truyen am trong khong khi la 340m/s:
A.5294m/s. B. 5300km/h.
C.
175,6m/s.
D.
175,6km/h.
QUA
TRINH
TRUYEN
SONG
Cau
11: Cho mpt
song
ngang
c6 phuomg
trinh
song
la:
u
=
8cos
In
.0,1
50j

Trong
do
x
tinh
bang
cm,
t
tinh
bang
giay.
Buac
song
la:
A.
0,1m. B. 50cm. C. 8mm.
D.
Im.
85
CHIMWG
Z:
SPUE
Clt
»AT i* K - TtM TAT It TIWTfT VA BAl TAP
TBAC
IBHlgM - T<P 1
Cau 12: Mpt song ca hpc truySn dpc theo true Ox c6 phuong trinh
u = 2cos (20x
—
2000t)em, trong do x tinh bang m, t ti'nh bang s. Van t6c
cua song la:

A.334m/s. B. lOOm/s. C.314m/s. D. 331m/s
Cau
13:
(De thi tot nghi^p nam 2009) Mot song ngang truySn theo chieu
ngang true Ox, eo phuong trinh song la: u = 6
cos(47rt
- 0,027rx) (u va x
tinh bang cm, t tinh bang s). Song nay eo buoe song la:
A. lOOem. B. 150em. C. 50em.
D.
200em.
Cau 14: Mot song truyen doc theo true x duge mo ta bai phuong trinh:
u = 2cos 2(4nt -
O.Snx
—
^ (cm) trong do x tinh bang met, t tinh
bang giay. Van toe truyen song la
A. 8 m/s.
B.4m/s.
C. 0,5m/s. D.4m/s.
Cau 15: Mot song ca hoc phat ra tir mot ngu6n O Ian truygn tren mat nuoc
van toe 2m/s. Ngudi ta thay hai diem M, N gin nhau nhdt tren mat nuoc
nam tren eung duong thing qua O vd each nhau 40em luon dao dong ngugc
pha nhau. Tan so song do la:
A.0,4Hz. B. l,5Hz. C. 2Hz.
D.
2,5Hz.
Cau 16: Mgt sgi day dan hoi, manh, rat dai, c6 dau O dao dong dieu hoa voi
tan so f theo phuong vuong goc voi sod day. Song tao thanh Ian truySn tren
day voi toe do Idiong doi v = 5m/s. De diem M each O mpt khoang bang 2

cm luon dao dong eung pha voi O thi tan s6 dao dpng nhan gia tri nao trong
eac gia tri sau?
A.40HZ.
B.60HZ.
C. 50Hz.
D.
30Hz.
Cau 17: Mot day dan hoi rit dai c6 dau A dao dong voi tan s6 f theo
phuong vuong goe voi sgi day. Bien do dao dong la a, van t6e truyen song
tren day la 4m/s. Xet diSm M tren day va each A mgt doan 14cm, nguai
U
thay M luon dao dong nguge pha voi A. Bilt tan so f c6 gia tri trong khoang
tir 98Hz den 102Hz. Buoe song cua song do eo gia tri la
A. 4em. B. 6cm C. 8cm D. 5cm.
Cau 18: Dau O cua mgt sgi day dan hoi dao dgng voi phuong trinli
u = 2cos(27it) (cm) tao ra mgt song ngang tren day c6 van t6c v = 20 cm/s.
Mgt diem M tren day each O mgt khoang 2,5 cm dao dgng voi phuong trinh:
88
»AT lY 1Z - TlJM TAT U THUYft VA BAl TAP
THAC
HEHIgM - TAP 1
CKIMNGZ: SdNGCd
A.
UM
= 2eos(2Tct + ^) em. B.
UM
= 2eos(27rt-—) cm.
2 4
C.
UM

= 2cos(27it
+Tc)
em. D.
UM
=2eos27it em.
Cau 19: Song Ian truyen tu ngudn O doc theo 1 duong thing voi bien do
khong doi. CJ thai di^m t = 0, dilm O di qua vi tri can bang theo ehilu
duong. Mgt diem each ngu6n mgt khoang bang 1/4 buoe song c6 li do 5 cm
d thofi dilm bang 1/2 ehu
ki.
Bien dg cua song la
A. lOem.
B.sVJcm.
C.
5
yfl cm.
D.
5cm.
Cau
20:
Mgt song ca hge Ian truySn dgc theo mgt duong thang eo phuong
truyen song tai ngu6n O la:
Ug
= acos (a)t) (cm). Mgt diem M each ngu6n
bang 1/3 buoe song a thai dilm t = 1/2 chu ki c6 do dich chuyin
UM
= 2 em.
Bien do song A la
A.4em.
B.

2 em. C.4/>/3cm.
D.2^/3cm
Cau
21:
Mgt sgi day dan hoi cang ngang. Lam cho dau A cua day dao dgng
theo phuong thing dung voi bien do l,5em va chu ky 0,5s .Luc t = 0, A c6
li do cue dai duong. Song truyen di dgc theo day voi toe dg 3m/s. Coi bien
do song khong d6i. Li dg cua dilm M each A mgt doan 2m tai thai dilm
t= 1,25s la:
A - 0.75cm.
B.
+ 0,75cm. C. -1,5em.
D.
+
1,5em.
Cau
22:
Mgt song ea hgc truyen tir O theo phuong x. Dao dgng tai diem O
CO
dang:
UQ
= 3eos(0,57rt) (cm). Biet li dg ciia dao dgng t^i M a thai dilm t la
3 em. Hay xac dinh li dg cua diem M
sau
thai diem do 6 s.
A. 3em.
B 3cm.
C. 6cm.
D 6
cm.

I'
Cau
23:
Hai diem M, N eung nim tren mgt phuong truyen song each nhau
X/3.
Tai thai diSm
ti
eo
UM
= +3cm va
UN
= -3cm. Tinh bien dg song A?
A.A = 2V3cm.
B.A^SVScm.
||,
C. A = 3 cm. D. A = V6 em.
Cau
24:
Song ca c6 tin s6 40 Hz Ian truyen trong mgt moi truofng voi van
t6c 2 m/s. Hai dilm tren mgt phuong truyen song each nguon song nhiJng
doan Ian lugt 10 cm va 12,5 em, dao dgng
A. vuong pha.
B.
nguge pha.
C.
eimg pha.
D.
l?eh pha
—
rad.

87
CHI/dNG
2:
SONG
Ml
WAT
li n -
IJH
TAT lY
TWTfT
WA lAl
TAP
TRAC
MGHlgM-TAPI
•
GIAO
THOA
SONG
Cau 25: Chpn cau dung nhat: Hai nguon song tren mSt
nuac
thoa dieu kien
ket hop
klii
A.
Cung tan so va eo hieu so pha khong doi.
B.
Cung tan so va eung pha.
C. Cung thn s6 va nguge pha.
D.
Cung tan so va eung bien do.

Cau 26: (De thi dai hoc nam 2007) ^e khao sat giao thoa song ea, nguai ta
bo tri tren mat
nuac
nam ngang hai nguon ket hgrp Si va S2. Hai nguon nay
dao dong dieu hoa theo phuong thang dung,
ciing
pha. Xem bien do song
khong
lhay d6i trong qua
trinh
truyen song. Cac
dikm
thuoc mat
nuac
va
nam tren duong trung true eua doan S1S2 se
A.
dao dong vai bien do bang nua bien dp cue dai.
B.
dao dong vai bien do c\rc tieu.
C. dao dpng vai bien do cue dai.
D.
khong dao dong.
Cau 27: Trong hien tugng giao thoa eua hai song phat ra tu hai
ngu6n
dao
dong nguge pha,vai k la so nguyen va A la
buac
song, nhung diem trong
moi

truong truyen song dao dong vai bien do cue tieu khi hieu duong di cua
hai
song thoa
A.
(2k +
l)
B. (2k +
l)>
C.
(k+-)
D.kX.
Cau 28: Ky hieu X la
buac
song, di-d2 la hi?u khoang cdch tir diem M din
cac
ngu6n
song ket hgp Si va S2 trong mgt moi truong
d6ng
tinh.
k = 0, ± 1;
±
2, Diem M se luon luon dao dong vai bien do cue dai neu
A.
di - d2 = (2k + 1)
X,^
neu 2
ngu6n
dao dpng nguge pha nhau.
B.
di - d2 = kX, neu 2 nguon dao dpng cimg pha nhau.

C. di - d2 = X-^ neu 2 nguon dao dpng nguge pha nhau.
D.
di -
d2
= (k + 0,5) X , neu hai nguon dao dpng vuong pha pha nhau.
Cau 29: Tai hai diem A va B trong mot moi truong truyen song c6 hai
nguon song ket hgp, dao dpng eung phuong vai phuomg
trinh
ihn lugt la
u^
=
acoscot
va Ug = acos(cot +7t). Biet van toe va bien dp song do moi
88
MAT
LY 1? - TtM TAT lY
THUYfT
VA BAI TAP TBAC
HGHIgM
- TAP 1
CHIfdNB
2:
SdNG
Cd
ngu6n tao ra khong d6i trong qua
trinh
song truygn. Trong khoang giua A
va B
CO
giao thoa song do hai nguon tren gay ra.

Phan
tii vat chSt tai trung
dikm
eua doan AB dao dpng vai bien dp bang
1
A. 0. B.a/2. , C.a. D.2a.
Cau
30: Hai nguon kk hgp A va B giong nhau tren mat thoang chdt long
dao dpng vai tan so 8Hz va bien dp a = 1mm. Bo qua s\ mk mat nang
lugng
khi
truy§n
song, van toe truyen song tren mat thoang la 12 cm/s.
Digm
M nam tren mat thoang
each
A va B nhimg khoang
AM=17,0cm,
BM
=
16,25cm dao dpng vai bien dp
A.
0cm. B. 2em. Clem.
D.l,5cm.
Cau
31: (De thi cao dSng nam 2009) CJ mat
nuac
c6 hai nguon song dao
dpng theo phuong vuong goc vai mat
nuac,

c6 cung phuong
trinh
u =
Acos(cot).
Trong mien gap nhau cua hai song, nhijng diem ma a do cac phan
tijr
nuac
dao dpng vai bien dp c\rc dai sS c6 hi?u duong di eiia song tir hai
nguon den do bang
A.
mot so le Ian nua
buac
song.
B.
mot s6 nguyen Ian
buac
song.
C. mpt so nguyen Ian nua
buac
song,
D.
mpt so le Ian
buac
song,
Cau
32: Tai hai
dilm
A va B tren mat
nuac
c6 2 ngu6n song nguge pha,

cung bien dp a,
buac
song la 10cm, Coi bien dp khong doi khi truyen di.
Diem
M
each
A 25cm,
each
B 35cm sS dao dpng vai bien dp bang
A.
a. B.2a. C. 1,5a. D. 0.
Cau
33: Trong mpt thi nghiem ve giao thoa song tren mat
nuac,
2 nguon ket
hop Si va S2 dao dpng cung 15Hz. Van t6c truyen song tren m|t
nuac
la
30cm/s. Vai diem M eo nhung khoang di va d2 nao duoi day se dao dpng
vai
bien dp cue dai?
A.
di = 25cm va d2 = 20cm, B. di = 25cm va d2 = 21cm.
l^PI' C. di = 25cm va d2 = 22cm, D. di = 20em va d2 = 25cm,
Cau
34: Th\rc hi?n giao thoa song ca hpc vol 2 ngu6n ket hgp Si va S2 dao
dong cimg pha va cung bien dp 1cm,
buac
song
A.

^ 20em. Hoi nguon M
each
2 ngu6n Si va S2 cac khoang 50cm va 100cm se dao dpng vai bien dp
A.
0 B. V2cm C. cm
D.
2cm
2
89
CHIfdHG
Z: 50IIB Cd VAT lY « -
TlJM
TAT it
THBYgT
Mk
BAI TjP TRAC
MHlgH
- TAP 1
Cau 35: (De thi dai hoc nam 2009)
Dieu
ki?n
dk hai song ca khi gap nhau,
giao thoa dugc vai nhau la hai song phai xuat phat
tir
hai
ngu6n dao dong
A.
cung bien do va c6 hieu s6 pha khong doi theo thai gian.
B.
cung tan so, cung phuong.

C.
CO
cung pha ban dau va cung bien do.
D.
cung tan so, cung phuang va c6 hi?u so pha khong doi theo
thai
gian.
Cau 36: De hai song ket hgrp giao thoa cung pha
tri?t
tieu
nhau thi chung
phai
c6:
A.
Cung
bien
do,
hieu
duong
di
bSng mot so nguyen
Ian
nua
buac
song.
B.
Cung bien do va
hieu
duong
di

bang mot so le Ian nira
buac
song.
C.
Hieu
duong di bing mot so nguyen ihn
buac
song.
D.
Hi$u
duong di bSng mpt so ban nguyen Ian
buac
song.
Cau 37:
Phat
bieu nao sau day la khong dung?
A.
Khi xay ra hien tugmg giao thoa song tren mat chat
long,
ton tai
cac diem dao dong vai bien dp cue dai.
B.
Khi xay ra hien tugng giao thoa song tren mat chat
long,
ton tai
cac
dilm
khong dao dong.
C.
Khi xay ra hien tucmg giao thoa song tren mat chat

long,
cac
diem
khong dao dong tao thanh cac van cue
tieu.
D.
Khi xay ra hi^n thugng giao thoa song tren mat chat
long,
cac
diem
dao dong manh tao thanh cac duong
thing
cue dai.
Cau 38: Trong hi?n
tugntig
giao thoa song tren mat nuac, khoang
each
giiJa
hai
cue dai
lien
tiep nam tren duong noi hai tarn song bing
A.
Bang hai Ian buoc song.
B.
Bang mot buoc song.
C.
Bang mpt nua buoc song.
D.
Bang mot phan tu buoc song.

Cau 39: Mpt sgd day cao su cang
thing
nim ngang c6 dhu A noi vai mot
ban rung c6 tan so f = 0,5Hz .Sau 2s dao dong truyen di dugc 10m, hoi tai
diem
M tren day
each
A mgt doan 5m c6 trang thai dao dpng so voi A la:
A.
Ngugc pha. B. Cung pha.
C.
L?chpha
—
rad.
D.
Lfchpha
—
rad.
VAT
LY 12 - TdM TAT lY
THPYgT
WA
BAI
TAP THAC
WSHIgM
- TAP 1
CHlAfNG
Z: SdllG I
Cau 40: (Cao ding 2007) Tren mat
nuac

nim ngang, tai 2 diem Si va S2
each
nhau 8,2cm, nguoi ta dat 2 nguon song ca ket hgp, dao dgng dieu hoa
theo phuang
thing
dung c6 tan so 15Hz va
luon
dao dong d6ng pha.
Biet
van
t6c truySn song tren mat nuoc la 30cm/s, coi bien do song khong d6i khi
truySn
di.
S6 diem dao dgng
voi
bien dp c\rc dai tren doan S1S2 la:
A.
9. B. 11. C. 8.
D.
5.
Cau
41:
Dung mot am thoa tao ra tai hai diem Si, S2 tren mat nuoc hai ngu6n
song cung bien dp, ngu-gc pha. Khoang
each
giiia
nguon Si,
S2
la 16,4cm. Kit
qua tao ra

nhilng
ggn song dang hyperbol, khoang
each
ngin
nhk giCra hai
ggn
loi
lien
tiep
la
2cm.
So ggn
loi
va lom
xuit
hien
giiia
hai
dilm
S1S2 la
A.8va9.
B.9val0. C. 14val5. D. 8va7.
Cau 42: 6 mat nuoc c6 hai nguon song co A va B
each
nhau 15 cm, dao
dong dieu hoa
ciing
tan so, cung pha theo phuong vuong goc vai mat nuoc.
Diem
M nam tren

AB,
each
trung dikm O la
1
cm, la diem gin O nhat
luon
dao dong voi bien dp c\rc dai. Tren duong
tron
tam O, duong
kinh
10cm,
nim
0 mat nuoc c6 so diem
luon
dao dong
voi
bien dp cue dai la
A.
18. B. 16. C.20. D. 17.
Cau 43: Trong thi nghi^m giao thoa song tren mat nuoc, hai ngu6n
AB
each
nhau 18cm dao dong cung pha.
Diem
M tren AB gan trung diem I cua AB
nhat,
each
I la 2cm
luon
dao dong c\rc dai. So diem dao dpng cue dai tren

duong
elfp
thupc mat nuoc nhan
A,
B lam
tieu
diem la
A.
20. B. 18. C.28. D. 14.
Cau 44: Tai hai diem tren mat nuoc, c6 hai ngu6n phat song A va B c6
phuong
trinh
u=acos(40Tct) (cm), van t6c
truyln
song la 50 cm/s, A va B
each
nhau 11cm. Gpi M la diem tren mat nuoc c6 MA =10 cm va
MB=5
jliCm.
So diem dao dpng c\rc dai tren do^
AM
la
A.
9. B. 7. C. 2. D. 6.
Cau 45: Tai hai
dilm
A, B tren mat nuoc c6 hai ngubn dao dpng cung pha
va
cung tan so f = 12Hz. Tai diem M
each

cac nguon A, B nhung doan di =
18cm,
d2 = 24cm song c6 bien dp c\rc dai. Giua M va duong trung true cua
AB
CO
hai duong van dao dpng voi bien dp c\rc d^i. Van t6c truySn song
tren
mat nude bing bao nhieu?
A.24cm/s.
B.26cm/s. C.28cmys. D.20cm/s.
9ll
CHIiQNB
t.
SONG
Cd
VAT It « - TJH TAT
lY
THMYgT
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BAl
TAP TRAC
II6HI£III
- TAP
1
Cau 46: Tai hai diSm A va B tren mSt
nuac
c6 hai ngu6n ket hop cung dao
dong
vori
phuong

trinh:
u =
acos(100;rt)
(cm). Van toe tniyen
song
tren mat
nuac
la V = 40 cm/s. Xet
dilm
M
tren mat
nuae
eo
AM
= 9 cm va
BM
= 7 cm.
Hai
dao dong
tai
M
do hai
song
tir
A
va
B
truyen den
la
hai

dao dong
A.
cung pha. B. ngugrc pha.
C. vuongpha.
D.
lech pha 2rr/3.
Cau
47:
6
mat
ehdt
long
c6
hai nguon
song
A,
B
each
nhau
18
cm,
dao
dong
theo
phuorng thing dung vai phuong
trinh
la
=UB
=acos(507rt)
(vai

t
tinh
bang
s). T6c do truySn
song
a
mat
chat
long la 50 em/s. Goi O la
trung diem eua
AB,
diem M
a
mat
chk
long nam tren
duang
trung true cua
AB
va gan O nhdt
sao
cho phSn tu
chat
long tai M dao dong cung pha vai
phan tu
chat
long tai O. Khoang
each
MO
la

A.
2 cm. B. 10
cm.
C. l^l
em. D.
2710 cm.
•
SONGDlTNG
Cau
48:
Chpn ket luan sai
khi
noi ve s\ phan xa cua
song
A.
Song phan
xa
luon luon
c6
cung van
t6c
truyen vai
song
tai
nhung
ngugre
huomg.
B.
Song phan xa luon luon cung pha vai
song

tai.
C. Song phan xa c6 cung tin so vai
song
tai.
D.
Sir phan xa a dau c6 dinh lam doi ddu
phuang
trinh
song.
Cau
49:
Song dung
duac
hinh thanh bai:
A.
Sir giao thoa cua hai
song
ket hgrp
B.
S\ giao thoa cua mot
song
tai va mpt
song
phan xa cua no cung
truyen
theo
mot phuong.
C.
Sir t6ng
hgrp

trong khong gian
ciia
hai hay nhieu
s6ng
ket hap.
D.
Sir
t6ng
hgrp
cua hai
song
toi
va
song
phan truyen
khac
phucmg.
Cau 50: Chgn cau dung.
Khi
c6
song
dung tren day dan h6i thi
A.
tat ca cac
dikm
tren day deu dimg
lai
khong dao dong.
B.
nguon

phat
song
ngimg
dao dgng
con
cac
diem
tren day
van
dao dgng.
C.
tren day c6 cac diem dao dgng manh xen ke
voi
cac diem dung yen.
D.
tren day chi con
song
phdn x?, con
s6ng
tai bj
trigt
tieu.
WAT
LY
n
-
Tiw
TAT
li
mi€j

vA
BAI
TAP TBAC
IIEHIEM
- IAP I
CHKIAIG
2: SiNG Cd
Cau
51:
Mot day dan dai 60cm
phat
ra
mot am
c6
tin
s6
lOHz. Quan
sat
song
dimg tren day nguai ta thay c6 4 nut g6m ca 2 nut
a
2 dau day.Van t6c
truyen tren day la:
A.
4cm/s. B.40cm/s. C.4m/s. D.6m/s.
Cau
52:
Mgt sgd day dan hoi dai 50 cm c6 hai dau c6 dinh, dao dong duy
tri
vai

tan so f= 5 Hz, tren day c6
song
dimg on dinh vai 5 byng song. Van toe
truyen
song
tren day
bang
A.
0,4 m/s.
B.
2 m/s.
C.
0,5 m/s. D.
1
m/s.
Cau
53:
(De
thi
cao dSng nam
2009)
Tren mgt sgd day dan h6i dai 1,2 m,
hai dau
c6
dinh,
dang
c6
song
dung.
Bik

song
truyen tren
day c6 tan so
lOOHz
va toe dg 80m/s. So b\mg
song
tren day la:
A.
3 B. 5
C.4
D.
2
Cau
54:
Day
AB
cang
nam
ngang
dai 2m, hai dau A va B c6 dinh, tao mot
song
dung tren day vai tin so 50Hz, tren doan
AB
thay c6 5 nut song. Van
toe truyen
song
tren day la:
A.
lOOm/s. B. 50m/s. C.25m/s. D. 12,5m/s.
Cau

55:
Mgt day
AB
dai 100cm c6 diu B c6 dinh. Tai dau A th\rc hien mot
dao dgng dieu hoa c6 tan s6
f
=
40Hz. V$n toe truyen
song
tren day la v
=
20m/s. So diem nut, s6 diem b\mg tren day la bao
nhieu?
A.
3 nut, 4
bving.
B. 5 nut, 4 byng.
C.
6 nut, 4
b\ing.
D.
7 nut, 5 b\mg.
Cau
56:
Mgt sgi day dan hoi
AB
hai dau c6 djnh.
Khi
day rung voi tan s6
f

thl
tren day c6
4
bo song. Khi tan
so
tang them lOHz thi tren day c6
5 bo
song, v§n tpc truyen
song
tren day
la
lOm/s. Chieu dai va tan
s6
rung cua
day la:
A.l
= 50cm,f=40Hz.
B.
l
= 40cm, f= 50Hz.
C.
1
= 5cm,
f
=
50Hz. D.
1
= 50cm,
f
=

50Hz.
Cau
57:
V^n
t6c truyen
song
tren mgt sgd day la 40m/s.Hai dau day c6 dinh.
Khi
tin
so
song
tren day 200Hz, tren day hmh thanh
song
dung vai
10
bvmg
song.Tin so nao cho duod day
ciing
tao ra
song
dimg tren day:
A.90HZ.
B.70HZ.
C.60Hz.
D.
llOHz.
I
CHlflMG
t.
SdNG

Cd
Hi It
12
-
Tim TAT
LY THUYfr vA
BAI TAP TBAC
HGHI£M-TAPI
Cau
58:
Mot day AB dai 1,80m cSng thing nim ngang, dau B c6 djnh, dau
A gin vao mpt ban rung tan so lOOHz. Khi ban rung boat dpng, nguoi
ta
thay tren day c6 song dimg g6m
6
bo song, voi
A
xem nhu mpt nut. Tfnh
buac song va van toe truyen song tren day AB.
A.X
=
0,60m; v = 30m/s. B.
X
= 0,30m; v = 60m/s.
C.
A,
= 0,60m; v = 60m/s. Dl=l ,20m; v = 120m/s.
Cau
59:
Mpt sgi day manh AB dai 1,2m khong gian, dau B c6 dinh, diu A

dao dong voi f = lOOHz va xem nhu mot nut, t6c do truy6n song tren day la
40m/s,
bien dp dao dong la
1,5cm.
S6 b\mg va be rpng cua mpt biing song
la
A. 7 bung, 3cm. B. 6b\mg, 3cm.
C.
7bung,
1,5cm.
D. 6 b\ing, 6cm.
Cau
60:
Quan sat song dimg tren sgi day AB, dau A dao dpng diSu hoa theo
phuomg vuong goc voi soi day (coi A la
nut).
Voi dau B t\ do va tan so dao
dong cua dhu
A
la 22 Hz thi tren day c6 6 nut. NIU dau B c6 dinh va coi toe
do truyen song tren day nhu cu, de van c6 6 nut thi tan s6 dao dong cua diu
A phai bang
A. 25 Hz. B. 18Hz. C.20Hz. D. 23 Hz.
Cau
61:
S6ng dimg tren
mpt
sgi day dan hoi c6
bieu thuc:
M

=
2cos(—)cos(20;r/+^„)(c/?j).
Trong do
u la
U dg tai thai diem
t
cua
4
mgt phan tu M tren day m^ vi tri can
bang
cua no each goc O mgt doan la x
(X do b3ng cm;
t
do bSng
s).
Van t6c truyen song tren day
A. 80 cm/s. B. 40 cm/s.
C.
160 cm/s.
D.
100 cm/s.
Cau
62:
Mgt sgi day AB
=
60cm voi dau B c6 djnh. Ddu
A
dao dgng vai
tan so 50Hz thi tren day c6 12 b6 song nguyen va A xem nhu mgt nut song.
Neu A la nut song thu nhat, diem N each A mgt do^ 20cm la

A. nut s6ng thu
5.
B. bung s6ng thu 5.
C.
nut song thii
4.
D. b\mg song thu 4.
Cau
63:
(De thi dai hpc nSni 2011) Mgt sgi day dan hoi cang ngang, dang
CO
song dimg 6n dinh. Tren day, A la m^t diem niit, B la mgt diem b\mg gan
A nhat,
C
la
trung diem ciia AB, vai AB
=
10 cm. Biet khoang thai gian
ngSn nhdt giOa hai Ian m^ li dg dao dgng cua phan
tijr
tai B bing bien do dao
dgng cua phSn tu t^ Cl^ 0,2 s. T6C dg truyen s6ng tren day la
A. 0,25 m/s. B.
2
m/s. C. 0,5 m/s.
D.
1 m/s.
If
AT
LY 1Z

-
TiM TAT
lY
THBYgl
VA BAI TAP
TBAC
BBHlgM
-
TAP
1
CHI/tfNG
Z: StNG
Gd
• SONG AM
Cau
64:
Dilu nao sau day la sai khi noi ve song am?
A. Song am
la
song ca hgc dgc truyen dugc trong moi trucmg vat
chat ke ca chan khong.
B.
Song am c6 tan s6
nim
trong khoang tir 16Hz den 20.000Hz.
C. Song am khong truyen dugfc trong chan khong.
D.
Van toe truyen am ph\ thugc nhift
dg.
,

Cau
65:
Chgn cau dung. Am sSc
1^
dSc tinh sinh ly cua am dugc hinh thanh
dira tren dac tinh vat ly cua am la:
A. Bien
dg.
B. Tan so.
C.
Nang lugng am. D. D6 thj dao dgng am.
Cau
66:
Chgn cau dung. Dg cao cua am phu thugc vao:
A. Bien dg. B. Tan s6.
C.
Nang lugfng am. D. Van t6c truySn am
Cau
67:
Chgn cau dung. Dg to cua am ph\ thugc vao:
A. Tan so va bien dg am.
B.
Tan s6 am va miic cuang dg am.
C. Buac s6ng va nang lugmg am.
D.
V$n toe truyen am
Cau
68:
Am thanli truyen nhanh nhat trong moi truang nao sau day?
A. Khong khi. B.Nuac. C. Sat. D.Khihidro.

Cau
69:
Phat
hiku nho
sau day
1^
dung nhSt ?
A. Am
CO
cuang dg Ian thi tai ta c6 cam giac am do "to".
B.
Am c6 cuang dg nh6 thi tai ta c6 cam giac am do "be".
C.
Am
CO
tan s6 Ian thi tai ta c6
c^
gidc am do "to".
D.
Am
"to"
hay
"nh6"
ph\ thugc vko muc cuang dg am va tan
so
am.
Cau
70:
(De thi d^i hgc nam 2008) Mgt
la

thep mong, mgt dkn
c6
dinh,
con
l^i
dugc kich thich
de
dao dgng v6i chu ki khong doi va bang
0,08 s. Ani do
Id
thep phat ra
Ik
A. Sieuam. B.Haam.
*
C.
Nhac am. D. Am ma tai nguai nghe dugc.
CHKdNG
2:
SdNG
CO
«AT
LV 12 -
T6M
TAT LY THUYft «A BAl
TAP
TRAC
IISHigM
-
TAP
1

Cau
71:
(De thi cao
ding
nhm
2009)
Khi
song
am
truySn
tir moi
truomg
khong khi vao moi truong nuac thi
A. chu ki cua no tSng.
B.
tan so cua no khong thay doi.
C.
buoc song cua no giam.
D.
buoc song cua no khong thay d6i.
Cau
72:
Song
ca
hpc Ian truyen trong khong khi khi cuong do
du
lom,
tai
ta
CO

the cam th\ duac song
ca
hoc nao sau day:
A. Song
CO
tan
s6
lOHz.
B.
Song c6 tan
s6
30kHz.
C.
Song
CO
chu ky 2 // s. D. Song c6 chu ky 2ms.
Cau
73:
(De thi cao
ding nSm 2010)
Khi noi ve
song
am,
phat bieu nao
sau day la sai?
A.
d
Cling
mpt
nhi?t

dp, toe dp
truySn song
am
trong khong
khi
nho hon
t6c
dp truyen song
am
trong nuae.
B.
Song
am
truyen dupe trong
cac
moi truong rin, long
va
khi,
C.
Song am trong khong khi
la
song dpc.
D.
Song
am
trong khong khi la song ngang.
Cau
74:
Mpt
nguoi dung truae each ngu6n

am
S mpt
doan
d.
Nguon nay
phat song cau. Khi nguoi do di
lai gin
ngu6n
am
50m thi thay cucmg dp
am
tang len
gdp
doi. Khoang each
d
la:
A.
«222m.
B.
«22,5m.
C. «
29,3m.
D.
«171m.
Cau
75:
Mpt nguon diSm O phat song
am
c6 cong suat khong doi trong
moi

moi truomg truyen
am
dang huong
va
khong hap
thu
am.
Hai
diem
A, F
each nguon
am
Ian lupt
la
ri
va
ra.
Biet cuong
dp
am
tai
A
gap
4
Ian cuon;
dp am
tai B. Ti s6 so vai ri la:
A. 4.
B.2. C. 1/2.
D.1/4.

Cau
76:
d
khoang each
di
= 1000m tnrac
mpt
ehigc
loa,
miic cuong
d
am
la Li=
lOdB. Tinh cucmg
dp
am
I2
tai
diem
nam
each
loa mpt
khoang
da
=
10m.
Bik
song do loa phat
ra
Ian toa trong khong gian dual dang soir.

eiu. Cho
hik
cuong dp
am
chuan la
IQ
=
10"'^wW.
A.70W/m2.
B.
10-'W/m2.
C.
lO'^W/m^.
D.
lO'^W/ml
tf AT Lt 12 - Tim TAT
LY
iHcygT
vA BAI T^P TBAC
wemgH
-
TAP
1
CHIftfNG
2:
SiNG
CB
Cau
77:
Nguon

am
S phat
ra
mot am c6 cong suit P khong doi, truySn ding
huong
\h
mpi phuomg. Tai dilm
A
each S mpt doan
rA
=
Im, muc cuong
dp
am la
70dB.
Gia su moi
truong khong
hap
thvi
am.
Mure cuong
dp am tai
diSm B each nguon mpt doan
TB
=
lOm la:
A. 30dB.
B.
90dB. C. 50dB. D. 60dB.
Cau

78:
Mue
cuong
dp am tai hai
diSm
A,B
Ian
luprt
la: 30 dB va 20 dB.
Suy ra lien he giiia cucmg dp am tai A va tai B
la:
A.
IA = 6 IB/5. B. IA = 5IB.
C.
IA
=
IBVIO.
D. IA=10IB.
Cau
79:
Khi
song
am
truyen
tir moi
truong khong
khi v^o m6i
truong
nuoc
thi

A. chu ki cua no tSng.
B.
tan
so cua no khong thay d6i.
C.
buoe song cua no giam.
D.
bu6e s6ng cua no khong thay doi.
Cau
80:
Khi noi v^ song am, phdt bilu nao sau day la sai?
A.
O
cimg
mpt
nhi?t
dp, toe dp
truyen song
am
trong khong
khi
nho
horn
t6e dp truySn s6ng am trong nuoc.
B.
Song am truyen dupe trong cac moi truong rSn, long va khi.
C.
Song am trong khong khi la song doe.
D.
Song am trong khong khi la song ngang.

97
CHinrNG
2:
SfiNG
C0
MAT It
1Z -
TlJM
TAT
LY THBYfT VA
BAl TAP
TRAC
I»6HI€M-TAP1
DAP
AN
CHirONG
II
Bai tap
1:
Dinh nghta song
cor
Can 1 2 3 4 5 6 7 8 9 10
Dap
an
C B B B C A B B C A
Cau
5:
/ = I
=
^

=
50Hz
A.
I '
Can
6:
6A
=
3cm
A
=
0,5cm;
v
=
Xf
= 0,5.100
=
50cm/s
Cau
7:
A
=
2m; 57
=
8
r =
1,6s; v
= ^ =
^
=

l,25m/s
Cau
8:
/ =
120//z; 4A
=
0,5
A
=
0,125m;
v
=
A/
=
0,125.120
=
15m/s
Cau
9:
^
=
^
=
^
=
4,4 -> tang 4,4 Wn.
Ai
Vi 330
Cau
10:r =

^
=
i^
=
0,ls;^
=
-^
= -^ = 20
w
2071 ''AT- 0,1
BM tap
2; Qu^
trinh truyen song - 3$ l^ch pha - phirong
trinh
truyen s6ng
Cau 1 2 3 4 5 6 7 8 9 10
B^p dn D A B A B B C A
c
Cau 11 12 13 14 15
D^p ^n C C B C D
-
1 V 360 „ _ A
27rx 27r0,2
TT
^«"2:A
= -
=
-
=
0,8m;

=
—
=
— =-
Cau 3: A(p
=
2Ttx
27r.4S
37r
A
60 2 '
sdn^
t<zi M
do
nguSn
0
truyin
tai
luon chgm
pha
han
0
Cau
4:
A
= - :™ =
0,6^n;
A<p
= —
VAT

LY 12 -
TIJM
TAT LY THUYET VA BAI TAP TRAC
HEHIgM
- TAP 1
CHI/lfNG2:
SdNGCd
n
2nx
0,6
=>
X -
0,1m
Cau 5:
A
= vr =
1.2
=
2m; A(p
= ^
TT
= ^
=>
;c
=
Im
Cau
6:
= —
=*

-
=
—
=»
A
=
4m; f
=
1250//z
^„
_ . 2nx , n , ,
2nfx
, 2fx X
Cau 7: A(p = — =^ - +
fcjT
= —^ =^ k = —— -
A.
£t
Vi22 <f<2e
fcGZ
nen 2,58
< <
3,14
=>
fc
= 3
->
A
=
16cm

Cau 8: ^(p
=
2nx
n
+
kin =
2nfx
k=tl-l
V
2
.
Vi
0,7
< v < 1
kG2
nenl,5
<
fc
<
2,35
fc =
2 ->
v
=
80cm/s
Cau9:uM
=
5cos[7r(^-g
=
0

Cau 10:
^ = ^
A
=
3m;
v
=
A/
=
A ^
=
0,5m/s
Cau
11:
^ =
0,027r:c =>
A
=
100cm
2nx
Cau
12:
^ =
0,02;!^:
A
=
100cm; v
=
A/
=

A —
=
200cm/s
2n
Cau
13:
A
=
7
=
^
=
5cm;
x =
33,5
-
31
=
2,5cm;
J
80
Inx
In.
2,5
=
n
Cau
14:
A
=

vT
= =
24^
=
9,6cm;
2l
(^ 2nx\ n\
UM
=
5cos\5nt
-
—j
=
5cos[5nt j(cm)
Cau 15: X
=
vT
=
v—=
10-
=
20m;
UM
=
2cos
TTt-
n
2nx
5o+-
j

=
2
cos(7rt)
(cni)
CHI/dNG
Z: ^dNG Cd
VAT
LY
IZ-TfiMTAT
LY THUYfT VA
BAI TAP TRAC
MHlgM-TAPl
Bai
tap 3; Giao thoa
song
Cau
1
2
3
4
5
6
7
8
9 10
Dap
an
B
C
A A A

D
B B
A A
Cau
11
12
13 14 15
Dap
an
D
C C
B
A
Cau
3: .4
=
2a|cos [7i(^^)]|
=
2a|cos
= 2a
Cau
4:
A
= =
v
—
=
0,6
— =
0,012m

=
1,2cm;
6J
IOOTT
d2
-
di
3
3
~ " 1~9 ~ ^'^ ^
Cau
5:
A
= =
v—
=
80—
=
16cm;
A
= 2a|cos [%
(6.2
-
di\
]|
=
2.201
cos
[71
/29

-
21\
.
16 >
=
0
Cau
6:
- =
4mm =^
A
=
8mm;
17
=
A/
=
8.100
=
800mm/s
=
80cm/5
Cau
7: 11 ^
=
22cm =>
A
=
4cm;
v = Xf =

4.20
=
80cm/s
Cau
8:
- =
1,5cm
A
=
3cm;
v
= Xf =
3.40
=
120cm/s
=
l,2m/s
Cau
9:
d2
-
di
=
3A
A
= =
1,5cm;
•5
i;
=

A/
=
1,5.20
=
30cm/s
Cau
10:
d2 -
di
=
4A =»
A
= =
1cm;
V =
A/
=
1.20
=
20cm/s
Cau
11:
A
= 7 = =
2cm;
-S^S2
<kX<
S^Sz
J
15

=>
-4,1
<
fc
<
4,1
—>
cd 9 gid
trf k 9CD
yAT
LY IZ -
TfiM
TAT LY THUYfT
VA BAl
TAP
TBAC
weHieni
- TAP 1
CHI/dNG
Z:
SUNG
Cd
Cau
12:
i = Y =
6cm
Cau
13: Hai nguon dao dong ngugc pha
Buac song: X
= vT = v—

=
SO^=
2cm;
^
cj son
So cue dai:
-SiS2<(k
+
^X<S^S2
=>
-5,5
<
fc
<
4,5
—>
cd 10
gid tri
lOCD
Cau
14:
A
= y = ^ =
1,5cm
Xet:
CA-CB
8V2-8
=
2,2
C

ndm giua cue dai bgc 2 va
3
A
1,5
So cue dai tren doan
CD:
2.2
+ 1 = 5
(ke ca cue dai bae 0)
Cau
15: Hai nguon dao dpng
nguae
pha;
2n
In
X
= vT =
v—=30-—= 1,5cm
S6 cue dai tren doan
AB:
/
1\
-5iS2
<• k+-
A
<
5i52
\/
=>
-13,8

<
fc
<
12,8
—>
cd 26
gid tri
fc->
26Cf)
So cue dai tren doan BO (O la trung diem eua
AB):
y = 13
Xet:
MB-MA
20V2-2O
=
5,52
—»
M ndm
giica
CD bgc 6vd7
A
1,5
S6 cue dai tu M den duong trung true cua
AB:
6
S6 cue dai tren doan
MB:
6 +
13

= 19
Bai
tap 4:
Cau
1
2
3
4
5
6
7 8 9
10
Dap
an
A
C
D
C
D
A
D
C
D
c
Cau
11
12
13
14
15

Dap
an
A
D
C
A
D
101
CHirdNG
2:
StNG
Cd
VAT LY
T2-TliMTAT
ij
THBTgT
VA
BAl
TAP TBAC
WSHlgM
- TAP
i
Cau 1: Vat can c6 dinh => song phan xa ngugc pha (ngugc diu) vai
song tai vat can:
U2
= acos (2nft +
n)
Cau
2:
Song phan xa tai B:

=
-acos(2nft)
Song phan xa tir B truyen den
A:
=
-acos(2nft
- ^)
Cau 5:
^
=
0,2
r =
0,4s; ^
=
10cm
A
=
20cm;
V
=
4
=
50
cm/s
Cau 6:1 hung song ->/
=
l.^
=
^=»/
=

J
Cau 7: i=n-
= n >T = >- = —
2
2 nv 2 nv
Cau 8:
4
bwn^ sdn^
-»i =
4.
^
A
=
0,5m;
i?
=
A/
=
lOm/s
Cau 9:
4
fown^
son^ =
4.^ ->
A
=
30 cm; t;
=
A/
=

15m/s
Cau 10:
6
fcwn^
sdn^- / =
6.^ ->
A
=
0,6 m; i?
=
A/
=
60m/5
Cau 11:4
nut
3 bung song
A
T
/
=
3 *
A
=
0,8 m;-
=
0,055 =>
7 =
0,1s
1;
=

i =
8
m/s
Cau
12:
A
=
^
= ^ =
0,5m;
^ = 4
->
4
fcwn^,
5 nwt
Cau
13:
A
= - =
1cm;
j^
=
7
M la
nut
song
thu
7
f
•^/2

Cau 14:
A
=
^
=
0,25m; /
=
(5
+
i) ^
=
62,5cm;
5
bo song 6 niit song
Cau 15:
/ = = 4^ = 6^ /2 =
63//z
VAT
1Y
12
- TiM
TAT
lY
THUYf
T
VA
BAl
TAP TBAC
NGHIIM
- TAP

1
CHirOilG
2:
SANG
CI
Bai tap
5:
Cau 1
2.
3 4 5 6 7 8 9 10
Dap an C A C D C D C C B D
Cau 11 12 13 14 15
Dap an
c
D A A C
Cau 8: L
=
2B
=
20d5
=
10 Ig- ->
/ =
IO^IQ
'0
y,2
Cau 9:
L = 9B =
90dB
=

10
Igf
/
=
IO^/Q
=
0,001
W/m
'0
Cau 10:
L2
-
Z-i
=
20dB 10 Ig^
=
20 => /z
=
lOO/i
Cau 11:
/, = 1000/1 =» L2 - ^1 =
10 Ig^
=
30dB
'1
Cau 12:
-
LB
=
10 Ig^ =>

90
-
70
=
10 Ig^ =>
^ =
100
Cau 13:
- =
10 Ig^
=»
80
-
40
=
10 Ig^ =>
^ =
10000
Cau 14:
-
LB
=
10 Igy^
=
10 Ig
(^)
40
= 100
d^
+

dg
101
AM
= 2
'd
26dB
0
M
CHlTlMG
Z:
SANG
CK
V*T
lY
12
-
TIJM
TAT
lY THBYfT VA BAl
TAP
THAC
HGMlgM-TAPI
Cau 15:
L2 - = 10 \g'f = 10 Ig
(^f
=> 7 =
20
Ig
(Ji)
di

-62
62
=
2,24 di =
112m
d2
Cau hoi
trac nghiem
tong
hoD.
Cau
1
2
3
4
5
6
7 8 9 10
Dap
an
B D D
C C
B
A A
A A
Cau
11
12
13
14

15 16 17
18 19 20
Dap
an
B B
A A
D
C A
B D
A
Cau
7: 97 = 18s =» T = 2s,X = 2m,v = ^= Im/s
Cau
8: T = =
0,75s,
3A =
135cm
80
=>
A =
45cm;
v = ^ =
60cm/s
Cau
9: V = ^ =
5
j;
A
=
177

= 9m
Cau
10:
= 8cos27r
I
A
=
50cm
=
3s =>
Vthep
=
5294
m/s
Cau 11:
u =
8cos27r
- f) « w =
acos (a>t
- ^)
Cau 12:
u =
2cos(20:c
-
2000t)
=
2cos(2000t
- 20:c)
<-» u =
acos

a)t-
2nx\
,
TT ^ 1000
^
= = Hz -> t; = A/ =
lOOm/s
10
TT
Cau 13:
u = 6
cos(47rt
-
0,0027r;c) <->
u =
acos
(wt - ^)
->
A =
100cm
104
'^VjT lY
12
- TiM TAT LY THBYfT VA BAl TAP
TRAC
IGHieM - TAP 1
CHIflhlG2:Slill&Cir
Cau 14:
u =
2

cos
«^
u =
acos
2
(4nt -
O.Snx
- ^)] (cm)
/
27rx\
f
cot
-
A
/
A
=
2m;
/ = 4//z -> v = A/ =
8m/s
Cau 15:
- =
40cm
A =
80cm
=
0,8m;/
= - =
2,5Hz
2

A
Cau 16:
Acp
=/c27rd
= fcA = fc^/ = fc J
Voi
fc la s6
nguyen, ta chon
/ =
SOHz, khi
=
Cau 17:
Aa? = -— = —- = n + k2n => = — - -
^
A V w 2
98
< / < 102 => 2,93 < fc < 3,07 -> = 3 -> A = 4cm
Cau 18:
A = v7 =
t?—
=
20cm
27rx\
UM
= 2 cos
I
2nt - .
\ /
= 2
cos

cm
Cau
19
t
= 0,u = 0,v > 0 ->
uo
=
acos(^t
-f)
/2n
n 2nx\
UM
=
acos(-t —j
27rr
TT ^'^4
T
2
Cau 20;
5cm
=
acos
UM
=
acos(-^ j
2cm
=
acos
a
= 5cm

'2717
2713^
7
2
a
= 4cm
Cau
21
22 23
24
25
26
27
28
29
30
Dap
an
B
B
A
B
A C
D
C
A
A
Cau
31
32

33 34
35 36
37 38
39
40
Dap
an
B
D
B
A
D
D
D
C
A
A
105