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h "
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    
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π
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→ →
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 
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 

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14 =>?1@A1fAA2/"CDF 
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ϕ
λ
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∈
3#;i4
• &PQ 
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DAb
HJ+
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π
ϕ π
λ

[ ]
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⇒ − =E E 8
λ
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∈
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⇒
Tại những điểm này hai dao động thành phần cùng pha và biên độ dao động của sóng tổng hợp cực
đại.( d@>/C?kl/>/m)
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D
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π
ϕ π
λ

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λ
λ
6
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∈
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⇒
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tiểu.( d@>/C?kl/"U//m).
∗ d"CDEA"=/=1"//e1Xh8KP%"=1e1"R
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nEo'?5<!4TH'
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⇒
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:
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− = = =
Ba "5!?/(R$+%X(Y
DẠNG 2: G!>2(M(N"!#$,!6?R?/?&

C

KM("[b(c(J "!#$ "'d
<!
λ
X(%%&Y
@@
Be\*fg+
 
E E

ε
λ
−
= +
S"4+?&*RQ
ε
?&*R\**=
G>?>G==7&/U1GD=/0@@@V/ ./WQ<J7 AK

B
7
ε
=
?&"!#$'(W "'cực đạiBậc K= n
B

7 hM
ε
=
?&"!#$'(W "'cực tiểuBậc n + 1
DẠNG 3: G!"'?i(* (J  !6()O,!"!#$()$'*O4>2(M(N
"!#$,!6?R?/?&

C

KM("[>2(M(X(
λ
C%%&Y
@@
Ba3_(`(+
( )
( )
 
 

; E E
; E E 3 4

 
−
∆ = − = ∗
 
 
ω
π
ϕ

λ
7  "'()* 
c
ϕ π
∆ =
 %&
3 4∗ ⇒
"5!?/(R$
7 "'/(* 
( )
 c
ϕ π
∆ = +
 %&
3 4∗ ⇒
"5!?/(R$
7 "'%* 
( )
 

c
π
ϕ
∆ = +
 %&
3 4∗ ⇒
"5!?/(R$
• &PQ+
7cA
]

1A
\
1
Z
AA
^
3"CDEA"=1e1"4AA
\
/3"CDEA"=1e1/C4
\
>/\@
A`_
]
A
\
1
\


> 
λ
=
DẠNG 4: KM("[%[b%&g"!#$ "'(T("5!"5G-H,!%&G?& !64.
@@
B1j!?&"!#$ "'(T("5!"5G%&(M(CG?R?/U"5

C

S (4+
 


 
 
E E c
+5 c
E 3 4
E E +5
λ
λ
+ =

 
⇒ = + ∗

 
+ =
 

Bk

7 E +5≤ ≤
9/*%,!
3 4∗
a +
+5 +5
c
λ λ
 
− ≤ ≤
 

 

3 4∗ ∗
%,!
c w∈
• &PQ +
• dM("!#$ "'(T("5!"5G-b(2 !"!#$%&G%&G?& !"!#$ "'(T("5!.
(b?&!Ml(M(!M[9m $W(`(
3 4∗ ∗
• H[b(M("!#$ "'(T("5!nM("[<o(`(
3 4∗
DẠNG 5: KM("[%[b%&g"!#$ "'(T(!#"5G-H,!%&G?& !64.
@@
B1j!?&"!#$ "'(T(!#"5G%&(M(CG?R?/U"5

C

S (4+
 

 

 

 0
E E c
+5
E 3 c 4 3 4
E E +5
λ

λ

 
+ = +

 
 ÷
⇒ = + + ∗
 

 
 

+ =

Bk

7 E +5≤ ≤
9/*%,!
3 4∗
a +
 
 
+5 +5
c
λ λ
 
− − ≤ ≤ −
 
 


3 4∗ ∗
%,!
c w∈
• &PQ +
• dM("!#$ "'(T(!#"5G(b?&!Ml(M(!M[9m $W(`(
3 4∗ ∗
• H[b(M("!#$ "'(T(!#nM("[<o(`(
3 4∗
• &2/CEI1/U1A311J4"CVE#GEL
&1Jxb1"y0"CDEA"=1e1"G1e1/C/"+5
`T-OV-5i!'
G>?>G==7&/U1GD=/0@@@V/ ./WQ<J7 A#

 
= +
 
 
h
 j
λ
"2@9#%,!

 (∈
.QK@9/.@@a
FQV8KP1e1")!kh'#+Vl&
[ ]
 ; +
3xzHj/A"CD+M5>GA"CDEA"=1e1"4
SQV8KP1e1/C)!kh#+Vm&

[ ]
[ ]
7 h
  7 h
M ;
; z M

<


+ ≥


2n neáu X
neáu
• &PQxb1"y0"CDEA"=1e1"G1e1/C/8V+5
B$0EA"=1e1"+
 J;)<3xzHj4
 J;S<3xz
≠
j4
S$0"CDEA"=1e1/C/e/
[ ]
[ ]
7 h
  7 h
M ;
; z M

<



+ ≥


2n neáu X
neáu
J; AEA"=h1@A 3d//e11fAAN+M5>GEdEA"=1e1/C4
!-  . !-  .Q
ω π
= =

     
%&
!-  . !-  .Q
ω π π π
= + = +
h
     
A4 5"=1fA2/gh@ 
   
 

+ A;  3 E E 4 A; 1 3 E E 4
π π π
λ λ
 
 
= − = − +
 

 
 
 
3#;<J4
4 CDEA"=1e1" 
 

 
 
E E 3 8 4 3 8 4
λ
λ
 
− = + = +
 
 
3#;<K4
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