Thời gian làm bài : 90 phút
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Cho: hằng số Plăng h = 6,625.10
-34
J.s, tốc độ ánh sáng trong chân không c = 3.10
8
m/s;
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-19
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23
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-1
.
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max x
x x x x x x
x x x t cm d A cm
π
∆
∆ = − ∆ = −
∆ = − = ⇒ = =
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2
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4 3
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t t s T s rad s
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2
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+ §èi víi bµi nµy M, N thuéc cùc
∆ = − = ∆ − ∆ ∆ = −
∆ = ∈
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M
M
M
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M k k Z
M k k Z
λ
ϕ ϕ ϕ ϕ ϕ
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ϕ π
ϕ
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1 2
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4
tiÓu nªn: 2 1 . 4 1,5
2 2
+ V× gÇn nhÊt nªn 0 2 1,5 5
+ V× M gÇn O nhÊt nªn 2 4 1,5 3,65 3 7,5
∆ = − = + + = +
= ⇒ ∆ = − = = ⇔ =
⇒ ∆ = − = = + < ⇔ < ⇒ = ⇒ =
d d d k k cm
M O k d d d OM cm OM cm
d d d ON k AB k k ON cm
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π
π
A
B
B
M
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2
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1 2
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1 2 1 2
i 1 2 1 2
2 2
2 2 2 2 2 2 2 2 2
1 2 1 2 1 1
;
2
XÐt bµi to¸n tæng qu¸t nh sau:
.
Ta cã: ; cos cos 1 1
2 2
.
i
MB MB
R L C R MB
R R
i R R
R MB R MB R MB MB
U k U
U U U U U U
U U
U U U
U U
U U U U U U U k U U
π
ϕ ϕ
π π
ϕ ϕ ϕ ϕ ϕ ϕ
=
=
= + − = +
= ⇒ + = ⇒ + = ⇔ + = ⇔ = +
⇔ = + − ⇔ = ⇔ = ⇔
( )
( )
( ) ( ) ( )
( )
( )
( )
( )
( )
2
1
2
1
2
2
1
2 2 2 2
1 1 1 1
2
2
2 1
1
2
.
MÆc kh¸c ta cã: U
1
150.2 2
LiÒn, ngay vµ lËp tøc ¸p dông c«ng thøc trªn ta cã: 2 2 2 2 100 2
2 2 1
R
R
R MB R R
R
U
k
U
U k
U U U U
k
k
U U k U V
=
= + = + ⇒ =
+
= ⇒ = ⇒ = =
+
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( ) ( )
2
2
2
2
2 2
2
2 4 2
2 2 2
2 2
0
1 . 1 .
+ Khảo sát công thức tính công suất: .
1 1 1
2 2
1
2
1 1
+ Đặt ta có: 2 , khảo sát hàm số
Khi rôto quay với tốc độ
x x
E NBS R NBS R
P I R
L
Z
R L
R L
C C
C
L
x f x R x L f
C C
n
= = = =
+ +
+
ữ
ữ
= = + +
ữ
+
( )
( )
( )
( )
( )
( ) ( ) ( )
2 2
0
1 2 1 2 1 2 1 2
0 1 2
2 2 2 2
0 1 2 0
1
thì 2 , 1
2 2
+ Khi rôto quay với tốc độ hoặc thì 0 có 2 nghiệm phân biệt và . Ta có: , 2
1 1 1 1 1 1 1 1
+ Từ 1 và 2 hay
2 2 2
max
x
x
b
P f min x LC R C
a
b
n n P P f x x x x
a
x x x
n n
= =
= = + =
= + = + =
ữ
2 2
2
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