đề và đáp án kỳ thi HSG vật lý 2013 2014

SỞ GIÁO DỤC VÀ ĐÀO TẠO
QUẢNG TRỊ
KÌ THI CHỌN HỌC SINH GIỎI VĂN HÓA 12 THPT
Khóa ngày 05 tháng 03 năm 2014
 VẬT LÍ
180 
(Đề thi có 02 trang, gồm 05 câu)
Câu 1. (4 điểm)
 !"#$%&'!()*+
, /012 3 
% '
  4"56 7
= = π
 89+"
:7;<!1=>?&@1+A12-BC%'&
D1=9EFG"H%I'JK&L31=9EM4F
NG"H%NI'NJ(O&L7
a)A1EHD"&9#1=9EPB?DB7
b)QRSPHT012FC%'7A"HB?&B
?S7
c)UP*+129+B?+-V=%&
9!A%'7AW!XYU#-/%'7
Câu 2.(4 điểm)
?*+Z8A-[BG*+GYB*1237?
P*VG?-+\π%1P]&"W
^53GA9W_+247(6
`a
87
a)A3*+GY?7
b) bP&KLc]-$:+
?*+Z8-$*BdY-C+

*=D7e"XP93-
+*VG?9@f
c)g+GY?-9
*h"B_+-+*VGF+*=D,
-e3(7eiD1#90GA0_G7
Câu 3. (5 điểm)
8?G-e3 47j1Pk%1P' GG# TD
%'
 l 4 "(66 
= π
b&-D"HmC!1#
( 4
b &b
1P,#mk-$
P\6b&(46b1P4%G[!1#21PG[,#7'#
@GG#k
O
b
h"12GG#k1#
(
b
+
)
π
n
GG#k!1#
(
b
1P
4

b
G+
4
O
π
7
a)Ao&&Z&81Pl7
b)8G*8D:#!p8
(
"Hm
C1#
O
b
PB?7
`eiDT!p"HmC1#b
O
7
`b#90CGG#0kb
4
7
Câu 4. (4 điểm)
+VTG"HP J(66U^&H-$!@&
+k-$dHp&kV?-$X12H-$
(
J6&Le3
O78
(
-$X120H-$
4
J6&L78!

*+"!_qT@-2YHpdVT1
(^4
ĐỀ CHÍNH THỨC
A!
(
&
4
7gp+?41pA=9@"
VT9p< Wr7'F"0WC-78RHW1E7
a) b# 3*+VC!
&W#X127ZD1pA=
9@CPHR+7
b)8sX9p9#B<??#(U7e
4

9p!
(
fU#3![1pA1PPfb# 
3*+C
(
"
4
!7H1tD
-u7
Câu 5. (3 điểm)
vWk(T,PH-$
(
J4&6
-$,1Pq9@*=D,W&r&*PZJ(&67
vWk(@=9@!JL&63FWk4

H-$
4
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H1
6
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 /0
θ
J(46
6
3*=D+!?qS!
q+WTe357w&FWk(FDFqS
//07
a)A1EHCFWk
4
D"1?7
b)jFWk(BG-$D+V3W!HTW
9@9fZDJ(6^"
4
7'F"0WC-7
HẾT
• Thí sinh không được sử dụng tài liệu.
• Giám thị không giải thích gì thêm.
4^4
SỞ GIÁO DỤC VÀ ĐÀO TẠO
QUẢNG TRỊ
HƯỚNG DẪN CHẤM
ĐỀ THI CHỌN HSG VĂN HÓA 12 THPT

Môn: Vật lí - Khóa ngày: 05/03/2014
(Đáp án - thang điểm gồm 04 trang)
CÂU Ý
NỘI DUNG
Điểm
1
a)
QW"yP*+129+B?&
* % ' K&L 
∆ = − = = λ
(
*z %N 'N (O&L  4
∆ = − = = + λ
4
wD
O
=
cm
λ
1PJ4&L7
6&L
bEHD"
6&6O746 6&) ^
= = =
v f m s
λ
7
6&L
4&L
=

k
nP"H9!D1=9EPB7
6&L
b)
b3+*iDB0OY-BC%'?
S
`wH*+129+B?PL
6&L
`wH*+129+BP)7
6&L
c)
jU*+129+B?k%'@1A'&
jGB?
4 (
− =
d d
−NA NB
λ
= k

wH*+129+B?W%'
() ()
O O
− < < ⇔ − < <
l l
k k
λ λ

Uk%'JL&
() L O (− ⇒ = − =NA NB NB . cm

λ
= 5
6&4L
6&4L
jUeJT&
4 4 4 4
U% T U' T %e e'− + − = +
4 4 4 4
() T ( T () T 6&aaaL⇔ − + − = ⇒ =
6&L
6&L
2
a)
Tính chu kì dao động điện từ
`8-+*VG?*?
( )
( 6
 { " 
= ω + ϕ
`8-+*VG?M^5*?
( )
4 6 6
 { "  { " 
4
π
 
= ω + ϕ+ = − ω + ϕ
 ÷
 
6&L

g
4 4 4
( 4 6
  {
+ =
(
`!
4 4 4 4
4 4 6
F  {
ω + =
4
6&L
Y(1P4&
4 4 4 4 4
(
4 6 4 (
4

F {  
F
ω = − = ⇒ ω =
( )
)
4
 6&L7(6 "
−
π
⇒ = =
ω

7
6&L
b)
?
4 4
6
 6
{ O
O ( O (
| | Z Z{ 
5 4 5 4 4
 
= ⇒ = ⇒ = ±
 ÷
 

6&L
`xY&"XJ6P

∆
wy*_W 1,.FD&A-$
( ) ( )
 (
 " 6&6\O "
) (4
∆ = = = µ
7
6&L
c)
'0CGA9W_*?

( )
6
F F " = ω + ϕ
'0C-+*VG"}P
6
 { " 
4
π
 
= ω + ϕ+
 ÷
 

O^4
π/6
π/3
π/3
L
U

4
U

rR
U
+

(
U


R
U

O
U

)
)
4 4 *
5 7(6
 6&L7(6 "
−
π π
ω = = = π
n
O
a
6
6
)
{
\ 47(6
F 4 47(6 8
5 7(6
−
−
π
= = =
ω π
7

6&4L
6&4L
Y p[Hình 1&D?
 6=
3
6 6
 { " {
4
π
 
= ϕ+ =
 ÷
 

6
4 4
π π
⇒ ϕ + = ⇒ ϕ = −
7
bED
)
F 4 4 " 5 7(6  8
4
π
 
= π −
 ÷
 
7
6&L

6&L
3
a)
`QW 1,.
6&4L
,W 1,.
o (
(
l l " \67 56b
) 4
π
= = =

746
4
56
Ω===⇒
I
U
R
R
6&L
8 (
O
l l " \67 56 Ob
O 4
π
= = =
Ω===⇒
O46

4
O56
I
U
Z
C
C
7a4 FC
µ
≈⇒
6&L
Z 4
O
l l " (467 )6 Ob
O 4
π
= = =
Ω===⇒
OO6
4
O)6
I
U
Z
L
L
7()L&6 HL
≈⇒
6&L
o  4

(
l l l " (467 )6b
) 4
π
+ = = =
46 VU
r
=⇒
7(6
Ω=⇒
r
6&L
44

CL
ZZrRIU
−++=
7O56O(6O64
44
V
=+=
6&4L
b)
* Số chỉ cực đại của vôn kế V
3

44

CL
C

CC
ZZrR
UZ
IZU
−++
==
(4

4
44
+−
++
=
C
L
C
L
Z
Z
Z
ZrR
U
(
'0]P+09EC
C
Z^(
&*
C
U
?B?

13lJ"?
6&L
5^4

(
Z
4 4
8 8 Z
~( (
~ ~ o  ~
= =
+ +

(
4 4
Z
8
Z
o  ~
~ 56 O
~
+ +
⇒ = = Ω
7
D  1P  (    A  -$  !  p  B  ?  C 
C
U

9@
4 4

Z
8T
l o  ~
l \6 O b
o 
+ +
= =
+
7
bED"HmC1#b
O
P
\6 Ob
.
6&4L
6&4L
`Chứng tỏ được:xGG#dk_G!plớn nhất&
GG#dkb
4
"2π^4GG#k??7
YW 1,.&
4 4 4
8T %' 4
l l l
= +

6&L
( ) ( )
4 4
4 4

4 8T %'
l l l \6 O 56 O (46b
⇒ = − = − =
7
`'0GG#kb
4

( )
4
 (46 4 " (66  b
4
π
 
= π +
 ÷
 
6&L
6&L
4
4
a)
- Phương trình d+VCG1E*R_CVT
N 3*+*?
( )
T %" 
= ω + ϕ


( 4
 (66

*
(6
"
  6&L 6&L
ω = = =
+ +
7
6&L
8RH
6 6
 6nT 4n1 6
= = − =

%" 4 *
% " 6 % 4
ϕ = − ϕ = π
 
⇒ ⇒
 
− ω ϕ = =
 
( ) ( )
T 4 " (6 
= + π
6&L
6&L
b)
8RGFD#X12
(
7eGFD#PDPev8F!A&*

(
D+H7x
4
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4
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4
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4
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4
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6&L
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= = ⇒ ω =
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€ T € 6&64 4
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4
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bED
4
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4
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T % z" z z
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T  %z" (6 4 z 4
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bEDFWk(D+V12W!
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T Z o 6&K ≥ − =
7
6&L
Ghi chú: Thí sinh có thể giải cách khác nếu đáp số đúng thì cho điểm tối đa, sai phần nào
thì trừ điểm ngang phần đó.
Hết
)^4