mot phan tu hudc song.. mot birdrc song.. Tren mot spi day dan hoi dang c6 song dufng.. Giai Trong mach dao dong LC l i ttfdng dang c6 dao dong dien tCf t\i do, CLfdng do dong dien tron
Trang 1Gi^i
Hai van sang t r u n g nhau nen: 5X^ = kXj => k = = 6
^ 2
Vdy chon dap an B
Cdu 27: Chiet suat cua mot thuy t i n h doi vdri mot a n h sang dorn s S c la
1,6852 Toe do cua anh sang nay trong thuy t i n h do l a :
A l,78.10Ws B l,59.10Ws C l,67.10Ws D l,87.10Ws
Taco: v = - = ^'^^ = l,78.10Ws
n 1,6852
Vdy chon dap an A
Cdu 28: Quan sat song dCtog t r e n scfi day A B , dau A dao dong dieu hoa
tan so dao dong cua dau A l a 22 Hz t h i t r e n day c6 6 nut Neu dau B
tan so dao dong cua dau A phai bkng:
A 18 Hz B 25 Hz C 23 Hz D 20 Hz
T a c o : K h i B t u do: / = (2k + l ) - = (2.5 + 1 ) - ^ = 1 1 - ^ (1)
4 , 4f, 4f,
K h i B CO dinh: / = k - = 5 — (2)
2 2 f 2
TCf (1) v a 2) suy ra: fa = 20Hz
Vdy chon dap an D
Cdu 29: T r e n mot stfi day dan hoi dang c6 song dCfng Khoang each tii
mot nut den mot bung k e n o bang
C mot phan tu hudc song D mot birdrc song
Tren mot spi day dan hoi dang c6 song dufng Khoang each tCr mcTt
nut den mot bung k e n o bkng mot phan tiT h\i6c song
Vdy chon dap an C
Giii Chi ti^t 66 thi TS DH CO M6n V$t If 141
Trang 2Cdu 30:
GiOfa ano
t v
a cato
t cu
a mo
t on
g pha
t ti
a X c6 hie
u die
n th
e
khong dd
i l
a 2
5 kV B
o qu
a don
g nan
g cu
a electro
n kh
i buf
t r
a tO
f catot
Birdfc son
g nghn
nhat cu
a ti
a X
ma on
g c
6 th
e pha
t r
a bkng :
A 31,5
7 pm B 39,7
3 pm C 49,6
9 pm D 35,1
5 pm
he h
e — ^,„,„ = U^, ^ = e : — Ta co
— = 49,69 pm
Vay chqn dap an
C
Cdu 31:
M
ot kim
loai c
6 gidf
i h an quang die
n l
a XQ
Chie
u buf
c x
a c
6
hxidc son
g ban
g ^ vao
k im loai nay Ch
o r kn
g nan
g Itfofn
g m
a
electron quan
g die
n ha
p th
u tC
r photo
n cu
a buf
c x
a tren , mo
t pha
n dun
g
de gia
i phon
g no , pha
n co
n l
ai bie
n hoa
n toa
n than
h don
g nan
g cu
a
no Gi
a t
ri don
g nan
g na
y la :
A.
^.
B J
^
C.
^.
D ^
Giai
Ta c6
3 = ^ +
,=
>W ,=
^-^ = 2
^
Vdy chon dap an
D
Cdu 32:
K
hi no
i v
e an
h san
g dcfn sac, pha
t bie
u na
o sa
u da
y dung
?
A An
h san
g dcf
n sa
c khon
g b
i t an sfic kh
i truye
n qu
a lan
g kinh
B An
h san
g tran
g l
a an
h san
g dcf
n skc
v
i n
o c
6 ma
u trang
C To
e d
o truye
n cu
a mo
t an
h san
g dcf
n sa
c tron
g niXdc
va tron
g
khong kh
i l
a nhi
X nhau
D Tron
g thu
y t in
h, ea
c an
h san
g dcf
n sa
c kha
c nha
u truye
n v6
i to
e
do nhi
f nhau
Giai
Chi CO dap an
A diing, cdc dap
an con lai deu
sai
Cdu 33:
Trong mac
h da
o don
g L
C l
i tLfdn
g dan
g c
6 da
o don
g die
n til
tiX
do, cifofn
g d
o don
g die
n tron
g mae
h v
a hie
u die
n th
e giUa
hai ba
n t
u
dien l3e
h ph
a nha
u m
ot go
c bSng :
A - B 71
C
- D
0
142 GiaichitifitdlthiTSDH, CE)M6nV$tl
(
Trang 3Giai
Trong mach dao dong LC l i ttfdng dang c6 dao dong dien tCf t\i do,
CLfdng do dong dien trong mach va hieu dien the giffa h a i ban t u dien
lech pha nhau mot goc bang
Vay chgn dap an C
Cdu 34: K h i noi ve t i a tuT ngoai, phat bieu nao sau day sai?
A Tia tijf ngoai la song dien tii c6 t a n so nho hofn t a n so cua anh
sang t i m
B Trong y hoc, t i a tijf ngoai dtrofc dung de chOfa benh coi xiiofng
C Trong cong nghiep, t i a tuf ngoai difcrc dung de phat h i e n cac vet
nurt t r e n be mSt cac san pham k i m loai
D Tia tuf ngoai c6 tac dung manh len p h i m anh
Giai
Phat bieu sai l a : T i a tuf ngoai la song dien tuf c6 t a n so nho horn
tan so cua anh sang t i m
Vay chgn dap an A
Cdu 35: K h i noi ve hat sof cap, phat bieu nao sau day d u n g ?
A Ncftrino la h a t sof cap c6 k h o i luang nghi bang k h o i lUgfng nghi
cua electron
B Tap htfp cac mezon va cac barion c6 t e n chung la cac hadron
C Proton la h a t scf cap c6 phan hat la nortron
D Phan tuf, nguyen tuf la nhufng hat scf cap
Giai
Chi CO dap an B dung, cac dap an con lg,i diu sai
Cdu 36: Dat dien ap xoay chieu u = Uocos27cft (Uo khong doi, f thay doi
dirgrc) vao hai dau doan mach chi c6 tu dien Phat bieu nao sau day dung?
A Dien ap giufa hai dau doan mach s6m pha so vdi ciTdng do
dong dien trong doan mach
B Ctfcfng do dong dien hieu dung trong doan mach cang lorn k h i
tan so f cang Idn
C Dung k h a n g cua tu dien cang Idn k h i t a n so f cang Idm
D Ctfcfng do dong dien hieu dung trong doan mach khong doi k h i
tan so f thay doi
GiSi chi tiet thi TS DH, CD M6n vat l( 143