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ThS Nguyn Thanh Dng, ThS Phng Nht Anh TT BDVH v LTHThnh Tr(Nguyn TT BDVH v LTHH Kinh tTP. HCM)

C: 279 Nguyn Tri Phng Qun 10 (T:38575676); 10/5 Trn Nht Dut Qun 1 (T:22405332) TP.HCM

BI GII CHI TIT THI TUYN SINH I HC KHI A NM 2010Mn thi : VT L M 485 (Thi gian lm bi: 90 pht)

1

Cho bit hng s Plng h = 6,625.10-34 -19J.s; ln in tch nguyn t e = 1,6.10 C; tc nh sng trongchn khng c = 3.108 m/s.I. PHN CHUNG CHO TT C TH SINH (40 cu, tcu 1 n cu 40)Cu 1: t in p xoay chiu c gi tr hiu dng khng i, tn s 50Hz vo hai u on mch mc ni

tip gm in trthun R, cun cm thun c t cm L v tin c in dung C thay i c. iu

chnh in dung C n gi tr410

4F

410

2F

hoc th cng sut tiu th trn on mch u c gi tr

bng nhau. Gi tr ca L bng

A.1

.2

H

B.2

.H

C.1

.3

H

D.3

.H

1 21 2 1 2 1 2 L C L CP P I I Z Z Z Z Z Z= = = = Cu 1: D. . Theo bi:

1 2C CZ 400 ; Z 200= =

1 2C CL

Z Z 3Z 300 L H

2

+= = =

.

Cu 2: Mt mch dao ng in t l tng ang c dao ng in t t do. Ti thi im t = 0, in tchtrn mt bn tin cc i. Sau khong thi gian ngn nht t th in tch trn bn t ny bng mt nagi tr cc i. Chu k dao ng ring ca mch dao ng ny l

A. 6t. B. 12t. C. 3t. D. 4t.

Cu 2:A. Khong thi gian ngn nht in tch ca t gim t cc i xung cn mt na0Q0Q

2l:

Tt T 6

6 = = t .

Cu 3: Ti ni c gia tc trng trng g, mt con lc n dao ng iu ha vi bin gc 0 nh. Lymc th nng v tr cn bng. Khi con lc chuyn ng nhanh dn theo chiu dng n v tr c ng

nng bng th nng th li gc ca con lc bngA. 0 .

3

B. 0 .

2

C. 0 .

2

D. 0 .

3

2 2 00

1 1mg 2 mg

2 2 2

= = Cu 3:C. Khi W = W th W = 2W t t . Con lc ang chuyn ng

nhanh dn theo chiu dng Con lc ang chuyn ng v pha VTCB theo chiu dng 02

= .

Cu 4:t in p u = 2 cosU t vo hai u on mch AB gm hai on mch AN v NB mc nitip. on AN gm bin trR mc ni tip vi cun cm thun c t cm L, on NB ch c tin

vi in dung C. t 1 12 LC = . in p hiu dng gia hai u on mch AN khng ph thuc R

th tn s gc bng

A. 1 .2 2

B. 1 2. C.

1 .2

D. 2 .1

2 2L

AN AN 2L C

U. R ZU IZ

R (Z Z )

+= =

+ Cu 4: B. in p hiu dng gia hai u on mch AN:

2

R (Z Z ) Z 2Z 2LC 1+ = + = =

.

khng ph thuc vo R th: R Z (1). Theo bi:

ANU

2 2 2 2 2L L C C L

2

121 2 2= =

2

1

1

42= LCLC 1 1= (2). T (1) v (2) suy ra: . Cu 5: Cho ba ht nhn X, Y v Z c s nucln tng ng l AX, AY, AZ vi A = 2AX Y = 0,5AZ. Bit nnglng lin kt ca tng ht nhn tng ng l EX, EY, EZ vi E < EZ X < EY. Sp xp cc ht nhnny theo th t tnh bn vng gim dn l:

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OM2 1

T50

= =

Cu 9: C. Chu k: s . Biu din in p u bng vectquay quay theo chiu dng lng

gic. Ti thi im t, 01U

u 100 2 V2

= =

3

v ang gim tng ng vi im M trng M1. Sau thi im

1 Tt s 2.

300 6 12 = = =

T. t

3

= = , khi M trng Mtng ng vectOM qut mt gc 2in p

lc : 02 Uu 100 2 V2= = .

Cu 10: Mt kim loi c cng thot lectron l 7,2.10-19J. Chiu ln lt vo kim loi ny cc bc x cbc sng 1 = 0,18 m; 2 = 0,21 m, 3 = 0,32 m v 4 = 0,35 m. Nhng bc x c th gy ra hintng quang in kim loi ny c bc sng l

A. 1, 2 v 3. B. 1 v 2. C. 3 v 4. D. 2, 3 v 4.

Cu 10:B. Gii hn quang in ca kim loi:34 8

70 19

hc 6, 625.10 3.102,76.10 m 0, 276 m

A 7,2.10

= = = . V

1 v 2 nh hn 0 nn ch c hai bc x ny gy ra hin tng quang in vi kim loi cho.

Cu 11: Tia t ngoi c dngA. tm khuyt tt bn trong sn phm bng kim loi.B. tm vt nt trn b mt sn phm bng kim loi.C. trong y t chp in, chiu in.D. chp nh b mt Tri t t v tinh.

Cu 11: B. Tia t ngoi c dng tm vt nt trn b mt sn phm bng kim loi.Cu 12: Ni hai cc ca mt my pht in xoay chiu mt pha vo hai u on mch AB gm in trthun R mc ni tip vi cun cm thun. B qua in trcc cun dy ca my pht. Khi n vng/pht thcng dng in hiu dng trong on mch l 1 A. Khi rto ca my quay u vi tc 3nvng/pht th cng dng in hiu dng trong on mch l 3 A. Nu rto ca my quay u vi tc 2n vng/pht th cm khng ca on mch AB l

A. 2 3R . B.2

3

R. C. 3R . D.

3

R.

Cu 12: B. Tn s bin thin ca sut in ng v sut in ng cc i do my pht in mt chiu to

ra: 0np

f ;E NBS 2 fNB60

= = = Sin p hiu dng hai u mch: 0E

U E 2 fNBS2

= = = .

+ Khi rto ca my quay u vi tc 1n n= v 2n 3n= th f 22 1 L L1 2 13f Z 3Z ;U 3U= = = . Theo

: 2 11 2 2 1 2 1Z ( )2 1

U 3UI 1A;I 3 A I 3 I Z 3

Z Z= = = = =

1 1 1

22 2 2L L L

RR 3Z 3(R Z ) Z

3 + = + = .

+ Khi rto ca my quay u vi tc 3n 2n= th 33 1 L L1 2Rf 2 .f Z 2Z 3= = =

u (V)

1M (t)2T

M t6

+

0U

(+)

0U

20U

2

O

=3

T

12

T

12

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Cu 13:t vo hai u cun scp ca mt my bin p l tng (b qua hao ph) mt in p xoaychiu c gi tr hiu dng khng i th in p hiu dng gia hai u cun th cp h l 100V. cun th cp, nu gim bt n vng dy th in p hiu dng gia hai u hca n l U, nu tng thmn vng dy th in p l 2U. Nu tng thm 3n vng dy cun th cp th in p hiu dng gia haiu hca cun ny bng

A. 100V. B. 200V. C. 220V. D. 110V.

2

1 1

U N

U N=Cu 13:B. Cng thc my bin p: = 100 V (1).2 vi U

2

2

'

2

1 1

U N n

U N

=

2

'U U=+ Nu gim bt s vng cun thc c p n vng th: vi

4

(2).

2

''

2

1 1

U N n

U N

+=+ Nu tng s vng cun thc c p n vng th: vi (3).

2

''U 2U=

22

2

N n2 N

N n

+= =

3n .Chia (3) cho (2) v theo v:

2

'''

2

1 1 1

U N 3n 2N6n

U N N N

+= = =+ Nu tng s vng cun thc cp 3n vng th: 2

1

(4). So snh (4) v (1) ta

c: .2

Cu 14: Mt cht im dao ng iu ha vi chu k T. Trong khong thi gian ngn nht khi i t v tr

bin c li x = A n v tr x =

'''2U 2U 200V= =

2

A, cht im c tc trung bnh l

A.6

B..A

T

9. C.

2

A

T

3. D.

2

A

T

4.

A

T

2

ACu 14:B. Khong thi gian ngn nht cht im i t x = A n x = l:

T T Tt

4 12 3= + = . Qung

ng cht im i c: A 3As A2 2

= + = tb s 9Av .t 2T= = Tc trung bnh:

Cu 15: Khi lectron quo dng th n th nng lng ca nguyn t hir c tnh theo cng thc

2

13,6nE

n= (eV) (n = 1, 2, 3,). Khi lectron trong nguyn t hir chuyn t quo dng n = 3 sang

quo dng n = 2 th nguyn t hir pht ra phtn ng vi bc x c bc sng bngA. 0,4861 m. B. 0,4102 m. C. 0,4350 m. D. 0,6576m.

3 22 2

13,6 13,6E eV 1,511eV;E eV 3,400eV

3 2= = = Cu 15:D. Ta c: ;

34 87

3 2 32 1932 3 2

hc hc 6,625.10 3.10

E E 6,576.10 m 0,6576 mE E ( 1,511 3,400)1,6.10

= = = = + .Cu 16: Theo mu nguyn t Bo, bn knh qu o K ca lectron trong nguyn t hir l r0. Khilectron chuyn t quo N v quo L th bn knh quo gim bt

A. 12r0. B. 4 r0. C. 9 r0. D. 16 r0.Cu 16: A. Bn knh quo dng N v L ln lt l: Khi lectron

chuyn t quo N v quo L th bn knh quo gim bt 12 .

2 2N 0 0 L 0r 4 r 16r ; r 2 r 4r = = = = 0

r0Cu 17: Trong th nghim Y-ng v giao thoa nh sng, hai khe c chiu bng nh sng trng c bcsng t 380 nm n 760 nm. Khong cch gia hai khe l 0,8 mm, khong cch t mt phng cha hai khen mn quan st l 2 m. Trn mn, ti v tr cch vn trung tm 3 mm c vn sng ca cc bc x vi

bc sngA. 0,48 m v 0,56 m. B. 0,40 m v 0,60 m.C. 0,40 m v 0,64 m. D. 0,45 m v 0,60 m.

MM

x .ak D 1,2x m

a kD k

= = = Cu 17: B. Ti M cch vn trung tm 3 mm l vn sng: .

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C: 279 Nguyn Tri Phng Qun 10 (T:38575676); 10/5 Trn Nht Dut Qun 1 (T:22405332) TP.HCM 5

V1,2

0,38 m 0,76 m 0,38 0,76 1,58 k 3,16k

k = 2 v k = 3.

Khi k = 2 th = 0,6 m ; Khi k = 3 th = 0,4 m.Cu 18: Mt con lc l xo dao ng iu ha vi chu k T v bin 5 cm. Bit trong mt chu k, khong

thi gian vt nh ca con lc c ln gia tc khng vt qu 100 cm/s3

T2 l . Ly 2=10. Tn s dao

ng ca vt lA. 4 Hz. B. 3 Hz. C. 2 Hz. D. 1 Hz.

Cu 18:D. Gia tc: 2 2a x a= = x ln gia tc khng vt qu 100 cm/s2 ( a 100

cm/s2) th N Mx x x x x N Vt chuyn ng trn on thng MN nhn O lm trung im im.

26 1

=T T2Trong na chu k th khong thi gian 100 cm/s la

2cng l thi gian ngn nht cht

im i t M n N hoc ngc li M NA A

x ; x2 2

= = .

a 1002

x 2,5

Ax

2

=Vy khi = 2,5 cm th a 100= cm/s2 rad/s = = = f 1 .Hz

2

= =

N

Ax

2MA

x2

= =

Cu 19:t in p xoay chiu c gi tr hiu dng 200 V v tn s khng i vo hai u A v B caon mch mc ni tip theo th t gm bin trR, cun cm thun c t cm L v tin c indung C thay i. Gi N l im ni gia cun cm thun v tin. Cc gi tr R, L, C hu hn v khc

khng. Vi C = C1 th in p hiu dng gia hai u bin trR c gi tr khng i v khc khng khi

thay i gi tr R ca bin tr. Vi C = 12

Cth in p hiu dng gia A v N bng

A. 200 V. B. 100 V. C. 100 V. D.2 200 2 V.

Cu 19:A.

+ Khi C = C1:1

R R 2 2L C

U.RU IZ

R (Z Z )= =

+ RU. khng ph thuc vo R th: .1L CZ Z=

+ Khi C = C2 = 1

2

C: ; vi

2 1C C

Z 2Z= 'AN AN

U ' I 'Z=1

' 2 2 2 2AN L CZ R Z R Z= + = +

'

AB AB

U I 'Z=; vi

2 1 1 1

' 2 2 2 2 2 2AB L C C C CZ R (Z Z ) R (Z 2Z ) R Z= + = + = +

' ' 'AN AB AN ABZ Z U U 200V= = =; V .

Cu 20: Mt mch dao ng l tng gm cun cm thun c t cm 4 H v mt tin c in dungbin i t 10 pF n 640 pF. Ly 2 = 10. Chu k dao ng ring ca mch ny c gi tr

A. t 2.10-8s n 3.10-7s. B. t 4.10-8s n 3,2.10-7s.C. t 2.10-8s n 3,6.10-7s. D. t 4.10-8s n 2,4.10-7s.

Cu 20:B. Chu k dao ng ring ca mch dao ng: T 2 .LC=

+ Khi C = C1 = 10 pF th:6 12 82 LC 2 4.10 .10.10 4.10 s = = T .

+ Khi C = C2 = 640 pF th: 6 12 72 LC 2 4.10 640.10 3,2.10 s = = T .Cu 21: Mt si dy AB di 100 cm cng ngang, u B cnh, u A gn vi mt nhnh ca m thoadao ng iu ha vi tn s 40 Hz. Trn dy AB c mt sng dng n nh, A c coi l nt sng. Tc truyn sng trn dy l 20 m/s. K c A v B, trn dy c

O A-A

T

12

T

12T

6 T

6

xM N

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Cu 25: Phng x v phn hch ht nhnA. u c s hp th ntron chm. B. u l phn ng ht nhn thu nng lng.C. u l phn ng ht nhn ta nng lng. D. u khng phi l phn ng ht nhn.

Cu 25:C. Phng x v phn hch ht nhn u l phn ng ht nhn ta nng lng.Cu 26: t in p xoay chiu c gi tr hiu dng v tn s khng i vo hai u on mch gm bintrR mc ni tip vi tin c in dung C. Gi in p hiu dng gia hai u tin, gia hai u

bin trv h s cng sut ca on mch khi bin trc gi tr R

7

1 ln lt l UC1, UR1 v cos1; khi bin

trc gi tr R th cc gi tr tng ng ni trn l U2 C2, UR2 v cos2. Bit UC1 = 2UC2, UR2 = 2UR1. Gi trca cos1 v cos l:2

A. 1 21

cos ,cos3 5

=2

= . B. 1 21 1

cos ,cos5 3

= = .

C. 1 21

cos ,cos5 5

=2

= . D. 1 21 1

cos ,cos2 2 2

= = .

Cu 26: C. V ;1 2C C 1 C 2 C 1 2

U 2U I Z 2I Z I 2I= = = R R 2 2 1 1 2 2 2 1U 2U I R 2I R I R 2.2I R 2 1= = =

( ;2 1R 4R= )2 2 2 2 2 2 2 21 2 2 1 2 C 1 C 1 C 1 C C 12I Z 2Z R Z 4 R Z 16R Z 4R 4Z Z 2R = = + = + + = + =I 2 2 1 2 1

1 1 C 1 1 2 11 2 1

R R 4R 1 2

Z R Z 5R cos ;cos 2cosZ Z 2Z5 5= + = = = = = = = .Cu 27: Trong th nghim Y-ng v giao thoa nh sng, hai khe c chiu bng nh sng n sc c

bc sng 0,6 m. Khong cch gia hai khe l 1 mm, khong cch t mt phng cha hai khe n mnquan st l 2,5m, b rng min giao thoa l 1,25 cm. Tng s vn sng v vn ti c trong min giao thoal

A. 19 vn. B. 17 vn. C. 15 vn. D. 21 vn.D

Cu 27:B. Khong vn: i 1,5mma

= = ; S khong vn trong na vng giao thoa:

L 12,54,16

2i 2.1,5=

= 2.4 + 1 =9; S vn ti: N S vn sng: Ns T = 2.4 = 8 (v phn thp phn l 0,16 < 0,5) Tng s vnsng v vn ti c trong min giao thoa l: N = NS + NT = 9 + 8 = 17 vn.Cu 28: Mt con lc l xo gm vt nh khi lng 0,02 kg v l xo c cng 1 N/m. Vt nhc ttrn gi cnh nm ngang dc theo trc l xo. H s ma st trt gia gi v vt nh l 0,1. Banu gi vt v tr l xo b nn 10 cm ri bung nh con lc dao ng tt dn. Ly g = 10 m/s2. Tc ln nht vt nht c trong qu trnh dao ng l

A. 10 cm/s. B.30 20 6 cm/s. C. cm/s. D. 40 3 cm/s.40 2Cu 28:C.

OOM N (+)

A '

0 10cm =

Gi x l v tr m vt t tc ln nht trong qu trnh dao ng (cng l tc ln nht m vt tc trong 1/4 chu k u tin). Ta s chng minh v tr khng phi l O m l O c ta .O'x

Theo nh lut bo ton nng lng, cnng ca h ti M (th nng n hi ca l xo) bng tng cnng ca h ti O (gm ng nng ca vt v th nng n hi ca l xo) v ln cng ca lc ma st( ms ms 0A F s mg.(= = + x) ):

2 2 2 2 2 20 0 0

1 1 1 k k k mv kx mg.( x) v x 2 g.( x)

2 2 2 m m = + + + = + 0

2 2 2

0 0

k k

v x 2 g.(t y = x)m m= +

max maxv y(*) 2k mg

x 0,02mk

2cm

= = = Ta c: y ' ; y = 0 x 2 gm

= .

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Kho st s bin bin ca y, ta thy khi x = -2 cm th ymax, ngha l vt t tc ln nht ti O c li x = -2cm. Thay x = -2cm vo (*), ta c:

( )2 2max 0 0k

v x 2 g.( x)

8

0,3m

= + = 2 m/s = 0, m/s =4 2 cm/s.40 2

CCH GII SAI:

Tc ln nht vt t c trong qu trnh dao ng l tc ca vt i qua v tr cn bng ln utin. Khi , c nng ca con lc bng tng ng nng ca vt v ln cng ca lc ma st2 2

max

1 1kA mv mg.A

2 2= + . Ta c:ms msA F s mg.A mg.A= = =

2 2

max

kA 1.0,1v 2 g.A 2.0,1.10.0,1 0,3

m 0,02= = = m/s =

Cu 29: Xt hai mch dao ng in t l tng. Chu k dao ng ring ca mch th nht l T1, ca mchth hai l T2 = 2T1. Ban u in tch trn mi bn tin c ln cc i Q0. Sau mi tin phngin qua cun cm ca mch. Khi in tch trn mi bn t ca hai mch u c ln bng q (0 < q < Q0)th t s ln cng dng in trong mch th nht v ln cng dng in trong mch th hail

A.1

. B.4

1. C. 4. D. 2.

2

Cu 29:D. Chu k:2

T . V T

= 2

2 = 2T1 1 2 = ; Cng dng in cc i ca hai mch dao

ng ln lt l: I Q . Cng thc c lp vi t gia q v i ng vi hai mch

dao ng ln lt l:01 1 0 02 2 0 01 02; I Q I 2I= = =

2 2 2 2

1 1 2 2

0 01 0 02

q i q i1; 1

Q I Q I

+ = +

= . V 1 2 1 011 2

01 02 2 02

i i i Iq q q 0

I I i I2= = > = = = .

Cu 30: Lc ko v tc dng ln mt cht im dao ng iu ha c lnA. t l vi ln ca li v lun hng v v tr cn bng.B. t l vi bnh phng bin .C. khng i nhng hng thay i.D. v hng khng i.

Cu 30: A.Lc ko v tc dng ln mt cht im dao ng iu ha c ln t l vi ln ca li

v lun hng v v tr cn bng.Cu 31: Mt cht c kh nng pht ra nh sng pht quang vi tn s 6.1014 Hz. Khi dng nh sng cbc sng no di y kch thch th cht ny khng th pht quang?

A. 0,40 m. B. 0,45 m. C. 0,38 m. D. 0,55 m.Cu 31:D. nh sng pht quang c bc sng ln hn bc sng ca nh sng kch thch. Ta chn gi tr

bc sng ln nht trong bn gi tr bc sng trn l = 0,55 m.Cu 32: Ht nhn 210 ang ng yn th phng x, ngay sau phng x, ng nng ca ht 84Po

A. ln hn ng nng ca ht nhn con.B. ch c th nh hn hoc bng ng nng ca ht nhn con.C. bng ng nng ca ht nhn con.D. nh hn ng nng ca ht nhn con.

Cu 32:A. Phng trnh phng x: . nh lut bo ton ng lng:210 4 20684 2 82Po He Pb +

b b

2 2 PbP P Pb Pb Pb Pb

Pb

K m 206p p 0 p p p p 2m K 2m K 1 K K

K m 4

+ = = = = = > >

.

10 cm/s.30

Cch gii ny sai v vtr cn bng mi ca vt khng phi l O m l O. Bin dao ng cavt khng bng 10 cm m nh hn. Cu ny hu ht gi gii ca Bo Thanh nin, Bo Tui trvmt sBo mng khc u sai.

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2 21 mv p 2mK 2

=Ghi ch: ln ng lng: p = mv; ng nng: K = W = .

Cu 33: Quang ph vch pht xA. ca cc nguyn t khc nhau, cng mt nhit th nh nhau v sng ti ca cc vch.B. do cc cht rn, cht lng hoc cht kh c p sut ln pht ra khi b nung nng.C. l mt di c mu tn tm ni lin nhau mt cch lin tc.D. l mt h thng nhng vch sng (vch mu) ring l, ngn cch nhau bi nhng khong ti.

Cu 33:D. Quang ph vch pht x l mt h thng nhng vch sng (vch mu) ring l, ngn cch nhaubi nhng khong ti.Cu 34: Mt on mch AB gm hai on mch AM v MB mc ni tip. on mch AM c in tr

thun 50 mc ni tip vi cun cm thun c t cm1

H, on mch MB ch c tin vi in

dung thay i c. t in p u = U0cos100t (V) vo hai u on mch AB. iu chnh in dung catin n gi tr C sao cho . Gi tr ca C bng1 1

9

A.54.10

F

B.

58.10F

C.

52.10F

D.

510F

2

Cu 34: B. Ta c: ZL = 100 . in p hai u on mch AB lch pha so vi in p hai u on

mch AM 5

L C LAB AM C

C

Z Z Z 1 8.10tan . tan 1 . 1 Z 125 C F

R R Z

= = = = =

.

Cu 35: Mt mch dao ng l tng gm cun cm thun c t cm L khng i v tin c indung C thay i c. iu chnh in dung ca tin n gi tr C1 th tn s dao ng ring ca mchl f . tn s dao ng ring ca mch l th phi iu chnh in dung ca tin n gi tr15f1

A. 1C

51C

5B. C. 5C D.1 15C

1 21 2

1 1

f ;f2 LC 2 LC= = Cu 35: A. Tn s dao ng ring ca mch: .

V 1 12 1 22

C Cf 5f 5 C

5C= = = .

Cu 36: iu kin hai sng ckhi gp nhau, giao thoa c vi nhau l hai sng phi xut pht t haingun dao ng

A. cng bin v c hiu s pha khng i theo thi gianB. cng tn s, cng phngC. c cng pha ban u v cng bin D. cng tn s, cng phng v c hiu s pha khng i theo thi gian

Cu 36: D.iu kin hai sng ckhi gp nhau, giao thoa c vi nhau l hai sng phi xut pht thai ngun dao ng cng tn s, cng phng v c hiu s pha khng i theo thi gian (Hai sng kthp).Cu 37: Mt ht c khi lng ngh m0. Theo thuyt tng i, ng nng ca ht ny khi chuyn ngvi tc 0,6c (c l tc nh sng trong chn khng) l

2A. 0,36m0c B. 1,25 m2

0c C. 0,225m2

0c D. 0,25m0c2

22 20

0 02

2

m cm c 0,25m c

v1

c

=

Cu 37: D. ng nng ca ht ny l:W = = E E0 .

Cu 38: Trong th nghim Y-ng v giao thoa nh sng, ngun sng pht ng thi hai bc xn sc,

trong bc x mu c bc sng 720 nm v bc x mu lc c bc sng (c gi tr trong khongt 500 nm n 575 nm). Trn mn quan st, gia hai vn sng gn nhau nht v cng mu vi vn sngtrung tm c 8 vn sng mu lc. Gi tr ca l

A. 500 nm B. 520 nm C. 540 nm D. 560 nm

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Cu 38: D. Vn sng cng mu vi vn trung tm l v tr vn sng ca hai h vn trng nhau (vn trng).

Khi vn sng ca hai h vn trng nhau: 1 1 2 2 1 11 2 1 1 2 2 22

k D k D k x x k k

a a k

= = = = . Gia hai

vn trng gn nhau nht c 8 vn sng mu lc Vn trng u tin tnh t vn trung tm l vn sng bc

9 ca nh sng lc k 1 1 12 12

k 720k 80k (nm)

k 9

= = =

10

2 = 9. T suy ra: .

V 500 .2 1 1 1 2nm 570nm 500 80k 570 6,25 k 7,19 k 7 560nm = =Cu 39: Mt vt dao ng tt dn c cc i lng gim lin tc theo thi gian l

A. bin v gia tc. B. li v tc .C. bin v nng lng. D. bin v tc .

Cu 39: C. Mt vt dao ng tt dn c cc i lng gim lin tc theo thi gian l bin v nnglng.

Cu 40: Dng mt prtn c ng nng 5,45 MeV bn vo ht nhn ang ng yn. Phn ng to ra

ht nhn X v ht . Ht bay ra theo phng vung gc vi phng ti ca prtn v c ng nng 4MeV. Khi tnh ng nng ca cc ht, ly khi lng cc ht tnh theo n v khi lng nguyn t bngs khi ca chng. Nng lng ta ra trong cc phn ng ny bng

94 Be

A. 4,225 MeV B. 1,145 MeV C. 2,125 MeV D. 3,125 MeVCu 40: C. Phng trnh phn ng: 1 9 .4 61 4 2 3p Be He X+ +

Xp p p= +

nh lut bo ton ng lng: .

V pv v p p

22 2X pp p p= +

X X p p2m K 2m K 2m K = +

p

X

4K K

K 3,575MeV6

+

= = .nh lut bo ton nng lng ton phn:

2 2Be p X X(m m )c K (m m )c K K + + = + + +

2p Be X X pW (m m m m )c K K K 2,125MeV = + = + =

.PHN RING [10 cu]Th sinh chc lm mt trong hai phn (phn A hoc B)A. Theo chng trnh Chun (10 cu, tcu 41 n cu 50)

he c chiu bng nh sng n sc c

D. 2ng:

Cu 41: Trong th nghim Y-ng v giao thoa nh sng, hai k

bc sng . Nu ti im M trn mn quan st c vn ti th ba (tnh t vn sng trung tm) th hiung i ca nh sng t hai khe S1 , S2n M c ln bngA. 2,5 B. 3 C. 1,5

Cu 41: A. M l vn ti khi hiu ng i ca nh sng t hai khe S1 , S2 n M b

2 1

1d d k

2

=

+ . im M trn mn quan st c vn ti th k = 2 d d 2,5M 2 1 = = .

Cu 42: t in p u = U0cost vo hai u cun cm thun c t cm L th cng dng in quacun cm l

A. 0U

i c= os( t )L 2

+

B. 0

Ui cos( t

2L 2)

= +

C. 0Ui cos( tL 2

= ) D.

pp

p

Xp

0Ui cos( t2L 2

)=

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2

Cu 42: C. Cng dng in trong mch ch c cun cm thun tr pha so vi in p hai u mch

0i I cos t 2 =

0 0 0

0L

U U UI i cos

Z L L 2t

= = = .vi

Cu 43: Mt con lc n c chiu di dy treo 50 cm v vt nh c khi lng 0,01 kg mang in tch q =+5.10-6C c coi l in tch im. Con lc dao ng iu ho trong in trng u m vectcng

in trng c ln E = 104 2

V/m v hng thng ng xung di. Ly g = 10 m/s , = 3,14. Chu k daong iu ho ca con lc lA. 0,58 s B. 1,40 s . 1,15 s D. 1,99 sC

F qE=

11

Cu 43: C. Vt nh chu tc dng ca lc in: . Trng lc biu kin tc dng ln vt: P ' P F= +

.

V ; Vq 0 F E> q E

E F F P P ' P F mg ' mg q E g ' g 1m

= + = + = + =

5 m/s2.

Chu k dao ng iu ha ca con lc n trong in trng:0,5

T ' 2 2 1,15sg ' 15

= =

.

Cu 44: Khi chiu chm tia t ngoi vo mt ng nghim ng dung dch fluorexin th thy dung dchny pht ra nh sng mu lc. l hin tng

A. tn sc nh sng B. phn x nh sng C. ho - pht quang D. quang - pht quangCu 44: D. Hin tng quang - pht quang.Cu 45: Vt nh ca mt con lc l xo dao ng iu ho theo phng ngang, mc th nng ti v tr cn

bng. Khi gia tc ca vt c ln bng mt na ln gia tc cc i th t s gia ng nng v thnng ca vt l

A. 3 B.1

C.1

D. 23 2

Cu 45: A. Ta c: 2 2max

2a x ; a A= = = a x . Gia tc ca vt c ln bng mt na ln gia

tc cc i: maxa A

a x

2 2

= = tW

W

4

=3W

4

=

t

W3

W

= .; W

Cu 46: Trong gihc thc hnh, hc sinh mc ni tip mt qut in xoay chiu vi in trR ri mchai u on mch ny vo in p xoay chiu c gi tr hiu dng 380V. Bit qut ny c cc gi trnhmc : 220V - 88W v khi hot ng ng cng sut nh mc th lch pha gia in p hai u qutv cng dng in qua n l , vi cos = 0,8. qut in ny chy ng cng sut nh mc th R

bngA. 180 B. 354 C. 361 D. 267

Cu 46: C. Mch in c th v nh hnh di.

Cng sut nh mc ca qut:

Q

Q Q

P 88I 0,5A

U cos 220.0,8 = = =

Q Q QP U I cos=

Q

.

T gin vect, ta dng nh l hm s csin:2 2 2 2 2

Q R Q R Q R Q R U U U 2U U cos U U 2U U cos= + = + + 2 2 2 2

R R R R 380 220 U 2.220.U .0,8 U 352U 96000 0 = + + + =

RR

UU 180,337 V R 361

I

= =

Cu 47: Ban u c N0 ht nhn ca mt mu cht phng x nguyn cht c chu k bn r T. Sau khongthi gian t = 0,5T, k t thi im ban u, s ht nhn cha b phn r ca mu cht phng x ny l

Q

QutA BN

ABU=

AN QU U

IQ

RU O

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C: 279 Nguyn Tri Phng Qun 10 (T:38575676); 10/5 Trn Nht Dut Qun 1 (T:22405332) TP.HCM 12

A. 02

NB. 0

N

4C. N D. 0

N

220

Cu 47: A. Sau khong thi gian t = 0,5T, s ht nhn cha b phn r:t

0 0T0 0,5

N NN N .2

2 2

= = = .

Cu 48: Trong thng tin lin lc bng sng v tuyn, ngi ta s dng cch bin iu bin , tc l lmcho bin ca sng in t cao tn (gi l sng mang) bin thin theo thi gian vi tn s bng tn s ca

dao ng m tn. Cho tn s sng mang l 800 kHz. Khi dao ng m tn c tn s 1000 Hz thc hin mtdao ng ton phn th dao ng cao tn thc hin c s dao ng ton phn lA. 1600 B. 625 C. 800 D. 1000

Cu 48: C. Tn s ca sng mang gp 800 ln tn s ca sng m tn Chu k ca sng m tn gp 800ln chu k ca sng mang Khi dao ng m tn thc hin mt dao ng ton phn th dao ng cao tnthc hin c 800 dao ng ton phn.

Cu 49: Ti mt im trn mt cht lng c mt ngun dao ng vi tn s 120 Hz, to ra sng n nhtrn mt cht lng. Xt 5 gn li lin tip trn mt phng truyn sng, v mt pha so vi ngun, gnth nht cch gn th nm 0,5 m. Tc truyn sng l

A. 12 m/s B. 15 m/s C. 30 m/s D. 25 m/sCu 49: B. Khong cch t gn sng th nht n gn sng th nm: 4 0,5m 0,125m = =

v f 1 = = 5

Ar

Ar

m/s.

Cu 50: Cho khi lng ca prtn; ntron; ln lt l : 1,0073 u; 1,0087u; 39,9525u; 6,0145u

v 1 u = 931,5 MeV/c

40 618 3Ar ; Li

2. So vi nng lng lin kt ring ca ht nhn th nng lng lin kt ring caht nhn 4018

63 Li

Ar

A. nh hn mt lng l 3,42 MeV B. ln hn mt lng l 5,20 MeVC. ln hn mt lng l 3,42 MeV D. nh hn mt lng l 5,20 MeV

Cu 50:C. Nng lng lin kt v nng lng lin kt ring ca 18 v63 ln lt l:

40 Li

2 lklk p n Ar lkr

WW (18m 22m m )c ; W 8,62MeV

A= + = + Ht nhn 18 :

40 .

2 lklk p n Li lkr

WW (3m 3m m )c ; W 5,20MeV

A= + = + Ht nhn :63 Li .

Nng lng lin kt ring ca ht nhn 18 ln hn nng lng lin kt ring ca ht nhn mtlng l 8,62 5,20 = 3,42 MeV.

40 63 LiAr

B. Theo chng trnh Nng cao (10 cu, tcu 51 n cu 60)

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20CU

2A. Nng lng t trng cc i trong cun cm l

B. Nng lng t trng ca mch thi im t L2

C

=20CU

4l

C. Hiu in th gia hai bn tin bng 0 ln th nht thi im t L2

C

=

D. Cng dng in trong mch c gi tr cc i l 0LUC

Cu 57: B. thi im t = 0, hiu in th gia hai bn t c gi tr cc i l U0. thi im

2 LC Tt LC

2 4

= = =

4, hiu in th gia hai bn t: u = 0 Nng lng in trng bng khng v

nng lng t trng cc i:20

Lmax

CUW W

2= = .

Cu 58: Mt cht im khi lng m, quay xung quanh trc cnh theo quo trong tm O, bn knh

r. Trc qua tm O v vung gc vi mt phng quo. Ti thi im t, cht im c tc di, tc gc, gia tc hng tm v ng lng ln lt v v, , an v p. Momen ng lng ca cht im i vitrc c xc nh bi

A. L = pr B. L = mvr2 C. L = man D. L = mr

Cu 58: A.Momen ng lng ca cht im i vi trc c xc nh: 2v

L I mr mvr pr r

= = = = .

Cu 59: Mt vt rn ang quay u quanh trc cnh vi tc gc 30 rad/s th chu tc dng ca mtmomen hm c ln khng i nn quay chm dn u v dng li sau 2 pht. Bit momen ca vt rnny i vi trc l 10 kg.m2. Momen hm c ln bng

A. 2,0 N.m B. 2,5 N.m C. 3,0 N.m D. 3,5 N.m

0 0,25t = = Cu 59: B. Tc gc: rad/s2; Momen hm: Mhm = I = - 2,5 N.m.

Cu 60: Bit ng v phng x c chu k bn r 5730 nm. Gi s mt mu g c c phng x 200

phn r / pht v mt mu g khc cng loi, cng khi lng ca mu g c, ly t cy mi cht, c phng x 1600 phn r / pht. Tui ca mu g c cho l

146 C

A. 17190 nm B. 2865 nm C. 11460 nm D. 1910 nm

Cu 60: A. phng x ban u v sau thi gian t ca mu g c l: H0 = 1600 phn r/pht; H = 200

phn r/pht. Ta c: t / T 30 0t / T

H HH 2 8 2 t 3T 17190

2 H= = = = = = nm.

Thc s Nguyn Thanh Dng - Thc s Phng Nht Anh (T: 0907575262)

Trung tm BDVH v LTH Thnh Tr

(Nguyn l Trung tm BDVH v LTH trng i hc Kinh t TP. HCM)

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ĐH 2010+giải