Ren Ki Nang Vat Li 112 Danh Cho Gv Va Hs Kha Gioi

Cu 1 ( Cu hi ngn)

Cho on mch gm 5 dy dn ging nhau nh hnh di y. Bit UAB = 12V ; UAC = 7V ; UDB = 8V ; I = 2V ; I1 = 0,9A ; I4 = 0,2A. Tm cng dng in v hiu in th trn mi dy cn li. V chiu dng in chy trong mch.I1 A I R2 D R1 C R3 B R4 I4 I

R5

p n: Ta c UAB = UAC + UCB UCB = UAB UAC = 12 7 = 5V. UAB = UAD + UDB UAD = UAB UDB = 12 8 = 4V. UAC = UAD + UDC UDC = UAC UAD = 7 4 = 3V. -Ti nt A : V I > I1 nn I2 c chiu ri khi nt A. I = I1 + I2 I2 = I I1 = 2 0,9 = 1,1A. -Ti nt B: v I > I4 nn I3 c chiu ri n nt B. I = I3 + I4 I3 = I I4 = 2 0,2 = 1,8A. -Ti nt C: v I3 > I1 nn I5 c chiu ri t D n nt C. I3 = I1 + I5 I5 = I3 I1 = 1,8 0,9 = 0,9A.

I1 A I I2Cu 2 ( Cu hi ngn)

R1 I5

C

R3

I3 B

R5 R2 D R4 I4

I

Tnh s electron i qua tit din thng ca mt dy dn kim loi trong 1s nu c dng in khng i c cng I = 0,5A chy qua.p n:

Ta c: I =

Vq qe qe = 0,5C. = Vt t

in lng ny bng tng ln ca tt c cc electron chuyn qua tit din thng qua dy trong 1s. Ta c: ne = qe e = 0 ,5 = 3,125.1018 electron. 1 ,6.10- 19

Cu 3 ( Cu hi ngn)

Trong mt dy dn kim loi c dng in khng i, cng I = 0,96A chy qua . Bit tit din ca dy l 0,6mm2. Tm a)Mt dng in qua dy dn. b)S electron i qua tit din ngang ca dy trong 10s.p n:

a) j = 1,6.106A/m2 b) n = 6.1019.Cu 4 ( Cu hi ngn)

Mt dng in khng i c cng I = 4,8A chy qua mt dy kim loi c tit din thng S = 2cm2. Tnh: a)S electron chuyn qua tit din thng ca dy trong 3s. b) Vn tc trung bnh ca chuyn ng c hng ca electron. Bit mt electron t do l n = 3.1028m-3 (ht/m3).p n:

a) n = 9.1019. b) I = neSv v = 5.10-6V/m.Cu 5 ( Cu hi ngn)

Trong khong thi gian t = 10s, cng dng in qua dy dn tng u t I1 = 1A n I2 = 4A. Tnh cng dng in trung bnh v in lng chuyn qua dy dn trong thi gian trn.p n:

Itb = 2,5A ; q = 25C.Cu 6 ( Cu hi ngn)

Mt ngun in c sut in ng 10V. Khi mc ngun in ny thnh mch in kn th n cung cp mt dng in c cng l 0,8A. Tnh cng ca ngun in ny sinh ra trong thi gian 5 pht.p n:

A = UIt = 24000 J.Cu 7 ( Cu hi ngn)

Mt in lng 8mC dch chuyn qua tit din thng ca mt dy dn trong thi gian 2,5s. tnh cng dng in chy qua dy dn ny.p n:

I = 3,2 mA.Cu 8 ( Cu hi ngn)

Bn vt dn c ni vi cc dy dn nh hnh v.

A

I

I1

R1

M

R2 N I3 R3

R4

I

B

UAB = 12V ; UAM = 8V ; I = 6A ; I1 = 3A ; I3 = 5A. Tm cng dng in v hiu in th trn mi vt dn cn li.p n:

I2 = 2A ; I3 = 5A ; I4= 1A ; U1 = U2 = 8V ; U4 = 12V ; U3 = 4V.Cu 9 ( Cu hi ngn)

n 220V 100W c mc vo ngun U = 220V. in tr tng cng ca dy dn t ngun n n l R = 16 . a)Tm cng dng in chy qua v hiu in th gia hai u bng n. b) Mc thm mt bp in c in tr l RB = 46 song song vi n. Tm cng dng in qua mch chnh, qua n, qua bp v hiu in th ca n. sng ca n c thay i khng ?

p n:

a) in tr ca n l:

R =

= 220 = 484 100 = 220 = 0,44A 484 + 16

2

Cng dng in trong mch: I =

Hiu in th ca n: U = IR = 0,44.484 = 212,96V b) Mch in c cu trc (R // RB) nt R R,B = = 484.46 42 484 + 46

Rt = R + R, B = 16 + 42 = 58 Cng dng in trong mch chnh: I = Hiu in th hai u n v bp: U = UB = U,B = I.R,B = 3,8.42 = 159,6V. Cng dng in qua n: I = Cng dng in qua bp: IB = ,6 = 159 = 0,33A. 484 ,6 = 159 = 3,47A 46 = 220 = 3,8A. 58

Khi mc thm bp in vo mch, cng dng in mch chnh tng nn gim th trn ng dy tng. Do hiu in th hai u bng n gim, do sng ca n s gim.Cu 10 ( Cu hi ngn)

Mt bp in c hai dy in tr. Nu s dng dy th nht un th nc trong ni s si sau thi gian t1 = 10 pht. Nu s dng dy th hai th thi gian un l t2 = 40 pht. Tm thi gian un si nc nu hai dy in tr mc: a)Ni tip b) Song song. B qua s ta nhit ca bp ra mi trng bn ngoi.p n:

Gi hiu in th ca ngun cung cp l U. Nhit lng cn cung cp un si nc l Q. in tr cc bp l R1, R2 Khi dng dy c in tr R1 : Q = U2 t1 R1 (1)

Khi dng dy c in tr R2 : Q = a)Mc ni tip: Khi dng dy R1 ni tip R2 : Q =

U2 t2 R2

(2)

U2 t3 R1 + R2

(3)

T (1) v (2) suy ra:

t1 t t +t = 2 = 1 2 so snh vi (3) ta c: R1 R2 R1 + R2

t3 = t1 + t2 = 10 + 40 = 50 pht b) Mc song song : Khi dng dy R1 // R2 : Q = T (4) ta c : 1 U2 1 1 U2 U2 1 1 = ( + )= + = + t4 Q R1 R2 QR 1 QR 2 t1 t2 t4 = t1.t2 10.40 = = 8 pht. t1 + t2 10 + 40 U 2(R1 + R2) t1 R1.R2 (4)

Cu 11 ( Cu hi ngn)

Mt ngun in c sut in ng l 10V. Khi mc ngun in ny vo mch in th n cung cp dng in c cng l 0,8A. Tnh cng ca ngun in ny sinh ra trong thi gian 5 pht v tnh cng sut ca ngun in khi .p n:

A = Cit = 24000J ; P = C.I = 8WCu 12 ( Cu hi ngn)

Mt bp in tiu th cng sut

= 1,1kW khi c dng mng in c hiu in th U = 120V.

Dy ni t cm vo bp in c in tr tng cng r = 1 . a)Tnh in tr R ca bp in. b) Tnh nhit lng ta ra bp in khi s dng lin tc bp in trong thi gian na gi.p n:

a) R = 11 b) Q = RI2t = 19,8.105J.Cu 13 ( Cu hi ngn)

Mt my pht in cung cp in cho mt ng c hot ng. Sut in ng v in tr trong ca my l

C ; r = 1 . Dng in chy qua ng c l I = 2A, in tr tng cng ca cc cun dy

trong ng c l R = 1,5 . Hy tnh: a)Cng sut ca ngun in v hiu sut ca n. b) Cng sut in tiu th ton phn v cng sut c hc (c ch) ca ng c in. Hiu sut ca ng c.p n:

a)

P = C.I = 50W ; U = 23V H = 92%. P1 = UI = 46W. P2 = C.I = 40W.

b) Cng sut in tiu th ton phn ca ng c : Cng sut c hc ca ng c :

Hiu sut ca ng c : H = 87%.Cu 14 ( Cu hi ngn)

Bp in c cng sut

P = 600W c dng un si 2 lt nc t 200C n 1000C. Hiu sut

ca bp l 80%. Nhit dung ring ca nc l c = 4200J/kg.. Tm thi gian un v in nng tiu th ra kWh.p n:

t = 23pht 20 giy ; A = 0,23kWh.Cu 15 ( Cu hi ngn)

Ngi ta dng mt m in bng nhm c khi lng m1 = 0,4kg un mt lng nc m2 = 2kg th sau 20 pht nc s si. m in c hiu sut H = 60% v c dng mng in c hiu in th U = 200V. Nhit ban u ca nc l t1 = 200C, nhit dung ring ca nhm l c1 = 4200J/kg.. Tm nhit lng cn cung cp cho m nc v cng dng in chy qua bp.p n:

Q = 700160J ; I = 4,42A.Cu 16 ( Cu hi ngn)

Dng m in loi 200V 1000W un si 2 lt nc t 200C. m in nng 500g. Cho cnc =4200J/kg. ; cnhm = 880J/kg.. Tnh thi gian un si nc trong hai trng hp : a)Hiu in th ca ngun U = 220V. b) hiu in th ca ngun U = 180V.p n:

a) t = 11 pht 47 giy.

b) t = 17pht 36 giyCu 17 ( Cu hi ngn)

T mt ngun in c hiu in th U, in nng c truyn trn dy dn ti ni tiu th. Bit in tr dy dn l R = 5 , cng sut ca ngun in l P = 62kW. Tm gim th trn dy, cng sut hao ph v hiu sut ti in nu : a)U = 6200V. b) U = 620V.p n:

a) U = 50V ;

P = 500W ; H = 99,2%. P = 50000W ; H = 19,35%.

b) U = 500V ;

Cu 18 ( Cu hi ngn)

C hai loi n 120V 60W v 120V 45W a)Tm in tr v cng nh mc ca mi n. b)Mc hai n theo mt trong hai cch nh hnh di y. Khi UAB = 240V th c hai n u sng bnh thng. Tm r1 , r2. Cch mc no c li hn ?

p n:

a) R1 = 240 ; I1 = 0,5A ; R2 = 320 ; I2 = 0,375A. b) r1 = 137 ; r2 = 960 . Cch mc 1.

Cu 19 ( Cu hi ngn)

C th mc ni tip hai n loi (120V 100W) v (6V 5W) vo ngun U = 120V c khng ? Ti sao ?p n:

c v I1 , I2 < IMCu 20 ( Cu hi ngn)

mc n vo ngun c in th cao hn in th nh mc ghi trn n , ta c th dng mt trong hai s sau:

S no c hiu sut cao hn ? Bit trong hai trng hp n sng bnh thng.p n:

S 2 c hiu sut cao hn.Cu 21 ( Cu hi ngn)

C 3 bng n, hiu in th nh mc ca mi bng n l 110V c mc vo ngun 220V nh hnh v.

Tm h thc lin h gia cc cng sut nh mc sng bnh thng.p n:

P1 , P-2, P3 ca cc bng n chng u

I +I = I 1 2 3 U 1 = U 2 = U 3 = 110 V

P 1 = P -2 = P 3

Cu 22 ( Cu hi ngn)

Mt my bm in hot ng vi hiu in th U = 360V v cng dng in I = 25A, bm nc ln cao h = 4m qua mt ng c tit din S = 0,01m2, mi giy c 80 lt. a)Tnh hiu sut ca my bm. Cho g = 10m/s2. b) Gi s ma st lm tiu hao 20% cng sut ca ng c v phn cng sut hao ph cn li do hiu ng Jun len x . Hy tnh in tr trong ca ng c.p n:

a) H = 35,56% ; b) R = 6,4Cu 23 ( Cu hi ngn)

Cho mt on mch nh hnh v di y . Bit rng R1 = 1 ; R2 = 20 ; R3 = 5 ; R4 = R5 = 10 . Hy tnh in tr tng ng ca on mch.

R1 = 1 ; R2 = 20 ; R3 = 5 ; R4 = R5 = 10 Tnh RAB = ?p n:

Cch mc in tr : [R1 nt (R2 // R3)] // [R4 nt R5] R23 = R2.R3 20.5 = 4 ; R123 = R1 + R2 = 1 + 4 = 5 . = R2 + R3 20 + 5 R123.R45 5.20 = = 4 R123 + R45 5 + 20

R45 = R4 + R5 = 10 + 10 = 20 ; RAB =

Vy in tr tng ng ca on mch l 4 .Cu 24 ( Cu hi ngn)

Tnh in tr tng ng ca mch in di y, bit cc in tr c gi tr bng nhau v bng R.

p n:

V li mch in :

-Cu trc mch : R1 // [R4 nt (R2 // R3)] R23 = R2.R3 R.R R . = = R2 + R3 R + R 2

R234 = R4 + R23 = R + R = 3R 2 2 3R R234.R1 2 = 3R Rt = = 3R R234 + R1 5 R+ 2 R.Cu 25 ( Cu hi ngn)

Cho mch in nh hnhv .

R1 = 2 ; R2 = 3 ; R3 = 4 ; R4 = 6 ; UAB = 18V. a)Tm RAB . b) Tm cng dng in chy qua cc in tr v hiu in th trn mi in tr.p n:

a) RAB = 3,6 b) I1 = 3A ; I2 = 2A ; I3 = 3A ; I4 = 2A ; U1 = U2 = 6V ; U3 = U4 = 12V.Cu 26 ( Cu hi ngn)

Cho mch in nh hnh v.

R1 = 5 , R2 = 7 ; R3 = 1 , R4 = 5 , R5 = 3 , UAB = 21V. a)Tnh RAB . b) Tm cng dng in qua cc in tr .p n:

a)RAB = 3,5 b) I1 = 3A ; I2 = 3A ; I3 = I4 = 1A ; I5 = 2A; U1 = 15V ; U2 = 21V ; U3 = 1V ; U4 = 5V ; U5 = 6V.Cu 27 ( Cu hi ngn)


Cho bit : R1 = 4 , R2 = R5 = 20 ; R3 = R6 = 12 , R4 =R7 = 8 , UAB = 48V.

a)Tnh RAB . b) Tm cng dng in v hiu in th ca mi in tr.p n:

a) RAB = 16 . b) I1 = I2 = 0,17A ; I3 = 0,33A ; I4 = 0,5A ; I5 = 1A ; I6 = 2A ; I7 = 3A.Cu 28 ( Cu hi ngn)


R1 = R3 = 3 ; R2 = 2 , R4 = 1 ,R5 = 4 , cng dng in qua mch chnh l I = 3A. Tm : a)UAB v hiu in th ca mi in tr. b) UAD , UED.p n:

a) UAB = 18V ; U1 = U3 = 3V ; U2 = 4V ; U4 = 2V ; U5 = 12V b) UAD = 15V , UED = -1V.Cu 29 ( Cu hi ngn)

Cho mch in nh hnh v : R1 = R3 = R5 = 1 , R4 = 2 , R3 = 3 .

a)Tnh RAB. b) I4 = 1A. Tnh dng in qua cc in tr v UAB.p n:

a) RAB = 1,5 b) I1 = 3A ; I2 = 1A ; I3 = 1A ; I5 = 3A , UAB = 7,5VCu 30 ( Cu hi ngn)


UAB = 6V. Khi K m ampe k A1 ch 1,2A. Khi K ng, ampe k A1, A2 ch ln lt 1,4A v 0,5A. B qua in tr ca cc ampe k. Tnh R1, R2, R3.p n:

R1 = 3 , R2 = 2 , R3 = 3,6 .Cu 31 ( Cu hi ngn)


Cho bit R1 = 15 , R2 = R3 = R4 = 10 . in tr ca ampe k v cc dy ni khng ng k . a)tm RAB. b) Bit ampe k ch 3A. Tnh UAB v cng qua cc in tr.p n:

a) RAB = 7,5 . b) UAB = 36V ; I1 = 1,2A ; I2 = 3,6A ; I3 = I4 = 1,8A.Cu 32 ( Cu hi ngn)


Bit R1 = 4 , R2 = 6 , R3 = 12 , UAB = 6V in tr ca dy ni v ca ampe k khng ng k. Tnh s ch ca ampe k khi : a)K1 m, K2 ng. b) K1 ng, K2 m c) K1, K2 u m d) K1, K2 u ng.p n:

a) A, A2 ch 1,5A ; A1 ch 0 b) A ch 5/12 = 4,2A ; A1 ch 1/6A ; A2 ch 0

c) A ch 3/11 = 0,2A ; A1 ch 0A ; A2 ch 0. d) A ch 3A ; A1 ch 1,5A ; A2 ch 2,5A.Cu 33 ( Cu hi ngn)


Cho bit : R1 = R2 = R3 = R4 = R5 = 10 , UAB = 30V. in tr ca ampe k v cc dy ni khng ng k a)Tm in tr RAB ca on mch b) Tm cng dng in qua cc in tr v ch s ca ampe k.p n:

a)RAB = 6 b) I1 = 2A ; I2 = 3A ; I3 = I4 = 1A ; IA = 4A.Cu 34 ( Cu hi ngn)

Cho mch in nh hnh v

Chng minh rng : Nu

R1 R3 = th R2 R4

a)Khi K ng hay m, in tr tng ng ca on mch AB khng thay i. b) Hiu in th gia hai im C v D bng 0.p n:

a) Ta c :

R1 R2 R + R2 R R R + R3 = = 1 v 1 = 3 = 1 R3 R4 R3 + R4 R2 R4 R2 + R4 (R1 + R3)(R2 + R4) = R1 + R2 + R3 + R4 (R1 + R3)2. R2 R1 R2 R1 (R1 + R3).R2 R1 + R2

K m: RAB =

=

(R1 + R3) + (R1 + R3).

R1.R2 R .R R .R R3.R4 R (R + R4) + 3 4 = 1 2 + = 1 2 K ng : RAB = R1 + R2 R3 + R4 R1 + R2 R3 (R1 + R2) .(R1 + R2) R1 RAB = R1. R2 (R + R3) R1 1 R (R + R3) = RAB (pcm) = 2 1 (R1 + R2) (R1 + R2)

b) K ng : UCD = U1 U2 = 0 K m : UCD = U1 U2 = R1.I1 R2.I2 M I 1 R1 + R3 R1 = = I2.R2 = I1.R1 nn UCD = 0. I 2 R2 + R4 R2

Cu 35 ( Cu hi ngn)


Cho bit R1 = 2 , R2 = R4 = 6 , R3 = 8 , R5 = 18 , UAB = 6V. a)tm in tr RAB ca on mch b) Tm cng dng in qua cc in tr v s ch ca ampe k.p n:

Hng dn : Mch cu ny cn bng. a)Tm RAB = 6 b) I1 = I4 = 0,75A ; I2= I5 = 0,25A ; I3 = IA = 0.

Cu 36 ( Cu hi ngn)

Cho mch in nh hnh v

Cho bit R1 = 2 , R2 = 10 , R3 = 6 , UAB = 24V. in tr ca vn k rt ln. a)Vn k ch s khng. Tnh R4. b) iu chnh R4 vn k ch 2V. Tm gi tr ca R4 khi . Cc dng ca vn k ni vi im no.p n:

a) R4 = 30 . b) UCD = 2V th R4 = 18 UDC = 2V th R4 = 66 .Cu 37 ( Cu hi ngn)


Cho bit: R1 = 15 , R2 = 30 , R3 = 45 , UAB = 75V. in tr ca ampe k nh khng ng k. a)Cho R4 = 10 th ampe k ch bao nhiu ? b) iu chnh R4 ampe k ch s khng. Tnh tr s R4 khi .p n:

a) IA = 2A.

b) R4 = 90 .Cu 38 ( Cu hi ngn)


Cho bit: R1 = 4 , R2 = 2 , R3 = 8 , R4 = 4 , R5 = 2,4 , R6 = 4 , UAB = 48V. in tr ca ampe k v cc dy ni khng ng k. Tm s ch ca ampe k khi. a)K m b) K ng.p n:

a) A1 ch 0 ; A2 ch 0,48A. b) A1 ch 20A ; A2 ch 12A.Cu 39 ( Cu hi ngn)

Cho mch in nh hnh v:

Cho bit R1 = 21 , R2 = 42 , R3 = R4 = R6 = 20 , R7 = 20 , UAB = 33V, in tr ca vn k rt ln. a)tm ch s ca vn k. b) Thay vn k bng ampe k (RA = 0). Tm ch s ca ampe k.

p n:

a) 7,5V ; b) 0,404A.Cu 40 ( Cu hi ngn)

Mch kn gm ngun in c sut in ng

C = 200V v in tr trong 0,5 v hai in tr

R1 = 100 ; R2 = 500 mc ni tip. Mt vn k mc song song vi R2 , c s ch 160V . Tm in tr ca vn k.p n:

Mch in nh hnh v :

in tr mch ngoi : R= R2RV R2 + RV + R1 R2RV + R1 + r R2 + RV

in tr ton mch bng Rt- = R + r = Cng dng in trong mch S ch vn k : UV = I Vy ta c: 160 = Thay s R2RV R2 + RV I=

R2RV = 402 RV = 2051 R2 + RV

Cu 41 ( Cu hi ngn)

Hai in tr R1 = 2 ; R2 = 6 mc vo ngun (

C, r) . Khi R1 ni tip vi R2 , cng trong

mch l I = 0,5A. Khi R1 song song vi R2 cng trong mch chnh l I = 1,8A. Tm C, r ?p n:

- Khi R1 nt R2 : in tr ton mch R = R1 + R2 + r I = = 0,5 = (1)

-Khi R1 // R2 : in tr ton mch : R = R1R2 + r I = R1 + R2 1,8 = 1,8 = (2)

T (1) v (2)

C = 4,5 ; r = 1 . C1 = 25V ; C2 = 16V, r1 = r2 = 2 ;

Cu 42 ( Cu hi ngn)

Cho mch in c cu to nh s nh hnh v.

R1 = R2 = 10 ; R3 = R4 = 5 ; R5 = 8 . Tnh cng dng in qua mi in tr.

p n:

Gi s cc dng in c chiu nh hnh v. Chn chiu dng nh hnh v

-Cc phng trnh nt : I = I1 + I5 = I3 + I4 I1 = I2 + I3 I4 = I2 + I5 - Cc phng trnh mt mng : (1) (2) (3)

C2 + R1I1 + R3I3 + r2I = 0 10I1 + 5I3 + 2I = 16 C1 C2 + (R5 + r1)I5 + R4I4 + r2I = 0 10I5 + 5I4 + 2I = 41

(4) (5) (6) (7)

0 = R2I2 + R4I4 R3I3 10I2 + 5I4 5I3 = 0 Ly (4) + (5) ta c 4I + 10(I1 + I5) + 5(I3 + I4) = 57 Kt hp (7) vi (1) ta c : 19I = 57 I = 3A. Kt hp (6), (1) v (2) ta c :

10(I1 I3) + 5(I I3) 5I3 = 0 10I1 20I3 + 5I = 0 2I1 4I3 = - 3 (8) T (4) ta li c : 10I1 + 5I3 + 6 = 16 2I1 + I3 = 2 Ly (9) (8) ta c : 5I3 = 5 I3 = 1A. Thay vo (9) ta c : I1 = 0,5A. (1)I5 = I I1 = 3 0,5 = 2,5A. (2) I2 = I1 I3 = 0,5 1 = - 0,5A Chiu dng in ngc li. (3) I4 = I2 + I5 = - 0,5 + 2,5 = 2A.Cu 43 ( Cu hi ngn)

(9)

Mt ngun in c sut in ng

C v in tr trong r . Mc vo hai cc ca ngun mt bin.

tr. Tm gi tr ca bin tr cng sut tiu th mch ngoi cc i.p n:

Pmax khi R = r. Khi Pmax =Cu 44 ( Cu hi ngn)

Ngun in c

C = 12V, r = 2 . Mch ngoi l cc n loi 3V 3W mc hn hp i xng .

Xc nh s bng n v cch mc chng chng sng bnh thng.p n:

Mi bng n c in tr v cng dng in nh mc l : R0 = 3 ; I = 1A. Cch mc cc n : mc thnh m dy, mi dy c n n (m, n 1 ; m , n Khi I = m.I0 = m ; R = nR 0 3n = m m 2n + 3m = 12 m = 12 - 3n (*) 2 N).

Mt khc : I =

12 nn m = 3n 2+ m

10 m1 n n = 1, 2, 3 thay vo (*) ta c n = 4,5 ; 3 ; 1,5 3 Vy m = 2 ; n = 3.Cu 45 ( Cu hi ngn)

Cho mch in nh hnh v :

C = 7,8V , r = 0,4 , R1 = R2 = R3 = 3 , R4 = 6 .a)tm dng in qua cc in tr. b) Hiu in th gia hai cc ca ngun. c) Cng sut tiu th trn on mch AB v ca ngun in.

p n:

a)I1 = I3 = 1,17A ; I2 = I4 = 0,78A. b) UAB = 7,02V. c)

P = 12,689W, C1 = 9V ; C 2 = 3V ; C3 = 10V; r1 = r2 = r3 = 1 ; R1 = 3 ;

Cu 46 ( Cu hi ngn)


R2 = 5 ; R3 = 36 ; R4 = 12 .

a)Xc nh ln v chiu dng in qua mch chnh. b)Cho bit u l ngun in, u l my thu.p n:

a) I = 0,1A chiu dng in l chiu ngc chiu kim ng h b)

C1, C2 l my pht , C3 l my thu.

Cu 47 ( Cu hi ngn)


Cc in tr u c gi tr nh nhau v bng R. Ngunp n:

C = 12V ; r = R. Tnh hiu in th UAB.

Hng dn : V mch i xng nn M v N cng in th. Do ta c th chp M v N. V li mch ta tnh c : UAB = 7V.Cu 48 ( Cu hi ngn)

Cho mch in nh hnh v

R1 = R2 = R3 = 40 ; R4 = 30 ; r = 10 ; RA = 0 ; IA = 0,5A. a)Tm sut in ng ca ngun

C.

b) i ch ampe k v ngun. Tm IA .p n:

a)

C = 18V ;

b) IA = 0,5a.Cu 49 ( Cu hi ngn)

Cho mch in nh hnh v

r = 0,5 ; R1 = R4 = 1 ; R2 = R3 = 3 ; R5 = 2,5 . Khi K ngt vn k ch 1,2V ; khi K m vn k ch 0,75V. Tm sut in ng ca ngun v in tr R6.p n:

C = 6V ; R6 = 2 .Cu 50 ( Cu hi ngn)


C = 6V ; r = 1 , R1 = 1 ; R2 = R3 = 3 . Khi K ng Ampe k ch I1 , khi K m ampe k chI2 v I1 = a)Tm R4. b)Cng dng in qua kha K khi K ng.p n:

9 I2 5

a) R4 = 15 b) 7,5A.Cu 51 ( Cu hi ngn)

Ngun

C = 36V ; r = 4 thp sng N = 36 bng n loi 3V 3W. Pmax v hiu sut

a)C bao nhiu cch mc cho 36 bng n c cng sut tiu th nh nhau. b) Cch mc no 36 bng n sng bnh thng ? c) Cch mc no cng sut tiu th trong mi bng n l ln nht. Tnh tiu th ca mch lc . Gi thit khng bng no chy.p n:

a) Mc i xng m dy, mi dy gm n n . Khi I = mI ; in tr mi n l R0 = 3 nR 0 3n ;I= = m m I = 24 m + 3n

Ta c : I I0 (cng dng in nh mc ca mi n) ; I0 = 1A.

24 1 m + 3n 24 m m.n = 36 nn ta c m + 3n m 36 18 36 24 m2 24m + 108 0 ; 6 m m

M + 3.

V n N nn m phi l s chn (vi m > 1). b) 36 bng n sng bnh thng khi I = I0 = 1A m = n = 6. c) m = n = 6 ;

Pmax = 108W ; H = 75%.

Cu 52 ( Cu hi ngn)

Ngun c

C = 24V ; r = 6 , cc bng n loi 6V 3W.

a)C th mc ti a bao nhiu bng n v mc nh th no chng sng bnh thng. b)Nu ch c 6 bng n , mc chng nh th no chng sng bnh thng ? Cch mc no c li hn ?p n:

a) Mc ti a 8 bng thnh 2 dy, mi dy gm 3 n. b) C 2 cch: mc thnh 2 dy v mi dy gm 3 n v cch mc 6 n song song. Cc mc 1 c li hn v khi hiu sut ca ngun ln hn.Cu 53 ( Cu hi ngn)

Cho mch in nh hnh v

C = 150V ; r = 4R ; RV1 = RV2 . Vn k V1 ch 110V. Tm s ch ca vn k V2. 15p n:

10V.Cu 54 ( Cu hi ngn)

Cho mch in nh hnh v

a)Tm hiu in th gia hai u ca R v r bit khi K ngt, K ng cng sut tiu th mch ngoi khng i b) Chop n:

C = 24V . Tnh UAB khi K ng v khi K ngt.5 ; 3

a) r =R.

b) K m : UAB = 13,52V ; K ng ; UAB = 10,48V.Cu 55 ( Cu hi ngn)

Cho mch in nh hnh v

C = 120V ; r = 5 ; R1 = 15 ; R2 = 10 ; R3 = R4 = 20 ; C = 0,2F.

Khi K ngt th vn k ch UV = 60V. a)K ng, tm UV v IK. b) Tnh in tch ca t in khi K ng v K ngt.p n:

a) K ng : UV = 72V v IK = 2,4A. b) Khi K m : Q = 6C v khi K ng : Q = 7,2C.Cu 56 ( Cu hi ngn)

Cho mch in nh hnh v

C = 7,2V , r = 2 . R1 = R2 = R3 = 3 ; C = 0,4F ; RA = 0. Khi K ng th IA = 0,36A.a)Tnh IA khi K ngt b) IK khi K ng. c) in tch ca t khi K ngt, K ng.p n:

a) R4 = 3A IA = 1A. b) IK = 1,44A. c) K ngt : Q = 0,8C, K ng Q = 0,72C.Cu 57 ( Cu hi ngn)

Mch kn gm ngun in (

C = 200V , r = 0,5 ) v hai in tr mc ni tip R1 = 100 ;

R2 = 500 . Mt vn k mc song song R2 ch 160V. Tnh in tr ca vn k.

p n:

RV = 2051 .Cu 58 ( Cu hi ngn)

Cho mch in nh hnh v:

Mi pin c e = 1,5V , r0 = 1 , R = 12 . Tm cng dng in mch chnh v hiu in th hai u in tr.p n:

-Cu trc b ngun : [(4 pin ni tip) // (4 pin ni tip)] ni tip 2 pin. 4r eb = 4e + 2e = 4e = 4.1,5 = 6V ; rb = 0 + 2r0 = 4r0 = 4.1 = 4 . 2 2 -p dng nh lut m cho ton mch ta c: I= eb 6 = = 0,375A. R + rb 12 + 4

-Hiu in th hai u in tr : U = RI = 12.0,375 = 4,5V.Cu 59 ( Cu hi ngn)

Cho 2 mch in nh hnh v : Ngun in in

C1 c C1 = 18V, in tr trong r1 = 1 . Ngun

C2 c sut in ng C2 v in tr trong r2 . Cho R = 9 ; I1 = 2,5A ; I2 = 0,5A. Xc C2 v in tr r2.

nh sut in ng

p n:

-p dng nh lut m cho ton mch +Mch 1:

C1 + C2 = I1(R + r1 + r2)

18 +

C2 = 2,5(9 + 1 + r2)(1)

C2 = 2,5r2 + 718

+Mch 2:

C1 C2 = I2(R + r1 + r2)

C2 = 0,5(9 + 1 + r2)(2)

C2 = -0,5r2 + 13

T (1) v (2) ta c : 2,5r2 + 7 = - 0,5r2 + 13 r2 = 2 . Thay vo (1) ta c : -Vy (

C2 = 2,5.2 + 7 = 12V.

C2, r2) = (12V, 2 ).

Cu 60 ( Cu hi ngn)

Mt ng c in nh, c in tr trong r = 2 . Khi hot ng bnh thng cn mt hiu in th U = 9V v mt dng in cng I = 0,75A. a)Tnh cng sut tiu th ca ng c v hiu sut ca ng c.

b) cung cp in cho ng c , ngi ta dng 18 acquy, mi ci c sut in ng

C = 2V,

in tr trong r = 2 . Hi phi mc cc acquy nh th no hiu sut ca b acquy l ln nht.p n:

a) Cng sut ton phn ca ng c

P = UI = 6,75W (Cng sut dng in cung cp cho ng c).

Cng sut hao ph do ta nhit in tr trong ca ng c :

P = I2r = 1,125W.Vy hiu sut ca ng c H = = 83,3% b) Gi s 18 acquy trn c mc thnh n dy mi dy gm m ngun, m.n = 18 Sut in ng b ngun

Cb = mC = 2mmrb 2m = n n

in tr trong b ngun rb =

Vy hiu in th b ngun cung cp cho ng c l : U = 9 = 2m 0,75. 2m 0 m ,75 9 = 2m(1 ) n 18

Cb Irb

m = 18 n = 1 81 = m(18 0,75m) m = 6 n = 3 m = 18 -Vi th hiu sut H = n =1 m=6 -Vi th hiu sut H = n =3 = = 9 = 25%. 36

9 = 75%. 12

Vy hiu b acquy l ln nht th mc thnh 3 dy, mi dy gm 6 acquy.Cu 61 ( Cu hi ngn)

C 12 ngun ging nhau

C = 1,5V ; r = 3 .

a)C bao nhiu cch mc chng thnh b i xng. Tm sut in ng v in tr trong ca b ngun . b) Nhng b ngun ni trn u c ln lt ni vi in tr R = 6 . -B ngun no cho cng sut tiu th trn R l ln nht. Tnh

Pmax

-B ngun no cho cng sut tiu th trn R l nh nht. Tnhp n:

Pmax

a) Mc thnh b gm m dy, mi dy gm n ngun. Ta c: m.n = 12 ; m, n N ; m n 1 12 18 36 3/7

Cb = nC = 1,5n ; rb = nr = 3n ; I = m m2 6 9 9 0,6 3 4 6 4 0,6 4 3 4,5 2,25 6/11 6 2 3 1 3/7 12 1 1,5 0,25 0,24

Cb (V)rb ( ) I(A)

b) B ngun (m, n) = (2, 6) ; (3,4) cho cng sut tiu th trn R l ln nht. B ngun (m, n) = (12,1) cho cng sut tiu th trn R l nh nht.Cu 62 ( Cu hi ngn)

Pmax = 2,16W.

Pmin = 0,3456W.

C 80 pin (1,5V, 1 ) , mch ngoi c in tr R. Xc nh cch mc ngun thnh b i xng cng sut mch ngoi cc i. tnh a)R = 5 b) R = 6 .p n:

Pmax trong cc trng hp.

Pmax Imax m =

N .r R

a) R = 5 ; m = 4 ; n = 20 ;

Pmax = 45W.

b) R = 6 ; m = 3,65 m = 3, 4 n = 80/3 ; 20. Vy (m, n) = (4, 20) Cu 63 ( Cu hi ngn)

Pmax = 44,6W

cho mch in nh hnh v

C = 2V ; r = 1 ; R1 = 1 ; R2 = 12 ; R3 = 6 ; R4 = 2 ; C = 0,8F.a)Tnh

Cb , rb.

b) Tnh IA , UV. c) Tnh q ca t.p n:

a)

Cb = 4V ; rb = 1 .

b) IA1 = 0,33A, IA2 = 0,5A ; UV = 1,25V. c) q = 2.10-6CCu 64 ( Cu hi ngn)

C n acquy (

C, r) ging nhau ni vi in tr mch ngoi R. Tm iu kin cng qua R

khi n acquy mc ni tip hoc song song u nh nhau.p n:

R = r.Cu 65 ( Cu hi ngn)

c 6 ngun in (

C = 3V ; r = 0,5 ) c mc thnh b ri ni vi mch ngoi c R = 1,5 th P = 24W. Hi cc ngun c mc nh th no.

cng sut mch ngoi

p n:

(m, n) = (1, 6) ; (2, 3).Cu 66 ( Cu hi ngn)

Mt ng c in nh, c in t trong r = 2 . Khi hot ng bnh thng cn mt hiu in th U = 9V v mt dng in cng I = 0,75A. a)Tnh cng sut tiu th ca ng c v hiu sut ca ng c. b) cung cp in cho ng c , ngi ta dng 18 acquy, mi ci c sut in ng

C = 2V

in tr trong r = 2 . Hi phi mc cc acquy , nh th no hiu sut ca b acquy l ln nht.p n:

a)

P = 6,75W ; H = 83,3%;

b) (m, n) = (6, 3) ; Hmax = 75%.Cu 67 ( Cu hi ngn)

Cho mch in nh hnh v

Cb = 42,5V ; rb = 1 , R1 = 10 ; R2 = 15 . in tr ca ampe k, ca cc dy ni khngng k a)Bit rng b ngun gm cc pin ging nhau mc theo kiu hn hp i xng , mi pin c sut in ng b = 1,7V ; rb = 0,2 . Hi b ngun gm bao nhiu dy song song, mi dy gm bao nhiu pin. b) Bit s ch ampe k A1 ch 1,5A . hy xc nh ch s ca A2 v tr s ca in tr R.p n:

a) 5 dy, mi dy 25 pin ; b) A2 ch 1A ; R = 10 .Cu 68 ( Cu hi ngn)

C ba ngun (

C; r) c mc vi nhau nh hnh v.

Hy tnh hiu in th gia hai u mi ngun.p n:

Cb = 3C ; rb = 3r ; U = 0.Cu 69 ( Cu hi ngn)

Cho 7 ngun in ging nhau

c

C = 6V ; r = 2 ; R1 = 3 ; R2 = 6 ; R3 = 2 ; RA = 0. Tm ch s ca ampe k. 3

p n:

IA = 7,2A.Cu 70 ( Cu hi ngn)

Cho mch in nh hnh v

Cho bit

C1 = 1,9V ; C2 = 1,7V ; C3 = 1,6V ; r1 = 0,3 ; r2 = r3 = 0,1 . Ampe k ch 0.

Tnh in tr R v dng in qua cc mch nhnh.p n:

R = 0,8 ; I = 2A ; I1 = I2 = 1A.Cu 71 ( Cu hi ngn)

Biu thc I =

q c dng xc nh t

A: gi tr tc thi ca cng dng in . B: gia tr trung binh ca cng dng in trong khong t . C: gi tr ca cng dng in khng i. D: gi tr tc thi ca cng dng in khi l dng in mt chiu.p n ng: B Cu 72 ( Cu hi ngn)

C ng thi c ion m v ion dng chuyn qua tit din thng ca mt vt dn. in lng q s c xc nh nh th no ? A: Bng tng i s in lng ca cc ion m v in lng ca cc in dng chuyn qua tit din . B: Bng tng s cc ion m v ion dng chuyn qua tit din .

C: Bng in lng ca cc ion m hoc ion dng chuyn qua tit din . D: Bng tng ln in lng ca cc ion m v in lng ca cc ion dng chuyn qua tit din .p n ng: A Cu 73 ( Cu hi ngn)

c im no sau y khng phi l chung ca tt c cc loi ngun in ? A: C mt cc dng v mt cc m. B: C hai cc lm bng than ch. C: C hai loi cc nhim in khc nhau. D: C hai cc, gia hai cc lun lun c s chnh in th.p n ng: B Cu 74 ( Cu hi ngn)

Tc dng chnh ca ngun in l: A: To ra in tch t do. B: Duy tr s chnh lch in th. C: Duy tr s tn ti ca electron t do. D: Duy tr s chuyn ng ca cc electron.p n ng: B Cu 75 ( Cu hi ngn)

Khi ngt ngun in ra khi vt dn bng kim loi th cc electron t do A: Dng ngay lp tc li. B: Chuyn ng theo qun tnh ri t t dng li. C: Vn tip tc chuyn ng nhng hn lon. D: Khng th xc nh c l electron t do c chuyn ng na hay khng.p n ng: C Cu 76 ( Cu hi ngn)

Cc in tch dch chuyn trong ngun in nh th no ? A: Ht mang in dng dch chuyn cng chiu in trng, ht mang in m dch chuyn ngc chiu in trng.

B: Ht mang in m dch chuyn v cc dng, ht mang in dng dch chuyn v cc m. C: lectron dch chuyn cng chiu in trng, i v cc dng. D: Ht mang in m dch chuyn v cc m, ht mang cc dng dch chuyn v cc dng.p n ng: D Cu 77 ( Cu hi ngn)

Cu pht biu no sau y khng chnh xc ? A: Cc in tch bn trong v bn ngoi ngun in dch chuyn thnh mt vng kn. B: Cc in tch bn trong v bn ngoi ngun in dch chuyn theo mt chiu. C: lectron t do bn trong v bn ngoi ngun in lun lun dch chuyn v pha cc dng. D: in tch dng di chuyn cng chiu in trng bn ngoi ngun in v ngc chiu bn trong ngun in.p n ng: C Cu 78 ( Cu hi ngn)

Lc l trong ngun in khng thc hin cng vo vic no sau y ? A: Dch chuyn in tch dng ngc chiu in trng. B: Thc hin cng thng cng ca in trng tnh. C: Dch chuyn in tch m cng chiu in trng. D: Cung cp in tch t do cho cc vt dn ni vi ngun in.p n ng: D Cu 79 ( Cu hi ngn)

n v no sau y khng phi n v ca sut in ng ? A: Nm 2 C kgm 2 s 2 .C

B:

C: V. D: J/C.p n ng: A Cu 80 ( Cu hi ngn)

Pht biu no sau y v sut in ng l khng chnh xc ? A: Sut in ng l i lng c trng cho kh nng thc hin cng ca ngun in. B: K hiu ca sut in ng l C: Sut in ng ca ngun in c gi tr bng hiu in th gia hai cc ca n. D: ln ca sut in ng khng ph thuc vo s ht ti in m n lm dch chuyn t cc ny sang cc kia bn trong ngun in.p n ng: C Cu 81 ( Cu hi ngn)

Thng s c trng ca ngun in l g ? A: Sut in ng. B: Sut in ng v in tr trong. C: Kh nng thc hin cng. D: Lng in tch c trong ngun.p n ng: B Cu 82 ( Cu hi ngn)

Sut in ng ca ngun in l i lng c trng cho A: Kh nng di chuyn in tch nhanh hay chm ca ngun in. B: Kh nng d tr in tch cc cc ca ngun in. C: Kh nng thc hin cng ca ngun in. D: Kh nng to ra hiu in th ln hay nh ca ngun in.p n ng: C Cu 83 ( Cu hi ngn)

Pin Von-ta v c quy ch l hai ngun in. Gia chng c im chung no ? A: C hai in cc bng ch v ch dioxit. B: C lc ha hc ng vai tr lc l. C: C th np li s dng nhiu ln. D: C sut in ng n nh khong 1,1V.

p n ng: B

Cu 84 ( Cu hi ngn)

Dung dch ttrong c quy ch l A: NaOH c. B: H2SO4 long. C: NaOH long. D: H2SO4 c.p n ng: B Cu 85 ( Cu hi ngn)

Hiu in th in ha A: L hiu in th gia hai cc ca mt ngun in. B: L hiu in th gia hai cc ca mt ngun in ha hc. C: Khng ph thuc vo nng ca dung dch in phn. D: L chnh lch in th gia dung dch in phn v thanh kim loi tip xc vi dung dch .p n ng: D Cu 86 ( Cu hi ngn)

Hiu in th in ha khng ph thuc vo A: Khi lng cht in phn. B: Bn cht thanh kim loi. C: Bn cht dung dch in phn. D: Nng dung dch in phn.p n ng: A Cu 87 ( Cu hi ngn)

t mt thanh st v mt thanh ng vo trong dung dch ng H2SO4. Hiu in th gia thanh st v thanh ng s A: Ln hn khng. B: Nh hn khng. C: Khng th xc nh c. D: Ph thuc vo nng dung dch H2SO4.

p n ng: A Cu 88 ( Cu hi ngn)

im khc nhau c bn gia pin v c quy l. A: Kch thc. B: Hnh dng. C: Nguyn tc hot ng. D: S lng cc cc.p n ng: C Cu 89 ( Cu hi ngn)

Cho mch in nh hnh ve. R1 = 15 ; R2 = R3 = R4 = 10 . UAB = 30V. Tm cng dng in qua cc in tr v s ch ampe k.

p n:

Cu to mch: R1 // [ R2 nt ( R3 / / R4 )] . I1 = 2A; I2 = 2A; I3 = I4 = 1A; IA = 1ACu 90 ( Cu hi ngn)

Cho mch in nh hnh ve. UAB = 9V ; R1 = 8 , R2 = 2 , R3 = 4 , RA = 0. Tm s ch v chiu ca dng in qua ampe k

p n:

IA = 0,75A, chiu DCCu 91 ( Cu hi ngn)

Cho mch in nh hnh ve

t vo hai u mch hiu in th U = 6V. K m A1 ch 1,2A. K ng A1 ch 1,4 A, A2 ch 0,5A Tnh R1; R2; R3 bit in tr cc ampe k bng khng.p n:

Km: 6 = (R1 + R2) .1,2; Kng: 6 = 1,4R1 + 0,9R2 => R1 = 3 ; R2 = 2 , R3 = 3,6 .Cu 92 ( Cu hi ngn)

Cho mch in nh hnh ve. UAB = 16 V; R1 = 6 ; R3 = 12 ; RA = 1 ; Rx l bin tr.

a. Rx = 18 . Tnh s ch ca ampe k. b. Rx c gi tr bao nhiu khi ampe k ch 1A. c. khi Rx gim th s ch ca ampe k tng hay gim.p n:

a. 1,6A. b) Rx = 90 Cu 93 ( Cu hi ngn)

Cho mch in nh hnh ve. U = 18V; R1 = R3 = 3 ; R2 = 4 ; R4 = 6 ; I = 3A. Hy xc nh Rx va chi s ca ampe k.

p n:

R1 nt Rx / / R2 nt ( R3 / / R4 ) .Rx = 6 v IA = 2,5A

{

}

Cu 94 ( Cu hi ngn)

Cho mch in nh hnh ve. R1 = 15 ; R2 = R3 = R4 = 10 ; IAB = 3A. Tm cng dng in qua cc in tr v s ch ca ampe k.

p n:

R1 // R2 nt ( R3 / / R4 ) => I1 = 2A; I2 = 2A; I3 = I4 = 1A; IA = 1A Cu 95 ( Cu hi ngn)


UAB = 12V; R1 = 3 , R2 = 4 ; R3 = 5 . Hy xc nh s ch ca vn k.p n:

V1 ch 7V; V2 ch 4V; V3 ch 5V

Cu 96 ( Cu hi ngn)


R1 = R2 = 10 , R4 = 3 ; UAB = 18V. a. Ni M v B bng mt vn k c in tr v cng ln. S ch ca vn k l 10V. Tnh R3. b. Ni M v B bng mt ampe k c in tr RA = 0 . Xc nh s ch ca ampe k.p n:

a. I1 = 0,8A; I2 = 1,2A=> R = 5 . b. IA = 2,37ACu 97 ( Cu hi ngn)


= 30V; r = 3 ; R1 = 12 ; R2 = 36 ; R3 = 18 ;

RA = 0. Tm s ch ampe k v chiu dng in qua n.p n:

R23 = 12 => I1 = I23 = 10/9 => IA = 20/27A; chiu t M-N.Cu 98 ( Cu hi ngn)


= 7,8V; r = 0,4 ; R1 = R2 = R3 = 3 ;R4 = 6 . Tm UMN. Ni M v N bng dy dn.Tm IMN.p n:

UMN = -1,17V; IA = 1/3ACu 99 ( Cu hi ngn)


= 12V; r = 0,1 ; R1 = R2 = 2 ; R3 = 4 ; R4 = 4,4 .Tm I qua cc in tr.p n:

I1 = 1,5A; I2 = 0,5A; I = 2ACu 100 ( Cu hi ngn)

Cho mch in nh hnh ve.

= 30V; r = 2,4 ; R1 = 4 ; R2 = 6 ; R3 = 2 ;R4 = 3 ; R5 = 1 .Tnh cng dng in qua mi in tr.p n:

Cu cn bng. I4 =2A; I1 = 1,5A; I2 =I3 = 0,5A.Cu 101 ( Cu hi ngn)


R1 = R2 = 6 ; R3 = 3 ; r =5 ; RA = 0. ampe k 1chi 0,6A. Tm v s ch ca ampe k 2.p n:

R1 // R2 // R3 => IA2 = 0,4A; = 5,2VCu 102 ( Cu hi ngn)

Hai ngun in mc ni tip vi nhau v vi mt in tr th cho dng in 4A qua in tr. Nu o cc ca mt ngun th dng in ch cn 1A. Sut in ng ca mt ngun l 12V. in tr trong ca c hai ngun khng ng k. Tm sut in ng ca ngun th hai.p n:

1 + 2 = 4R v 1 2 =R => 1 = 20VCu 103 ( Cu hi ngn)

Cho mch in nh hnh ve. : 20V-2 ; R = 1 ; R3 = 1 . Khi k m v k ng I2 lun l 1A. Tnh R2 v R4.

p n:

Km: (R1nt R3) // (R2nt R4); Kng: (R1//R2) nt (R3 // R4) => R2 =9 Cu 104 ( Cu hi ngn)


1: 6V - 1 ; r2 = 3 ; R1 = R2 = R3 = 6 .p n:

Vn k ch 3V. Tnh 2.

Hoc sinh t giaiCu 105 ( Cu hi ngn)

Mt ng c in c r = 2 , khi hot ng bnh thng cn hiu in th U = 9V v I = 7,5A. a. Tnh cng sut v hiu sut phn in ca ng c in. b. ng c b kt khng quay c. Tnh cng sut ca ng c nu hiu in th t vo n khng i.p n:

P = 6,75W; H = 0,833, = 7,5V. b. P = 40,5WCu 106 ( Cu hi ngn)


= 12V ; r = 2 ; R1 = 4 ; R2 = 2 .a. Tm R3 cng sut mch ngoi cc i. b. Tm R3 cng sut tiu th ca R3 bng 4,5W.p n:

R3 = 2; R3 = 50/9Cu 107 ( Cu hi ngn)


1 = 24V, 2 = 6V; r = r2 =2 ; : 12 6W. n sng bnh thng.a. Tnh cng dng in qua 1. b. Tnh R.p n:

a. 1,5A; b. R = 24VCu 108 ( Cu hi ngn)

Cho mch in nh hnh ve .1 : 6V 3W; 2 : 12V 12W, c hai u hot ng bnh thng. Ngun : 24V - 4 . Hy xc nh R3 v R4.

p n:

R3 = 6 ; R4 = 12

Cu 109 ( Cu hi ngn)

Mt ngun in c sut in ng 2V v in tr trong 1 . Xc nh cng dng in khi mch ngoi tiu th cng sut 0,75W.p n:

1,5A v 0,5A.Cu 110 ( Cu hi ngn)

Mt mch in kn gm mt ngun in v mt bin tr. Khi R = R 1 = 4 th cng sut nhit bng vi khi R = R2 = 9 . Tnh in tr trong ca ngun in.p n:

6Cu 111 ( Cu hi ngn)

Bp in c cng sut 600W, hiu in th 120V. Dng bp ny un si 2 lt nc t 200 C. Hiu sut bp l 80%. Nhit dung ring v khi lng ring ca nc l 4200J/kg v 1000 kg/m 3. Tm in nng tiu th v thi gian un nc.p n:

Q = mc. t 0 = 672kJ => A = 840kJ => t = 1400sCu 112 ( Cu hi ngn)

Cc ngun ging nhau, mi ngun 0 = 1,5V ; r0 = 1,5 mc thnh b i xng thp sng bnh thng n 12V 18W. a. Tm cch mc ngun. b. Cch mc no c s ngun t nht. Tnh cng sut v hiu sut mi ngun lc .p n:

( 64 ngun thnh 2 hng hoc 48 ngun 3 hng; 0,75W 50%)

Cu 113 ( Cu hi ngn)


1

= 18V; r1 = r2 = 1 . 1: 6V 12W; 2 : 12V 6W.

Hai n sng bnh thng. a. Tnh cng dng in nh mc v in tr mi bng n. b. Tnh R. c. Tnh 2 .p n:

a. I1 = 2A; R1 =3 ; I2 = 0,5A; R2 = 24 b. R = 8 ; c. 2 = 4VCu 114 ( Cu hi ngn)

Hai ngun c sut i ng nh nhau

1

=

2

=

; cc in tr trong r1 v r2 khc nhau. Bit

cng sut ln nht m mi ngun c th cung cp c cho mch ngoi l 15W v P2 = 20W. Tnh cng sut ln nht m c hai ngun c th cung cp cho mch ngoi khi chng mc ni tip v khi chng mc song song.p n:

Pnt = 34,3W; P// = 35WCu 115 ( Cu hi ngn)

Ngun = 15V; r = 1 ni vi mch ngoi gm R1 = 2 v R2 mc song song. Tnh R2 cng sut tiu th trn R2 cc i.p n:

R2 = 2/3 Cu 116 ( Cu hi ngn)

Hai ngun sut in ng

1

= 1,9V;

2

= 1,1V; in tr trong r1 = 0,1 ; r2 = 0,8 c mc

song song vi nhau thnh b. B ngun ny c mc vi in tr R = 10 . Tm cng sut ta nhit trn mi ngun v cng sut ngun pht ra.p n:

0,11W; 0,06W v 2W; -0,96WCu 117 ( Cu hi ngn)


= 16V; r = 4 ; R = 12 . Cng sut tiu th trn R l 9W.

Tnh cng sut v hiu sut ca ngun.p n:

I = 0,866A => P = 13,86W; H = 78,4%Cu 118 ( Cu hi ngn)


1

= 20V; r1 = 1 ; 2 = 32V; r2 = 0,5 ;

R = 2 . Tm cng dng in qua mi nhnh.p n:

I1 = 4A; I2 = 16A; I3 = 12ACu 119 ( Cu hi ngn)


= 170V; r = 5 ; R1 = 195 ;

R2 = R3 = 200 . Vn k ch 100V. Tm in tr vn k.p n:

RV = 1000

Cu 120 ( Cu hi ngn)


1

= 24V; r = 1 . 2 = 4V; r2 = 2 ; R1 =1 ; R2 = 1 ; R3 = 4 .

Xc nh cng dng in qua 1 ,p n:

2

; R3 khi K ng v khi K m.

Km: I = 4A; K ng: I1 = 5,85A; I2 = 2,77A, my thu; I3 = 3,08ACu 121 ( Cu hi ngn)


1

= 15V; r1 = 1 ; 2 = 3 = 7,5V; r2 = r3 =1 ; R1 =16 ; R2 = 8 .

a. Tnh UAB. b. Tnh cng dng in i qua

,1

2

, R1.

c. Tnh UMN.p n:

a. UAB = 14,6V. b. I1 = 0,4A; I2 = 0,2A; IRl = 0,6A. c. UMN =2,3V.Cu 122 ( Cu hi ngn)


R2 = R3 = R4 = 2 ; R1 = 1,5 ; bao nhiu v mc nh th no khng c dng in i qua R2.p n:

= 1,5V v r = 0,5 . Phi mc AB vo mt hiu in th l

UAB = 3VCu 123 ( Cu hi ngn)


1

= 6V; r1 = 2 ; r2 = 0,5 ; R = 2 ; RA = 0.

Ampe k ch 2A. Tm 2 .p n:

E2 = 4,5VCu 124 ( Cu hi ngn)

Cho mch in c cu to nh hnh ve.

bit 1 = 25 V; r1 = 2 ; 2 = 12V; r2 = 1 ;

R1 = 3 ; R2 = 6 ; R3 = 3 ; R4 = 7,5 . a.Tnh cng dng in qua cc in tr, ngun, ampe k. b. Thay ampe k bng mt t c in dung C = 6 F. Hy tnh in tch ca t in.p n:

a. IE1 = I1 = 2,3A; IE2 = 0,5A, may thu; I2 = 0,16A, I3 = 0,33A; I4 = 1,8A. IA = 2,14A. b) UC = U2 + U3 = 10,53V.=> q = 63,18 C.Cu 125 ( Cu hi ngn)

Mt acquy c sut in ng 12V. Dng in np c cng 1A khi hiu in th hai cc ca acquy l 15V. Tm in tr trong ca acquy.p n:

r = 3Cu 126 ( Cu hi ngn)

Nu trong thi gian t = 0,1s u c in lng q = 0,5C v trong thi gian t = 0,1s tip theo c q = 0,1C chuyn qua tit din ca vt dn th cng dng in trong c hai khon thi gian l A: I = 6A B: I = 3A C: I = 4A D: I = 2A.p n ng: B Cu 127 ( Cu hi ngn)

Vi dng in khng i c cng I, nhn xt no sau y l sai ? A: Nu lng in tch qua tit din dy dn tng bao nhiu ln th I tng by nhiu ln. B: th biu din I theo t l mt ng thng xin gc vi trc Ot. C: tnh I c th ly q ng vi thi gian t ty . D: Nu I = 5A th c trong 2s bt k c 10C chuyn qua tit din thng ca dy dn.

p n ng: B Cu 128 ( Cu hi ngn)

T cng thc ca nh lut m vi on mch l I = U/R suy ra nhiu kt lun di y. Hy chn cu ng. A: gim th trn on mch U = IR t l thun vi I. B: in tr cu on mch t l thun vi hiu in th C: in tr ca on mch t l nghch vi cng dng in. D: C th dng cng thc R = U/I xc nh R.p n ng: D Cu 129 ( Cu hi ngn)

ng c trng vn ampe ca mt vt dn l A: ng biu din s ph thuc ca hiu in th U t vo v cng I qua vt dn. B: ng biu din s ph thuc ca cng I v hiu in th U t vo vt dn. C: ng biu din s ph thuc ca hiu in th U t vo v in tr R ca vt dn. D: ng biu din s ph thuc ca cng I qua vt dn v in tr R ca vt dn.p n ng: B Cu 130 ( Cu hi ngn)

ng c trng vn ampe ca vt dn tun theo nh lut m cho on mch l A: ng thng nm ngang. B: ng thng hng ln v ct trc tung ti mt im khc khng. C: ng thng hng xung. D: ng thng hng ln v qua gc ta .p n ng: D Cu 131 ( Cu hi ngn)

Mt dy dn ng cht hnh tr c in tr R. Nu ct dy thnh 3 on bng nhau th in tr ca mi on s l A: R = 3R B: R = 9R C: R = R/3.

D: R = R/9.p n ng: C Cu 132 ( Cu hi ngn)

Mc ngun in vi mt mch ngoi, cc ht electron mch ngoi A: chuyn ng t cc dng n cc m. B: chuyn ng cng chiu in tng. C: chuyn ng di tc dng ca lc l. D: chuyn ng di tc dng ca lc in trng.p n ng: D Cu 133 ( Cu hi ngn)

Trong ngun in lun c mt lc l l: A: lc in trng. B: lc t C: lc ha hc. D: lc khc lc in trng.p n ng: D Cu 134 ( Cu hi ngn)

Sut in ng ca ngun in l i lng c trng cho kh nng sinh cng ca ngun. Cng l ca A: lc in trng. B: lc l. C: lc in trng v lc l. D: lc tng tc gia cc ht mang in.p n ng: B Cu 135 ( Cu hi ngn)

Hai ngun in c ghi s vn l 10V v 20 V. Nhn xt no sau y ng? A: Hai ngun ny lun to ra mt hiu in th 10V, 20V cho mch ngoi. B: Kh nng sinh cng ca hai ngun l 10J v 20J. C: Kh nng sinh cng ca ngun th nht bng na ngun th hai.

D: Ngun th nht lun sinh cng bng na ngun th hai.p n ng: C Cu 136 ( Cu hi ngn)

nh ngha no v dng in l nh ngha chnh xc nht. A: Dng in l dng chuyn di c hng ca cc in tch dng. B: Dng in l dng chuyn di c hng ca cc in tch m. C: Dng in l dng chuyn di c hng ca cc ht mang in. D: Dng in l dng chuyn di c hng ca cc electron.p n ng: C Cu 137 ( Cu hi ngn)

Khi c dng in th A: Cc in tch dng dch chuyn t tri sang phi. B: Cc in tch dng dch chuyn t trn xung di. C: Cc in tch dng dch chuyn t ni c in th thp n ni c in th cao. D: Hiu in th gia hai im m cc in tch dng di chuyn qua ln hn khng.p n ng: D Cu 138 ( Cu hi ngn)

Khi c dng in trong dy dn bng kim loi th A: ch c cc proton mi dch chuyn. B: ch c cc ht nhn mi dch chuyn. C: ch cc electron t do mi dch chuyn. D: ch c cc electron lp v ngoi mi dch chuyn.p n ng: C Cu 139 ( Cu hi ngn)

Ht no sau y khng th l ht ti in. A: proton. B: notron. C: electron. D: ion.


Dng in khng c tc dng no trong s cc tc dng sau y? A: Tc dng c B: Tc dng nhit. C: Tc dng t. D: Tc dng ha hc.p n ng: A Cu 141 ( Cu hi ngn)

Tc dng no l tc dng c trng ca dng in. A: Tc dng ha hc. B: Tc dng t.

C: Tc dng nhit. D: Tc dng nhit v tc dng ha hc.p n ng: B Cu 142 ( Cu hi ngn)

Nc c th tch ra thnh oxi v hyro khi c dng in i qua. l nh tc dng g ca dng in? A: Tc dng ha hc. B: Tc dng t. C: Tc dng nhit. D: Tc dng nhit v tc dng ha hc.p n ng: A Cu 143 ( Cu hi ngn)

Tc dng no ca dng in lun lun c, khi n i qua mi loi mi trng? A: Tc dng ha hc. B: Tc dng nhit. C: Tc dng t.

D: Tc dng quang hc.p n ng: C Cu 144 ( Cu hi ngn)

Cng dng in c xc nh bi. A: s lng electron chuyn qua tit din thng ca vt dn trong mt n v thi gian. B: lng in tch chuyn qua tit din thng ca vt dn trong mt n v thi gian. C: lng ion dng chuyn qua tit din thng ca vt dn trong mt giy. D: s ht ti in chuyn qua tit din thng ca vt dn trong mt giy.p n ng: B Cu 145 ( Cu hi ngn)

Mt on vt dn c dng hnh hp ABCDABCD, hnh ve.

Nu dng in i vo vo v i ra vung gc vi mt bn AADD v BBCC th in tr ca n c tnh theo cng thc no sau y? A: R = B: R = C: R = AB AA '. A ' B ' AA ' AD.DD ' AB AA '. A ' D '

D: R =

AC . AD.DC

p n ng: C Cu 146 ( Cu hi ngn)


Ampe k ch 2A. Hi s ch ca vn k l bao nhiu? A: 2 B: 4 C: 6 D: 8 .p n ng: D Cu 147 ( Cu hi ngn)

Trong s mch in hnh ve di, vn k ch 6V.

Hi gi tr ca in tr R l bao nhiu? A: 1 . B: 12

C: 6 D: 3 .p n ng: C Cu 148 ( Cu hi ngn)

Dng in khng i l: A: dng in c cng khng i theo thi gian. B: dng in mt chiu c cng khng i theo thi gian. C: dng cc in tch chuyn ng u. D: dng in c chiu khng i theo thi gian.p n ng: B Cu 149 ( Cu hi ngn)

gim in th gia hai im bt k trn mt on dy dn A: Khng ph thuc vo in tr ca on dy dn . B: Khng ph thuc vo cng dng in i qua on dy dn . C: L mt gi tr khng i nu cng dng in i qua on dy l dng in khng i. D: C ln tun theo biu thc ca nh lut m.p n ng: D Cu 150 ( Cu hi ngn)

n v no sau y khng phi l n v o cng dng in. A: C/s. B: N.m/V.s. C: N.V/m.s D: mA.p n ng: C Cu 151 ( Cu hi ngn)

Cng thc no sau y khng phi l cng thc xc nh cng dng in ca dng in khng i. Vi n l s lng lectron hoc s lng ht mang in chuyn qua tit din thng ca dy dn trong thi gian t .

A: I =

q . t q t n. e t n. q t

B: I =

C: I =

D: I =

p n ng: D Cu 152 ( Cu hi ngn)

Khi s dng c quy cn ch n nhng iu g ? I Sut in ng III Dung lng A: I,II,III. B: III, IV, I. C: II, III, IV. D: IV, I, II.p n ng: A Cu 153 ( Cu hi ngn)

II Th tch dung dch. IV Th tch c quy.

Nng lng c quy chuyn ha theo qu trnh no di y. A: Ha nng => in nng. B: in nng => ha nng => in nng. C: Ha nng => in nng => ha nng. D: in nng => ha nng => c nng.p n ng: B Cu 154 ( Cu hi ngn)

Sau khi dng mt thi gian pin yu i l do nguyn nhn g ? A: Hiu in th in ha gim i. B: Khi lng ca cc dng gim i C: in tr trong ca pin tng ln.

D: Dung dch in phn trong pin b mt i do bay hi.p n ng: C Cu 155 ( Cu hi ngn)

Cu to ca pin in ha l. A: Gm hai cc c bn cht ging nhau ngm trong dung dch in phn B: Gm hai cc c bn cht khc nhau ngm trong dung dch in phn. C: Gm hai cc c bn cht khc nhau ngm trong in mi. D: Gm hai cc c bn cht ging nhau ngm trong in mi.p n ng: B Cu 156 ( Cu hi ngn)

Trong trng hp no sau y ta c mt pin in ha. A: Mt cc nhm v mt cc ng cng nhng vo nc mui. B: Mt cc nhm v mt cc ng cng nhng vo nc ct. C: Hai cc cng bng ng ging nhau nhng vo nc vi. D: Hai cc nga khc nhau cng nhng vo du ha.p n ng: A Cu 157 ( Cu hi ngn)

Nhn xt no sau y v c quy ch l khng ng ? A: Acquy ch c mt cc lm bng ch v mt cc lm bng ch dioxit. B: Hai cc ca acquy chi c ngm trong dung dch H2SO4 long. C: Khi np in cho acquy, dng in i vo t cc m v i ra t cc dng. D: Acquy l ngun in c th np li s dng nhiu ln.p n ng: C Cu 158 ( Cu hi ngn)

Khi acquy pht in th qu trnh no sau y khng xy ra ? A: Bn cht ha hc ca cc bn cc thay i. B: Sut in ng trn acquy gim. C: Dung dch axit b in phn. D: Dung lng acquy gim.


in nng tiu th ca mt on mch in l. A: Cng ca lc in lm dch chuyn in tch t do trong on mch. B: Cng ca dng in chy qua on mch. C: Tch ca hiu in th, cng dng in v thi gian ca dng in chy qua on mch. D: Tt c cc trng hp trn.p n ng: D Cu 160 ( Cu hi ngn)

Dng c tiu th in l dng c A: Chuyn ha in nng thnh nhit nng. B: Chuyn ha in nng thnh cc dng nng lng khc. C: Chuyn ha in nng thnh c nng. D: Chuyn ha in nng thnh quang nng.p n ng: B Cu 161 ( Cu hi ngn)

Cng sut tiu th ca mt on mch in l 100W , iu ny c ngha A: Dng in chy qua on mch sinh c mt cng l 100W B: Dng in chy qua on mch sinh c mt cng l 100W trong mt giy. C: Ngun in sinh ra mt cng l 100J. D: Ngun in sinh ra mt cng l 100J trong mt giy.p n ng: B Cu 162 ( Cu hi ngn)

Hai vt dn c in tr R1 v R2 . Dng in qua chng l I1 = 2I2 trong cng mt thi gian nhit lng ta ra trn hai vt bng nhau. Chn kt lun ng. A: R1 = 2R2. B: R1 = 4R2. C: R1 = R2/2.

8D. R1 = R/4.p n ng: A Cu 163 ( Cu hi ngn)

Dng c no c tnh cng sut tiu th theo cng thc p = U2/R ? A: Qut in. B: Bnh acquy ang np in. C: Bp in. D: T lnh.p n ng: C Cu 164 ( Cu hi ngn)

Trong on mch ch c in tr thun th A: Cng ca dng in bng ni nng ca vt dn. B: Cng ca dng in bng nhit lng ta ra trn vt dn. C: Cng ca dng in khng ph thuc thi gian dng in chy qua. D: Cng ca dng in khng ph thuc in tr vt dn.p n ng: B Cu 165 ( Cu hi ngn)

Trong on mch ch c hai in tr R, nu gim hiu in th hai u on mch i 3 ln th nhit lng ta ra trong cng thi gian s A: gim i 3 ln B: gim i 9 ln. C: tng ln 3 ln. D: tng ln 9 ln.p n ng: D Cu 166 ( Cu hi ngn)

Trong on mch ch c in tr R, nu tng hiu in th hai u on mch ln 2 ln m mun nhit lng ta ra vn nh c th thi gian dng in chy qua mch phi thay i nh th no. A: gim i 2 ln B: gim i 4 ln.

C: tng ln 2 ln. D: tng ln 4 ln.p n ng: B Cu 167 ( Cu hi ngn)

Trn mt dng c in c ghi 6V 12W. dng c hot ng bnh thng th dng in qua n phi c A: I = 6A. B: I = 0,5A. C: I = 2A. D: I = 12A.p n ng: C Cu 168 ( Cu hi ngn)

Chn cu pht biu sai v cng sut ca dng in. A: Cng sut ca dng in c gi tr bng cng ca ngun in thc hin trong mt giy. B: Cng sut ca ngun in l cng sut ca lc l trong ngun. C: Cng sut ca ngun in bng cng sut tiu th ca mch ngoi. D: Cng sut ca dng in c o bng tch s gia sut in ng v cng dng in.p n ng: C Cu 169 ( Cu hi ngn)

Th no l mt my thu in? A: L mt dng c tiu th in nng. B: L mt dng c bin i in nng thnh in nng. C: L mt dng c bin i in nng. D: L mt dng c bin i mt phn in nng thnh nhit nng.p n ng: D Cu 170 ( Cu hi ngn)

Chn cu pht biu ng v sut phn in ca my thu. A: l i lng o bng t s gia cng ca dng in qua my thu vi in lng chuyn qua my.

B: l i lng c trng cho may thu v s chuyn ha in nng thnh nhit nng. C: l i lng c trng cho may thu v s chuyn ha in nng thnh cc dng nng lng khc ngoi nhit. D: l i lng c trng cho may thu v hiu qu ca s chuyn ha nng lng.p n ng: C Cu 171 ( Cu hi ngn)

in nng tiu thu ca mt my thu in A: l phn in nng chuyn ha thnh nhit. B: l phn in nng chuyn ha thnh nng lng khc nhit. C: l cng ton phn dng in thc hin my thu. D: l phn in nng tiu th xc nh theo cng thc: .I.t + rp.I.t.p n ng: C Cu 172 ( Cu hi ngn)

Pht biu no sau y l sai ? Sut phn in ca my thu. A: c ln t l vi in nng m my thu chuyn ha thnh dng nng lng khc, khng phi l nhit. B: l i lng c trng cho my thu v phng din chuyn ha nng lng. C: c ln thay i ty theo hiu in th t vo my thu. D: c k hiu l p.p n ng: C Cu 173 ( Cu hi ngn)

Hiu in th t vo my thu my thu hot ng c phi A: c ln bng vi sut phn in ca my thu. B: c ln c tnh theo biu thc U = p + I.r.p. C: rt ln. D: c ln c tnh theo biu thc. U = p + r.p.I2.p n ng: B Cu 174 ( Cu hi ngn)

Cc in tch dch chuyn trong my thu nh th no ? A: Ht mang in dng dch chuyn ngc chiu in trng, ht mang in m dch chuyn cng chiu in trng. B: Ht mang in m dch chuyn v cc dng, ht mang in dng dch chuyn v cc m. C: Electron dch chuyn ngc chiu in trng, i v cc m. D: Ht mang in m dch chuyn v cc m, ht mang in dng dch chuyn v cc dng.p n ng: B Cu 175 ( Cu hi ngn)

Trong cc biu thc xc nh hiu sut ca my thu in sau y, biu thc no sai ? A: H = 1 -

rp

p

.I

U

. .I

B: H =

+rU

p

C: H =

U

p

D: H =

U + r p.I U

.


Hiu sut ca my thu in l i lng c trng cho A: mc hao ph ca my thu . B: kh nng sinh cng ca my thu. C: mc tiu th in cu my thu. D: kh nng chuyn ha in nng thnh cc dng nng lng khc.p n ng: A Cu 177 ( Cu hi ngn)

Si dy ta nhit trong chic bn l cn c c tnh g trong cc c tnh sau ? A: C in tr ln v nhit nng chy ln. B: C in tr nh v nhit nng chy ln.

C: C in tr ln v nhit nng chy nh. D: C in tr nh v nhit nng chy nh.p n ng: A Cu 178 ( Cu hi ngn)

Trong s mch in ngi ta cn c vo iu g phn bit my thu v ngun in ? A: Ngun in l thit b sinh cng cn my thu l thit b nhn cng. B: Dng in i ra t cc dng ca ngun in v i vo cc dng ca my thu. C: Ngun in bin nng lng khc thnh nng lng in cn my thu th ngc li. D: lectron di chuyn cng chiu in trng bn trong ngun in v ngc chiu in trng bn trong my thu.p n ng: B Cu 179 ( Cu hi ngn)

Trong mt on mch c hiu in th khng i nu cng dng in qua in tr tng ln ba ln th nhit lng trn in tr thay i nh th no ? A: Tng 3 ln. B: Gim ba ln. C: Khng thay i. D: Tng 9 ln.p n ng: A Cu 180 ( Cu hi ngn)

Mt on mch c hiu in th hai u khng thay i. Khi in tr ca mch l 100 th cng sut tiu th ca mch l 100 W. Khi in tr ca mch l 50 th cng sut tiu th ca mch l bao nhiu ? A: 10W. B: 5W. C: 40W. D: 80W.p n ng: C Cu 181 ( Cu hi ngn)

Vi ngun in 24V th c th mc ti a bao nhiu bng n loi 6V, m bng n vn sng bnh thng. A: 4 bng. B: 5 bng. C: 6 bng. D: Khng xc nh c.p n ng: D Cu 182 ( Cu hi ngn)

th no trong hnh ve th hin khng ng mi quan h gia nhit lng ta ra trn mt on mch vi cc i lng khc trong biu thc ca nh lut Jun- lenx?

p n:

A ungCu 183 ( Cu hi ngn)

th no trong hnh ve th hin khng ng mi quan h gia cng ca dng in sinh ra trn mt on mch vi tng i lng, khi cc i lng khc khng i?

p n:


Cch mc vn k v ampe k trong s no hnh ve di l ng ?

p n:


Biu thc no khng tng ng vi s on mch hnh ve ?

A: I =

R1 + R2 + r R+r

B: I =

C: UAB = - I.r. D: = I.(R1 + R2 + r).p n ng: B

Cu 186 ( Cu hi ngn)

Dy ch trong cu ch b hng. Nu thay th bng loi dy khc, th dy phi tha mn c yu cu g? A: in tr ln v nhit nng chy thp. B: in tr ln v nhit nng chy ln. C: in tr nh v nhit nng chy thp. D: in tr nh v nhit nng chy ln.p n ng: A Cu 187 ( Cu hi ngn)

Trong hin tng on mch A: in tr mch ngoi rt ln. B: cng dng in chy trong mch c xc nh bi biu thc.

I = R+r .

C: hai cc ca ngun c ni tt vi nhau bi mt dy dn. D: cng dng in trong mch rt nh.p n ng: C Cu 188 ( Cu hi ngn)

Mt hc sinh tin hnh th nghim xc nh mi quan h I R.

Do s nn b mt mt s liu. Hy chn mt trong cc gi tr di y in vo c du ? trong bng. Bng s liu:

A: 4 . B: 3 C: 1,5 D: 3,5 .p n ng: B Cu 189 ( Cu hi ngn)

Hiu sut ca ngun in c xc inh bi biu thc no trong s cc biu thc sau y ? A: H =

AcchA

B: H =

. U

C: H =

AcchA

=

Up

D: H =

I .r


Da vo hiu sut ca ngun in ngi ta c th bit c. A: mc cung cp nng lng cho mch ngoi ca ngun. B: sut in ng ca ngun. C: phn trm nng lng m ngun tiu th. D: mi c ca ngun.p n ng: C Cu 191 ( Cu hi ngn)

Khi khi ng xe my, khng nn nhn nt khi ng () qu lu v nhiu ln lin tc v A: dng on mch ko di ta nhit mnh s lm hng acquy.

B: tiu hao qu nhiu nng lng. C: ng c s rt nhanh hng, D: hng nt khi ng.p n ng: A Cu 192 ( Cu hi ngn)

Trong s mch in hnh ve

Vn k ch 3V; ampe k ch 0,5A. Hi gi tr ca in tr R l bao nhiu? A: 0,5 . B: 1,5 . C: 5 . D: 6 .p n ng: C Cu 193 ( Cu hi ngn)

Biu thc no sau y l biu thc nh lut m i vi on mch cha my thu? A: I =

U U R U

AB

P

P

rAB AB

B: I =

P

+rP .

C: I =

AB

r

D:

U

AB

+P

P

r

p n ng: A Cu 194 ( Cu hi ngn)

Biu thc no sau y l biu thc nh lut m i vi on mch cha my thu ch ta nhit? A: I =

U U R UAB

AB

p

p

rAB

B: I =

p

+rp ABAB

C: I =

R +p

.

D:

U

p

r


Biu thc I =

+U r +r +R1 2 1 2

AB

tng ng ng vi s mch in no sau y.

p n:

C ungCu 196 ( Cu hi ngn)

Cho s mach in

th no trong hnh ve di biu din ng mi quan h gia cng dng in trong mch v in tr R.

p n:

C ungCu 197 ( Cu hi ngn)

=

p

S mch in no trong hnh di tng ng vi cng thc: I = R +r +

r

p

.

p n:

B ung

Cu 198 ( Cu hi ngn)

Nhn xt no sau y l khng ng khi ni v cc ngun in ni tip nhau? A: cch mc ny khng c li do c sut in ng v in tr ca b tng ln. B: sut in ng ca b s tng ln. C: in tr ca b ln hn in tr thnh phn. D: cch mc ny gip ta c c b ngun c sut in ng ln.p n ng: A Cu 199 ( Cu hi ngn)

Vi iu kin g th hai ngun 1 v 2 trong hnh ve c coi l hai ngun mc song song?

A: Sut in ng hai ngun ging nhau. B: Hai ngun ging ht nhau. C: in tr hai ngun bng nhau. D: Hnh dng hai ngun ging nhau.p n ng: B Cu 200 ( Cu hi ngn)

Mc N ngun hn hp i xng thnh n hng, mi hng c m ngun mc ni tip. Cng thc no sau y l khng ph hp. A: b = m . B: rb =

m .rN

2

C: rb =

Nr

n

2

D: rb =p n ng: D

mr . N

Cu 201 ( Cu hi ngn)

mc c b ngun t a ngun ging nhau v in tr ca b ngun bng in t ca 1 ngun th s a phi l A: mt s nguyn. B: mt s chn. C: mt s l D: mt s chnh phngp n ng: D Cu 202 ( Cu hi ngn)

Khi s ch ca ampe k bng khng th ng thc no sau y khng ng?

A: R1.R2 = R3.R4. * B: R1.R3 = R2.R4 C: I1.R1 = I3.R3 D: I1 = I2.p n ng: A Cu 203 ( Cu hi ngn)

C th mc ni tip vn k vi pin to thnh mch kn m khng mc ni tip miliampe k vi pin to thnh mch kn v A: miliampe k c in tr rt nh, v vy gy ra dng on mch. B: in tr ca miliampe k rt nh nn gy ra sai s ln. C: gi tr cn o vt qu thang o ca miliampe k. D: kim ca miliampe k s quay lin tc v s khng c c gi tr cn o.p n ng: A Cu 204 ( Cu hi ngn)

nh lut m i vi ton mch biu th mi lin h gia. A: cng dng in v hiu in th hai u mch ngoi. B: sut in ng ca ngun vi hiu in th mch ngoi. C: cng dng in vi in tr mch ngoi. D: gia cng dng in vi sut in ng ca ngun.p n ng: D Cu 205 ( Cu hi ngn)

Mt mch in kn c mt ngun in v mt in tr R. Khi dng in chy trong mch th hiu in th gia hai cc ca ngun li nh hn sut in ng ca n. l do A: c s ta nhit trn in tr R. B: c s gim th mch ngoi. C: c s gim th mch trong. D: c s hao ph in nng.p n ng: C Cu 206 ( Cu hi ngn)

Trong trng hp no ngun in cung cp cho mch ngoi mt hiu in th ng bng sut in ng ca n ? A: in tr mch ngoi R = 0 B: in tr mch trong r = 0 C: Mch h. D: in tr mch ngoi v mch trong bng nhau (R = r)


Mt mch in kin co mt ngun in v mt in tr R. Hiu in th mch ngoi s A: tng khi cng dng in tng. B: tng khi in tr trong r tng. C: tng khi in tr ngoi R tng D: tng khi in tr ngoi R gim.p n ng: C Cu 208 ( Cu hi ngn)

Mt mch in kn c mt ngun in (in tr trong r) v mt in tr R. Cng dng in trong mch s cc i khi A: R = r/2. B: R = r. C: R = 2r. D: mt gi tr khc.p n ng: B Cu 209 ( Cu hi ngn)

Trong mch in kn c ngun, my thu, in tr R th ta c cng thc. A: = I(R + r) + B: = I(R + r) - p

p

C: = I(R + r + rp) + D: = I(R + r + rp) - p n ng: C Cu 210 ( Cu hi ngn)

p

p

Hiu sut ca ngun in cho bit A: Ngun ny c cng ca lc l ln hay nh so vi cng ca lc in. B: Ngun ny sinh cng nhanh hay chm.

C: Ngun ny sinh cng c ch ln hay nh so vi cng ton phn. D: Ngun ny sinh cng c ch ln hay nh so vi cng v ch.p n ng: C Cu 211 ( Cu hi ngn)

Cng sut c ch ca mt ngun in l A: Cng sut ca lc in trng. B: Cng sut sinh ra mch ngoi C: Cng sut sinh ra mch trong. D: Cng sut sinh ra mch trong v ngoi.p n ng: B Cu 212 ( Cu hi ngn)

Mun lm tng hiu sut ca mt ngun in, ngi ta phi A: Lm tng hiu in th mch ngoi. B: Lm gim sut in ng ca ngun. C: Lm gim in tr ca ngun. D: Lm tng in tr mch ngoi.p n ng: C Cu 213 ( Cu hi ngn)

Mt ng c in nh c in tr trong 5 , cc gi tr nh mc 10V 5W. Khi hot ng bnh thng hiu sut ca ng c l A: H = 75%. B: H = 50% C: H = 25%. D: H = 80%.p n ng: A Cu 214 ( Cu hi ngn)

Mun lm tng hiu sut ca mt my thu in, ngi ta phi A: Lm tng hiu in th my thu. B: Lm gim cng dng in my thu.

C: Lm gim in tr my thu. D: Lm tng in tr my thu.p n ng: C Cu 215 ( Cu hi ngn)

Hai bng n c cng hiu in th nh mc nhng c cng sut P 1 > P2. in tr ca bng n no ln hn ? A: R1 > R-2 B: R1 > R-2 nu dng ng hiu in th nh mc. C: R1 < R-2 . D: R1 < R-2 nu dng ng hiu in th nh mc.p n ng: D Cu 216 ( Cu hi ngn)

Mt acquy c in tr trong 5 , sut phn in l 10V ang np in vi cng sut tiu th 40W. Dng in np c cng l A: 2A. B: 8 A. C: 1,25 A. D: 20 A.p n ng: A Cu 217 ( Cu hi ngn)

Trong mt on mch cha pin (ngun) hoc acquy (my thu) c cng thc tng qut I=

U + r +RAB

. Trong l.

A: ln sut in ng ca pin. B: ln sut phn in ca acquy. C: D:

> 0 khi dng in chy vo cc dng ca pin hoc acquy. > 0 khi dng in chy vo cc m ca pin hoc acquy.

p n ng: D

Cu 218 ( Cu hi ngn)

Khi no mt ngun in tr thnh mt my thu ? A: Khi n c mc ni tip vi mt ngun khc c sut in ng ln hn. B: Khi n c mc ni tip vi mt ngun khc c sut in ng nh hn. C: Khi n c mc xung vi mt ngun khc c sut in ng nh hn. D: Khi n c mc xung vi mt ngun khc c sut in ng ln hn.p n ng: D Cu 219 ( Cu hi ngn)

Nu ghp n ngun c cng l A: B: C: D:

,r song song vi nhau sut in ng v in tr trong ca b ngun

b = , rb = nr. b = , rb = r/n. b = n , rb = r/n. b = / n, rb = nr.


Nu ghp n ngun c cng ,r ni tip vi nhau sut in ng v in tr trong ca b ngun l A: B: C: D:

b = , rb = nr. b = , rb = r/n. b = n , rb = r/n. b = n , rb = nr.


Khi hai ngun in mc xung i vi nhau th sut in ng ca b bng

A: Tng sut in ng ca hai ngun. B: Hiu sut in ng hai ngun. C: Sut in ng ca ngun ln hn. D: Khng.p n ng: B Cu 222 ( Cu hi ngn)

Mun lm tng sut in ng v gim in tr trong ca ngun in. Ngi ta phi mc cc cc ngun ging nhau thnh b theo kiu : A: Ni tip. B: Xung i. C: Song song. D: Hn hp i xng.p n ng: D Cu 223 ( Cu hi ngn)

Nu c nhiu ngun in mc song song vi nhau th A: Cng ng dng in qua cc ngun phi bng nhau. B: Hiu sut cc ngun bng nhau. C: Hiu in th mi u hai ngun bng nhau. D: Lng in tch qua mi ngun trong cng mt thi gian bng nhau.p n ng: C

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Ren Ki Nang Vat Li 112 Danh Cho Gv Va Hs Kha Gioi