kiruchina 9 klass fizika

Ðîçâ’ÿçàííÿ âïðàâ òà çàâäàíü äî ï³äðó÷íèêà «Ô³çèêà» Ô. ß. Áîæèíîâî¿ òà ³í.

Ðîçä³ë 1. Åëåêòðè÷íå ïîëå

§ 1. Çàðÿä ³ åëåêòðîìàãí³òíà âçàºìîä³ÿ

Âïðàâà ¹ 1 1. Ïåðøà êóëüêà â³äøòîâõóºòüñÿ â³ä ïîçèòèâíî çàðÿäæåíî¿ êóë³, – òîìó ¿¿

çàðÿä ïîçèòèâíèé. Äðóãà ïðèòÿãóºòüñÿ, – òîìó ¿¿ çàðÿä íåãàòèâíèé. 2. Åáîí³òîâà ïàëè÷êà, ïîòåðòà âîâíîþ, íàáóâàº íåãàòèâíîãî çàðÿäó. Òðåáà

ï³äíåñòè ïàëè÷êó äî êóëüêè: ÿêùî êóëüêà â³äøòîâõóºòüñÿ – ¿¿ çàðÿä íåãàòèâíèé, ïðèòÿãóºòüñÿ – ïîçèòèâíèé.

3. Ó íåéòðàëüíîìó àòîì³ Ne = Np = 12; 12 2 10.eN ′ = − =4. Àòîì Ë³ò³þ ìàº 3 åëåêòðîíè. Ïîçèòèâíèé ³îí Ë³ò³þ ìîæå ìàòè 0, 1, 2

åëåêòðîíè, òîáòî àòîì âòðà÷àº 3, 2 ÷è 1 åëåêòðîí.

§ 2. Åëåêòðè÷íå ïîëå. Âçàºìîä³ÿ çàðÿäæåíèõ ò³ë

Âïðàâà ¹ 2 1. ×àñòèíêà ìîæå ìàòè çàðÿä, êðàòíèé |e|, òîáòî ±å = ±1,6 ⋅ 10—19 Êë. 8 ⋅ 10—19

Êë = 5 ⋅ |e| – ìîæëèâî, —2,4 ⋅ 10—19 Êë = 1,5å – íåìîæëèâî; 2,4 ⋅ 10—18 Êë = 15 ⋅ |e| – ìîæëèâî.

2. Äàíî: Ðîçâ’ÿçàííÿ: Q = 1 Êë |e| = 1,6 ⋅ 10—19 Êë N – ?

191810

6,25 10 .1,6

QN

e= = = ⋅

Â³äïîâ³äü: N = 6,25 ⋅ 1018 åëåìåíòàðíèõ çàðÿä³â. 3. Äàíî: Ðîçâ’ÿçàííÿ:

m = 0,3 ìã = 0,3 ⋅ 10—

6 êã g = 9,8 Í/êã F – ?

F = mg = 0,3 ⋅ 10—6 ⋅ 9,8 ≅ 3 ⋅ 10—6 (Í).

êã Í[ ] Í.

êãF

⋅= =

Â³äïîâ³äü: F = 3 ⋅ 10—6 Í.

§ 3. Ìåõàí³çì åëåêòðèçàö³¿. Åëåêòðîñêîï

Âïðàâà ¹ 3

1. Ìàñà çàðÿäæåíî¿ ïàëè÷êè çìåíøóºòüñÿ íà ìàñó åëåêòðîí³â, ÿê³ ïåðåéøëè

íà ïàï³ð ïðè òåðò³. 2. ßêùî åëåêòðîñêîï ìàâ çàðÿä Q ³ îòðèìàâ ïðè äîòèêó çàðÿä —Q, òî ï³ñëÿ

äîòèêó éîãî çàðÿä áóäå Q — Q = 0. 3. Ïîçèòèâíî çàðÿäæåí³ ñìóæêè åëåêòðîñêîïà ðîç³éøëèñÿ á³ëüøå, òîáòî ¿õ

ïîçèòèâíèé çàðÿä çá³ëüøèâñÿ. Öå ìîæå áóòè, ÿêùî åëåêòðîíè ïåðåéäóòü äî êîíäóêòîðà ï³ä âïëèâîì ïîëÿ ïîçèòèâíî çàðÿäæåíî¿ ïàëè÷êè.

4. Àíòèñòàòèê íà äåÿêèé ÷àñ íàäàº ìàòåð³àëó îäÿãó âëàñòèâîñò³ ïðîâ³äíèêà, òîáòî çàðÿä ñò³êàº ç îäÿãó.

1

5. Äàíî: Ðîçâ’ÿçàííÿ: q1 = 3 ⋅ 10—9 Êë q2 = —9 ⋅ 10—9 Êë

1 – ?q ′ 2 – ?q ′

1 2 ;q q′ ′= 1 2 1 2;q q q q′ ′+ = +9 9

91 21 2

3 10 9 103 10

2 2

q qq q

− −−+ ⋅ − ⋅′ ′= = = = − ⋅ (Êë).

Â³äïîâ³äü: Êë. 91 2 3 10q q −′ ′= = − ⋅

6. Ðîçïîâ³äü ïðî ïîæåæó ïðàâäîïîä³áíà: öèñòåðíà ìîæå åëåêòðèçóâàòèñÿ, â

ïàðàõ áåíçèíó ìîæå ïðîñêî÷èòè ³ñêðà. Ðîçïîâ³äü ïðî çàçåìëåííÿ íåïðàâäîïîä³áíà, öèñòåðíà, êîëåñà, ðåéêè – ïðîâ³äíèêè, ¿õ íå íåîáõ³äíî çàçåìëÿòè.

7. Ïðèïóñòèìî, ùî ïàëè÷êà çàðÿäæåíà

íåãàòèâíî. Ñïî÷àòêó åëåêòðîíè ã³ëüçè ïåðåì³ñòÿòüñÿ íà äàëüí³é â³ä ïàëè÷êè á³ê, ã³ëüçà ïðèòÿãíåòüñÿ äî ïàëè÷êè, òîðêíåòüñÿ ¿¿, ÷àñòèíà åëåêòðîí³â ç ïàëè÷êè ïåðåì³ñòèòüñÿ äî ã³ëüçè. Äâà íåãàòèâíî çàðÿäæåíèõ ò³ëà â³äøòîâõíóòüñÿ. ßêùî ïàëè÷êà ïîçèòèâíî çàðÿäæåíà, òî ã³ëüçà áóäå ïîâîäèòèñü òàê ñàìî, ò³ëüêè åëåêòðîíè áóäóòü ïåðå- ì³ùóâàòèñÿ â³ä ã³ëüçè äî ïàëè÷êè.

§ 4. Çàêîí Êóëîíà

1. Äàíî: Ðîçâ’ÿçàííÿ:

q1 = q2 1 ⋅ 10—4 Êë r = 1 ì k = 9 ⋅ 109 Íì2/Êë2 F – ?

9 4 41 22 9 10 10 10 90

q qF k

r− −= = ⋅ ⋅ ⋅ = (Í);

2

2 2

Í ì Êë Êë[ ] Í.

Êë ìF

⋅ ⋅ ⋅= =⋅

Â³äïîâ³äü: F = 90 Í. 2. Äàíî: Ðîçâ’ÿçàííÿ:

1 12q q′ =

2 22q q′ =

r′ = 4r

– ?FF′

1 22 ;

q qF k

r=

1 2 1 2 1 22 2 2

4.

16 4 4

q q q q q q FF k k k

r r r

′ ′= = = =′

′

Â³äïîâ³äü: ñèëà çìåíøèòüñÿ â 4 ðàçè.


F′ = 9F

1 1q q ′=

2 2q q ′=

– ?rr′

1 22 ;

q qF k

r=

21 2 1 2

2 2 2; 9;q q q q F r

F k kr r F r

′ ′ ′= = = =′′ ′ ′

2

9;rr⎛ ⎞ =⎜ ⎟⎝ ⎠′

3;rr

=′

1

.3

rr′ =

2

Â³äïîâ³äü: â³äñòàíü çìåíøèëàñü ó 3 ðàçè. 4. Äàíî: Ðîçâ’ÿçàííÿ:

q1 = q2 N = 1011 r = 10 ñì = 0,1 ì F – ?

1 22 ;

q qF k

r= q1 = q2 = Nå;

2 9 19 11 25

2 2

( ) 9 10 (1,6 10 10 )23 10

0,1

k NeF

r

−−⋅ ⋅ ⋅ ⋅ ⋅= = ≅ ⋅

(Í) = 2,3 ⋅ 10—4 (Í). Â³äïîâ³äü: F = 2,3 ⋅ 10—4 Í.


|q1| = 5|q2|

1 2q q q′ ′= = ′

– ?FF′

– ?FF′′

1) Êóëüêè çàðÿäæåí³ îäíîéìåííî:

1 2 1 2 ;q q q q′ ′+ = + 5q2 + q2 = 2q′; q′ = 3q2;

1 2 2 2 22 2

5 5;

q q q q kqF k k

r r r⋅

= = =

21 2 2 2

2 2 2r

2

(3 ) 9;

q q q kqF k k

r r

′ ′= = =′

91,8;

5

FF′ = = F′ = 1,8F.

2) Êóëüêè çàðÿäæåí³ ð³çíîéìåííî:

1 2 1 2 ;q q q q′ ′+ = + 5q2 — q2 = 2q′; 4q2 = 2q′; q′ = 2q2; 2

1 2 22 2

5;

q q kqF k

r r= =

2 22 2

2 2

(2 ) 4;

k q kqF

r r= =′′

40,8;

5

FF′′ = = F″ = 0,8F;

11,25.

0,8

FF

= =′′

Â³äïîâ³äü: ïðè îäíîéìåííî çàðÿäæåíèõ êóëüêàõ ñèëà âçàºìîä³¿ çá³ëüøèòüñÿ â 1,8 ðàç³â; ïðè ð³çíîéìåííî çàðÿäæåíèõ – çìåíøèòüñÿ â 1,25 ðàç³â.

Çàâäàííÿ äëÿ ñàìîïåðåâ³ðêè çà ðîçä³ëîì 1 «Åëåêòðè÷íå ïîëå»


1

2

16FF

=

1

2

– ?rr

1 21 2

1

;q q

F kr

= 1 22 2

2

;q q

F kr

=

2

1 2

2 1

16;F rF r

⎛ ⎞= =⎜ ⎟⎝ ⎠

2

1

4;rr

= 1

2

1.

4

rr

=

Â³äïîâ³äü: â³äñòàíü çá³ëüøèëàñü âó4 ðàçè. 12. Äàíî: Ðîçâ’ÿçàííÿ:

1 13q q′ =

2 23q q′ =

– ?FF′

1 22

;q q

F kr

⋅=

1 21 2 1 2

2 2 2

3 39 9

q q q q q q;F k k k

r r r

′ ′⋅ ⋅ ⋅ ⋅= = = =′ F

9.FF′ =

Â³äïîâ³äü: ñèëà âçàºìîä³¿ çá³ëüøèòüñÿ

3

ó 9 ðàç³â. 13. Äàíî: Ðîçâ’ÿçàííÿ:

q1 = 2 ⋅ 10—5 Êë r = 6 ñì = 0,6 ì F = 0,1 Í q2 – ?

1 22 ;

q qF k

r=

2

21

;Fr

qkq

= 2

2 2

2

Í ì[ ] Êë;

Í ìÊë

Êë

q⋅= =

⋅ ⋅

3

92 9 5

0,1 3,6 102 10

9 10 2 10q

−−

−

⋅ ⋅= =⋅ ⋅ ⋅

⋅ (Êë).

Â³äïîâ³äü: q2 = 2 ⋅ 10—9 Êë. 14. Äàíî: Ðîçâ’ÿçàííÿ:

q1 = —4 ìêÊë = —4 ⋅ 10—6 Êë r = 8 ñì = 8 ⋅ 10—2 ì F = 0,9 Í N – ?

2 ;q

Ne

= 1 22 ;

q qF k

r=

2

21

;Fr

qkq

=

2

2 2

2

Í ì[ ] Êë;

Í ìÊë

Êë

q⋅= =

⋅ ⋅

47

2 9 6

0,9 64 101,6 10

9 10 4 10q

−−

−

⋅ ⋅= = −⋅ ⋅ ⋅

⋅ Êë;

712

19

1,6 1010 .

1,6 10N

−

−

− ⋅= =− ⋅

Â³äïîâ³äü: 1012 åëåêòðîí³â. 15. Äàíî: Ðîçâ’ÿçàííÿ:

q1 = 1,8 ⋅ 10—8 Êë q2 = —0,3 ⋅ 10—8 Êë q3 = 0 r = 5 ñì = 5 ⋅ 10—2 ì

1 – ?q ′ q 2 – ?′

3 – ?q ′ F′ – ?

1 2 3 1 2 3 ;q q q q q q′ ′ ′+ + = + + 1 2 3 ;q q q q′ ′ ′= = = ′8 8

81 2 3 1,8 10 0,3 100,5 10

3 3

q q qq

− −−+ + ⋅ − ⋅= = =′ ⋅ (Êë);

2 9 165

2 46

9 10 0,25 109 10

25 10

qF k

r

−−

−

⋅ ⋅ ⋅′= = = ⋅′⋅

(Í) =

= 90 (ìêÍ). Â³äïîâ³äü: q′ = 0,5 ⋅ 10—8 Êë; F′ = 90 ìêÍ.

Ðîçä³ë 2. Åëåêòðè÷íèé ñòðóì

§ 8. Åëåêòðè÷íå êîëî òà éîãî åëåìåíòè

Âïðàâà ¹ 8

1. 2.

4

3. 4. 5. 6.

§ 9. Ñèëà ñòðóìó. Îäèíèö³ ñèëè ñòðóìó. Àìïåðìåòð

Âïðàâà ¹ 9 1. à) 0,1 À; I = 0,2 À; á) 0,5 ìÀ; I = 4,5 ìÀ; â) 0,2 À; I = 1,8 À. 2. Àìïåðìåòð ìîæíà ïðèºäíàòè â áóäü-ÿêîìó ì³ñò³ ïîñë³äîâíîãî êîëà. 3. Äàíî: Ðîçâ’ÿçàííÿ:

I = 200 ìÀ = 0,2 À q = 24 Êë t – ?

;q

It

= ;q

tI

= Êë À ñ

[ ] ñ;À À

t⋅= = =

24

1200,2

t = = ñ = 2 (õâ.).

Â³äïîâ³äü: t = 2 õâ. 4. Äàíî: Ðîçâ’ÿçàííÿ:

I = 3 À t = 15 õâ = 900 ñ Q – ?

;Q

It

= Q = I ⋅ t; [Q] = À ⋅ ñ = Êë; Q =

= 3 ⋅ 900 = 2700 (Êë).

5

Â³äïîâ³äü: Q = 2700 Êë. 5. Äàíî: Ðîçâ’ÿçàííÿ:

I = 0,2 À t = 10 õâ = 600 ñ Q – ?

;Q

It

= Q = I ⋅ t; [Q] = À ⋅ ñ = Êë;

Q = 0,2 ⋅ 600 = 120 Êë. Â³äïîâ³äü: Q = 120 Êë.


t = 10 ñ N = 2 ⋅ 1020 I – ?

;Q

It

= Q = N|e|; ;Ne

It

= Êë

[ ] À;ñ

I = =

20 192 10 1,6 103,2 (À).

10I

−⋅ ⋅ ⋅= =

Â³äïîâ³äü: I = 3,2 À.

§ 10. Åëåêòðè÷íà íàïðóãà, îäèíèöÿ íàïðóãè, âîëüòìåòð

Âïðàâà ¹ 10

1. à) 10 0

110VC−= = (Â); U = 4 Â; 2.

á) 5 0

0,510VC−= = (Â); U = 6 Â;

â) 5 0

15VC−= = (Â); U = 8 Â.


q = 3 Êë A = 0,12 êÄæ U – ?

A = U ⋅ q; 120

40;3

AU

q= = =

Äæ[ ] Â.

ÊëU = =

Â³äïîâ³äü: U = 40 Â. 4. Äàíî: Ðîçâ’ÿçàííÿ:

q = 4 Êë U = 5 Â A – ?

A = U ⋅ q; [A] = Â ⋅ Êë = Äæ; F = 12 ⋅ 4 = 48 Äæ. Â³äïîâ³äü: À = 48 Äæ.


q = 60 Êë m = 200 ã = 0,2 êã h = 360 ì U – ?

A1 = q ⋅ U; A2 = mgh; A1 = A2; q ⋅ U = mgh;

;mgh

Uq

=

Íêã ì Í ì Äæêã[ ] Â;

Êë Êë ÊëU

⋅ ⋅ ⋅= = = =

0,2 10 36012 Â.

60U

⋅ ⋅= =

6

Â³äïîâ³äü: U = 12 Â. § 11. Åëåêòðè÷íèé îï³ð. Çàêîí Îìà

Âïðàâà ¹ 11

1. ;U

IR

= ;U

RI

= I R = 3 Îì; II R = 3,3 Îì; III R = 5 Îì; IV R = 10 Îì.

2. Äàíî: Ðîçâ’ÿçàííÿ: I = 1,5 À R = 150 Îì U – ?

U = I ⋅ R = 1,5 ⋅ 150 = 225 (Â). Â³äïîâ³äü: U = 225 Â.


U = 12 Â I = 0,6 À U1 = 6 Â U2 = 20 Â U3 = 1 Â I1 – ? I2 – ? I3 – ?

;U

IR

= 12

200,6

UR

I= = = (Îì);

11

60,3

20

UI

R= = = (À); 2

2

201

20

UI

R= = = (À);

33

10,05

20

UI

R= = = (À).

Â³äïîâ³äü: 0,3 À; 1 À; 0,05 À. 4. Äàíî: Ðîçâ’ÿçàííÿ:

U = 120 Â I = 15 ìÀ = 15 ⋅ 10—3 À R – ?

;U

IR

= 3

1208000

15 10

UR

I −= = =⋅

(Îì) = 8 (êÎì).

Â³äïîâ³äü: R = 8 êÎì.

5. R = 2 Îì; 0,5 ;2

U UI U

R= = =

U (Â) 0 2 4… I (À) 0 1 2…


U = 12 Â t = 5 õâ = 300 ñ q = 60 Êë R – ?

;U

IR

= ;U

RI

= ;q

It

= ;Ut

Rq

=

Â Êë[ ] Îì;

ñR

⋅= = 12 300

6060

R⋅= = (Îì).

Â³äïîâ³äü: R = 60 Îì. 7. Äàíî: Ðîçâ’ÿçàííÿ:

I = 1,2 À U = 18 Â R – ?

;U

IR

= 18

151,2

UR

I= = = (Îì).

Â³äïîâ³äü: R = 15 Îì.

7


U = 6 Â R = 1,5 Îì N = 16 CA – ?

;A

IC

N=

64

1,5

UI

R= = = (À);

40,25

16AC = = (À).

Â³äïîâ³äü: CA = 0,25 À.

9. .l

RS

= ρ Îï³ð ïðîâ³äíèêà çàëåæèòü â³ä éîãî ðîçì³ðó ³ ìàòåð³àëó.

§ 12. Ïèòîìèé îï³ð ðå÷îâèíè

Âïðàâà ¹ 12


Rç = Rì = Rñ Sç = Sì = Sñ ρñ > ρç > ρì

lç, lì, lñ – ?

;l

RS

= ρ S = const; ρñ ⋅ lñ = ρç ⋅ lç = ρì ⋅ lì;

ρñ > ρç > ρì; lñ > lç > lì. Â³äïîâ³äü: 3 – ñâèíåöü, 2 – çàë³çî, 1 – ì³äü.


l = 1 êì = 103 ì S = 0,68 ñì2 = 68 ìì2 ρ = 0,017 (Îì⋅ìì2)/ì R – ?

;l

RS

= ρ 2

2

Îì ìì ì[ ] Îì;

ì ììR

⋅= ⋅ =

30,017 100,25

68R

⋅= = (Îì).

Â³äïîâ³äü: R = 0,25 Îì. 4. Äàíî: Ðîçâ’ÿçàííÿ:

R = 25 Îì l1 = 0,5l S1 = 2S R1 – ?

;l

RSρ= 1

11

0,50,25 0,25 ;

2

l l lR R

S S Sρ ρ ρ= = = = R1 = 0,25 R.

Â³äïîâ³äü: îï³ð çìåíøèâñÿ ó 4 ðàçè.

5. I = 1,4 À; U = 4,2 Â; 4,2

31,4

UR

I= = = (Îì).

Ïðè ïåðåñóâàíí³ ïîâçóíêà ðåîñòàòà âïðàâî éîãî îï³ð çìåíøèòüñÿ, íàïðóãà íå çì³íèòüñÿ, ñòðóì çá³ëüøèòüñÿ. 6. Äàíî: Ðîçâ’ÿçàííÿ:

S = 0,2 ìì2 ρ = 1,1 (Îì⋅ìì2)/ì I = 0,4 À U = 4,4 Â l – ?

;l

RSρ= ;

RSl =

ρ ;

UR

I= ;

USl

I=

ρ

2 2

2 2

Â ìì Îì ìì ì[ ] = = ì;

Îì ìì Îì ììÀ

ì

l⋅ ⋅ ⋅=

⋅ ⋅⋅

4,4 0,22

0,4 1,1l

⋅= =⋅

(ì).

8

Â³äïîâ³äü: l = 2 ì. 7. Äàíî: Ðîçâ’ÿçàííÿ:

I = 15 À l = 10 ì U = 0,85 Â ρ = 0,017 (Îì⋅ìì2)/ì d – ?

2

;4

dS

π= 2 ;S

d =π

;l

RSρ= ;

l lIS

R Uρ ρ= =

2 ;lI

dUρ=π

2 2Îì ìì À ì Îì ìì[ ] ìì;

ì Â Îìd

⋅ ⋅ ⋅ ⋅= =⋅

=

0,017 10 152 2

0,85 3,14d

⋅ ⋅= ≅⋅

(ìì).

Â³äïîâ³äü: d = 2 ìì. 8. Äàíî: Ðîçâ’ÿçàííÿ:

l = 100 ì U = 1 Â I = 15 À ρ = 0,028 (Îì⋅ìì2)/ì η = 2700 êã/ì3 m – ?

m = η ⋅ V = η ⋅ l ⋅ S; ;l

RSρ= ;

l lIS

R Uρ ρ= =

2 22Îì ìì ì À Îì ìì

[ ] ìì ;ì Â Îì

S⋅ ⋅ ⋅ ⋅= =

⋅=

0,028 100 1542

1S

⋅ ⋅= = ìì2 = 42 ⋅ 10—6 ì2.

23

êã[ ] ì ì êã;

ìm = ⋅ ⋅ =

m = 2700 ⋅ 100 ⋅ 42 ⋅ 10—6 = 11,34 (êã). Â³äïîâ³äü: m = 11,34 êã.

Âïðàâà ¹ 13


R = 65 Îì R1 = R2 = 15 Îì R3 – ?

R = R1 + R2 + R3; R3 = R — R1 — R2 = 65 — 15 — 15 = = 35 (Îì). Â³äïîâ³äü: îï³ð ðåîñòàòà 35 Îì.


R1 = 15 Îì R2 = 10 Îì U = 100 Â U1 – ?

U1 = I⋅ R1; 1 2

;U

IR R

=+

11

1 2

;UR

UR R

=+

1

Â Îì[ ] Â;

Îì + ÎìU

⋅= = 1

100 1560

25U

⋅= = (Â).

Â³äïîâ³äü: íàïðóãà ì³æ êëåìàìè k1 ³ k2 60 Â. 3. Äàíî: Ðîçâ’ÿçàííÿ:

I1 = 0,3 À U = 220 Â R = 1100 Îì I – ?

2200,2

1100

UI

R= = = (À) – òàêèé ñòðóì ïîòå÷å êð³çü

ïîñë³äîâíî ç’ºäíàí³ ëàìïè. I < I1, òîìó ëàìïó äëÿ ë³õòàðèêà òàê ìîæíà âìèêàòè. Â³äïîâ³äü: ìîæíà.

9


R1 = 650 Îì I = 80 ìÀ = 0,08 À U = 72 Â R2 – ?

R = R1 + R2; R2 = R — R1; ;U

IR

= ;U

RI

=

2 1;U

R RI

= − 2

72650 250

0,08R = − = (Îì).

Â³äïîâ³äü: 250 Îì. 5. Äàíî: Ðîçâ’ÿçàííÿ:

R1 = 5 Îì R2 = 8 Îì R3 = 15 Îì U2 = 1,6 Â I – ? U – ?

22

2

1,60,2

8

UI I

R= = = = (À); U = I ⋅ R; R = R1 + R2 + R3;

U = I ⋅ (R1 + R2 + R3) = 0,2 ⋅ (5 + 8 + 15) = 5,6 (Â). Â³äïîâ³äü: I = 0,2 À; U = 5,6 Â.

§ Âïðàâà ¹ 14

1. 2. Äàíî: Ðîçâ’ÿçàííÿ:

R1 = 100 Îì R2 = 150 Îì I = 2,4 À U – ?

U = I ⋅ R; 1 2

1 1 1 1 10,0167;

100 150R R R= + = + =

1

600,0167

R = ≅ (Îì); U = 2,4 ⋅ 60 ≅ 144 (Â).

Â³äïîâ³äü: U = 144 Â. 3. Äàíî: Ðîçâ’ÿçàííÿ:

U = 120 Â R1 = 200 Îì R2 = 300 Îì I – ? I1 – ? I2 – ?

;U

IR

=

1 2

1 1 1 1 10,005 0,0033 0,0083;

200 300R R R= + = + = + =

1120

0,0083R = ≅ (Îì);

1201

120I = = (À);

U1 = U2 = U; 11

1 1

1200,6

200

U UI

R R= = = = (À);

22

2 2

1200,4

300

U UI

R R= = = = (À).

Â³äïîâ³äü: I = 1 À; I1 = 0,6 À; I2 = 0,4 À.

10


ρç > ρì > ρñ

Iç – ? Iì – ? Iñ – ? ;

UI

R= U1 = U2 = U3 = U; з

з

;U

IR

= ìì

;U

IR

=

ññ

;U

IR

= ;l

RSρ= Rç > Rì > Rñ; Iç > Iì > Iñ.

Â³äïîâ³äü: ó ñð³áíîìó äðîò³ ñèëà ñòðóìó á³ëüøà.

5. Äàíî: Ðîçâ’ÿçàííÿ: R1 = 2 Îì R2 = 3 Îì R3 = R4 = 4 Îì R5 = 0,8 Îì U = 4 Â

R – ? I – ? åêâ³âàëåíòà åëåêòðè÷íà ñõåìà

6 1 2

1 1 1 1 10,83;

2 3R R R= + = + = R6 = 1,2 (Îì);

7 3 4

1 1 1 1 1 1;

4 4 2R R R= + = + = R7 = 2 (Îì);

T = R5 + R6 + R7 = 0,8 + 1,2 + 2 = 4 (Îì);

41

4

UI

R= = = (À).

Â³äïîâ³äü: R = 4 Îì; I = 1 À. 6. Äàíî: Ðîçâ’ÿçàííÿ:

R1 = 3 Îì R2 = 2 Îì R3 = 8 Îì I3 = 0,1 À U – ?

U3 = I3 ⋅ R3 = 0,1 ⋅ 8 = 0,8 (Â); U3 = U2 = 0,8 Â;

22

2

0,80,4

2

UI

R= = = (À); I1 = I2 + I3 = 0,4 + 0,1 = 0,5 (À);

U = I ⋅ R = 0,5 ⋅ 3 = 1,5 (Â); U = U1 1 1

= 2,3 (Â). 1 + U2 = 1,5 + 0,8 =

Â³äïîâ³äü: U = 2,3 Â.

Âïðàâà ¹ 15 1. Äàíî: Ðîçâ’ÿçàííÿ:

Àê = 2174 êÂò⋅ãîä Àï = 1298 êÂò⋅ãîä Â = 24,36 êîï/(êÂò⋅ãîä) À – ? Ã – ?

À = Àê — Àï = 2174 — 1298 = 876 (êÂò⋅ãîä); Ã = À ⋅ Â = 876 ⋅ 24,36 = 21 339 (êîï.) = = 213 ãðí. 30 êîï. Â³äïîâ³äü: À = 876 êÂò⋅ãîä; Ã = 213 ãðí. 39 êîï.

11

2. A = U ⋅ I ⋅ t; [A] = Äæ; [U ⋅ I ⋅ t] = Â ⋅ À ⋅ ñ. 3. Äàíî: Ðîçâ’ÿçàííÿ:

I = 0,8 À U = 3,4 Â t = 15 õâ = 900 ñ A – ?

A = U ⋅ I ⋅ t = 3,4 ⋅ 0,8 ⋅ 900 = 2448 (Äæ) = = 2,448 (êÄæ). Â³äïîâ³äü: A = 2,448 êÄæ.


R1 = 10 Îì R2 = 25 Îì U = 100 Â t = 5 õâ = 300 ñ A1 – ? A2 – ? A3 – ? A4 – ?

à) Ïàðàëåëüíå ç’ºäíàííÿ ïðîâ³äíèê³â: 2

;U

A UIt tR

= =

2 2

11

100300 300 000

10

UA t

R= = ⋅ = (Äæ) = 300 (êÄæ);

2 2

22

100300 120 000

25

UA t

R= = ⋅ = (Äæ) = 120 (êÄæ).

á) Ïîñë³äîâíå ç’ºäíàííÿ ïðîâ³äíèê³â:

R = R1 + R2 = 10 + 25 = 35 Îì; 100

2,8635

UI

R= = = (À); A = UIt = I2 Rt;

A3 = I2 R1t = 2,862 ⋅ 10 ⋅ 300 ≅ 24 490 (Äæ) ≅ 24,5 (êÄæ); A4 = I2R2t = 2,862 ⋅ 25 ⋅ 300 = 61,2 (êÄæ). Â³äïîâ³äü: à) 300 êÄæ; 120 êÄæ; á) 24,5 êÄæ; 61,2 êÄæ.


P1 = 90 Âò P2 = 40 Âò U = 220 Â I1 – ? I2 – ? R1 – ? R2 – ?

2

;U

P UIR

= = 2

11

;U

PR

= 2 2

11

220538

90

UP

R= = = (Îì);

2 2

22

2201210

40

UP

R= = = (Îì); 1

1

2200,41

538

UI

R= = = (À);

22

2200,18

1210

UI

R= = = (À).

Â³äïîâ³äü: I1 = 0,41 À; I2 = 0,18 À; R1 = 538 Îì; R2 = 1210 Îì.


m = 1 ò = 103 êã h = 19 ì t = 50 ñ η = 80 % U = 380 Â I – ?

êîð.

ïîâí.

;A

Aη = Aêîð. = mgh; Aïîâíà = UIt; ;

mghUIt

η =

310 10 1912,5

380 50 0,8

mghI

Ut⋅ ⋅= = =

η ⋅ ⋅ (À);

êã ì Í Í ì Äæ êã[ ] = = = À.

Äæêã Â ñ Äæ ññÊë

I⋅ ⋅ ⋅= ⋅⋅ ⋅ ⋅

Â³äïîâ³äü: I = 12,5 À.

12

*7. Äàíî: Ðîçâ’ÿçàííÿ:

U = 127 Â P = 50 Âò U1 = 220 Â R – ?

P = UI; 50

0,39127

PI

U= = = (À);

U1 — U = IR;

1 220 127238

0,39

U UR

I− −= = =

(Îì). Â³äïîâ³äü: R = 238 Îì.

8*. Äàíî: Ðîçâ’ÿçàííÿ:

R1 = R2 = R Pïîñë. – ? Pïàð. – ?

2

;U

P UIR

= = 2

ïîñë.ïîñë.

;U

PR

= Rïîñë. = R1 + R2 = 2R;

2

ïîñë. ;2

UR

R=

2

ïàð.ïàð.

;U

PR

= ïàð. 1 2

1 1 1 2;

R R R R= + =

2

ïàð.

2;

UP

R= ïàð.

ïîñë.

4.R

P=

Â³äïîâ³äü: ïàð

ïîñ

4.R

P=

Âïðàâà ¹ 16

1. Q = I2Rt; Râîëîñêà Rïðîâîä³â; Qâîëîñêà Qïðîâîä³â. 2. Äàíî: Ðîçâ’ÿçàííÿ:

R = 30 Îì I = 4 À t = 10 õâ = 600 ñ Q – ?

Q = I2Rt = 42 ⋅ 30 ⋅ 600 = 288 000 (Äæ) = 288 (êÄæ). Â³äïîâ³äü: Q = 288 êÄæ.


R1 = 10 Îì R2 = 20 Îì U = 100 Â t = 5 ñ Q1 – ? Q2 – ?

2

;U

Q tR

= 2 2

11

1005 5000

10

UQ t

R= = ⋅ = (Äæ) =

= 5 (êÄæ); 2 2

22

1005 2500

20

UQ t

R= = ⋅ = (Äæ) =

= 2,5 (êÄæ). Â³äïîâ³äü: Q1 = 5 êÄæ; Q2 = 2,5 êÄæ.


t1° = 20 °Ñ t2° = 100 °Ñ V = 1,5 ë P = 600 Âò η = 80 % t – ?

Qêîð = ηQïîâíà; Qïîâíà = Pt; Qêîð = cm(t2° — t1°); cm(t2° — t1°) = ηPt;

2 1( ) 4200 1,5 (100 20)1050

0,8 600

cm t tt

P° − ° ⋅ ⋅ −= = =η ⋅

(ñ).

Â³äïîâ³äü: t = 1050 ñ.

13


t = 5 õâ = 6000 ñ m = 0,2 êã t1° = 14 °Ñ t2° = 100 °Ñ I = 2 À U – ?

Q = UIt; Q = cm(t2° — t1°);

2 1( ) 4200 0,2 (100 14)120

2 300

cm t tQU

It It° − ° ⋅ ⋅ −= = = =

⋅ (Â).

Â³äïîâ³äü: U = 120 Â.

*6. Äàíî: Ðîçâ’ÿçàííÿ:

U = 120 Â Q = 1 ÌÄæ = 106 Äæ t = 1 ãîä = 3600 ñ d = 0,5 ìì ρ = 1,1 (Îì⋅ìì2)/ì l – ?

2

;U t

QR

= 2

;U t

RQ

= 2

4;

l lR

S dρ ρ= =

π

2 2 2 2

6

3,14 0,25 120 36009,2

4 4 4 1,1 10

d R d U tl

Qπ π ⋅ ⋅ ⋅= = = =

ρ ρ ⋅ ⋅ (ì).

Â³äïîâ³äü: l = 9,2 ì.

Âïðàâà ¹ 17 4. Äàíî: Ðîçâ’ÿçàííÿ:

Imax = 6 À U = 220 Â Pmax – ?

Pmax = UImax = 220 ⋅ 6 = 1320 (Âò) = 1,32 (êÂò). Â³äïîâ³äü: Pmax = 1,32 êÂò.

Âïðàâà ¹ 18

1. Êîòóøêà ç äðîòîì îáåðòàºòüñÿ çà ãîäèííèêîâîþ ñòð³ëêîþ, ï³ñëÿ ¿¿

çóïèíêè åëåêòðîíè â äðîò³ òàêîæ çà ³íåðö³ºþ áóäóòü ðóõàòèñÿ çà ãîäèííèêîâîþ ñòð³ëêîþ. Íàïðÿì ñòðóìó – ïðîòèëåæíèé (öå íàïðÿì ðóõó ïîçèòðîí³â).

2. Â³äîìî, ùî ïèòîìèé îï³ð (à ç íèì ³ îï³ð) ïðîâ³äíèê³â çá³ëüøóºòüñÿ ç

íàãð³âàííÿì. 2

;U

Q tR

= .l

RSρ= ßêùî â ã³ïîòåòè÷í³é ïëèòö³ Q2 = Q ïðè

R2 = R ³ ρ2 = ρ, òðåáà çá³ëüøèòè äîâæèíó ñï³ðàë³ l2 > l. *3. Ó ìîìåíò âìèêàííÿ âîëîñîê íå ðîç³ãð³òèé, éîãî îï³ð ì³í³ìàëüíèé, ñèëà

ñòðóìó – ìàêñèìàëüíà.

Âïðàâà ¹ 19

1. m = kIt = kq; ;m

kq

= êã

[ ] .Êë

k =

2. Ó âîäîïðîâ³äí³é, ð³÷êîâ³é òà ìîðñüê³é âîä³ º ð³çíîìàí³òí³ äîì³øêè, ÿê³ ðîçïàäàþòüñÿ íà éîíè, ðîç÷èí ïðîâîäèòü ñòðóì.

3. Ìîëåêóëè ñîë³ ðîçïàäàþòüñÿ ó âîä³ íà ³îíè, à ìîëåêóëè öóêðó íå ðîçïàäàþòüñÿ.


m = 25 ã I = 0,5 À k = 1,2 ìã/Êë t – ?

m = kIt; 3

325 1044,6 10 (ñ)

1,12 0,5

mt

kI⋅= = = ⋅⋅

=

= 44 600 ñ = 744 õâ = 12,4 (ãîä). Â³äïîâ³äü: t = 12,4 ãîä.

14


t = 2 ãîä = 7200 ñ U = 2 Â R = 0,4 Îì k = 1,2 ìã/Êë m – ?

1,12 2 720040 320

0,4

kUtm kIt

R⋅ ⋅= = = = (ìã) =

= 40,32 (ã). Â³äïîâ³äü: m = 40,32 ã.


t = 50 õâ = 3000 ñ m = 3 ã = 3000 ìã R = 0,4 Îì k = 1,12 ìã/Êë P – ?

m = kIt; 3000

0,91,12 3000

mI

kt= = =

⋅ (À);

P = UI = I2R = 0,92 ⋅ 0,4 ≅ 0,32 (Âò). Â³äïîâ³äü: P = 0,32 Âò.

Âïðàâà ¹ 20


I = 1,4 À U = 11 Â k = 1,12 ìã/Êë = 1,12 ⋅ 10—6 êã/Êë ρ = 10,5 ã/ñì3 = 10,5 ⋅ 103 êã/ì3 S = 0,03 ì2 d = 8 ìêì = 8 ⋅ 10—6 ì t – ? A – ?

m = kIt; ;m

tkI

= m = ρV = ρSd;

3 6

6

10,5 10 0,03 8 10

1,12 10 1,4

Sdt

kI

−

−

ρ ⋅ ⋅ ⋅ ⋅= =⋅ ⋅

=

(ñ) = 26,8 õâ; 31,6 10= ⋅A = UIt = 11 ⋅ 1,4 ⋅ 1,6 ⋅ 103 = = 24,6 ⋅ 103 (Äæ) = 24,6 (êÄæ). Â³äïîâ³äü: t = 26,8 õâ; A = 24,6 êÄæ.


I = 0,48 À t = 15 õâ = 900 ñ S = 0,01 ì2 ρ = 7,1 ã/ñì3 = 7,1 ⋅ 103 êã/ì3 k = 0,34 ìã/Êë = 0,34 ⋅ 10—6 êã/Êë d – ?

m = kIt; m = ρSd; 6

3

0,34 10 0,48 900

7,1 10 0,01

m kItd

S S

−⋅ ⋅ ⋅= = =ρ ρ ⋅ ⋅

=

(ì) = 2 (ìêì). 62 10−= ⋅Â³äïîâ³äü: d = 2 ìêì.

3. Äàíî: Ðîçâ’ÿçàííÿ: I = 1,8 À S = 50 ñì2 = 5 ⋅ 10—3 ì2 N = 12 d = 58 ìêì = 58 ⋅ 10—6 ì ρ = 10,5 ã/ñì3 = 10,5 ⋅ 103 êã/ì3 k = 1,12 ìã/Êë = 1,12 ⋅ 10—6 êã/Êë t – ?

m = kIt; ;m

tkI

= m = NρSd;

;N Sd

tkIρ=

3 3 6

6

12 10,5 10 5 10 58 10

1,12 10 1,8t

− −

−

⋅ ⋅ ⋅ ⋅ ⋅ ⋅= =⋅ ⋅

= 18 000 (ñ) = 5 (ãîä). Â³äïîâ³äü: t = 5 ãîä.

15

Âïðàâà ¹ 21

1. 2. Ï³ä ä³ºþ ìàãí³òíîãî ïîëÿ ìàãí³òà íà áëèæ÷îìó äî íüîãî áîö³ êóëüêè

ñòâîðèòüñÿ ï³âí³÷íèé ìàãí³òíèé ïîëþñ, êóëüêà ïðèòÿãíåòüñÿ äî ìàãí³òà. 3. Ó ìàãí³òíîìó ïîë³ êîæåí îøóðîê ñàì ñòàº ìàãí³òîì. Äî ïîëþñó ìàãí³òà

ïðèòÿãóþòüñÿ ð³çíîéìåíí³ ç íèì ïîëþñè îøóðê³â, à îäíîéìåíí³ â³äøòîâõóþòüñÿ ì³æ ñîáîþ.

4. Êîæåí çàë³çíèé ïðåäìåò ó ìàãí³òíîìó ïîë³ ïîñò³éíîãî ìàãí³òà ñàì ñòàº ìàãí³òîì ³, ó ñâîþ ÷åðãó, ïðèòÿãóº ³íøèé çàë³çíèé ïðåäìåò – ñòâîðþºòüñÿ ëàíöþæîê.

5. Ïðèïóñòèìî, ùî ïëàñòèíà 1 çàðÿäæåíà, 2 – í³. Ï³äíåñåìî ïë. 1 áóäü-ÿêèì ê³íöåì äî ñåðåäèíè ïë. 2 – â³äáóäåòüñÿ ïðèòÿãàííÿ. Òåïåð ïðèïóñòèìî, ùî ïëàñòèíà 1 íåçàðÿäæåíà, 2 – çàðÿäæåíà. Ï³äíåñåìî çíîâ ïë. 1 áóäü-ÿêèì ê³íöåì äî ñåðåäèíà ïë. 2 – ïðèòÿãàííÿ íå â³äáóäåòüñÿ.

Âïðàâà ¹ 22 1. Íà Ï³âí³÷íîìó ïîëþñ³ Çåìë³. 2. Òîìó ùî âîíè çíàõîäÿòüñÿ â ìàãí³òíîìó ïîë³ Çåìë³. 3. Öåé ìàòåð³àë ïîâèíåí íå íàìàãí³÷óâàòèñÿ â ìàãí³òíîìó ïîë³ Çåìë³.

Âïðàâà ¹ 23 1. 2. 3. 4.

16

5. 6.

à) â³äøòîâõíåòüñÿ á) ïðèòÿãíåòüñÿ

Âïðàâà ¹ 24

1. Íàïðÿìîê ñòðóìó – â³ä «+» äî «—». Ïîëþñè

ìàãí³òó âèçíà÷àºìî çà äîïîìîãîþ ïðàâèëà ïðàâî¿ ðóêè.

2. Äî B ³ C – êîòóøêà ñòàíå åëåêòðîìàãí³òîì. 3. Ë³âà ÷àñòèíà ñõåìè àâòîìàòà –

åëåêòðîìàãí³ò, ìàãí³òíå ïîëå ÿêîãî çàëåæèòü â³ä ñèëè ñòðóìó â êîë³ ìàãí³òà. Ñèëà ñòðóìó çàëåæèòü â³ä îïîðó ïðîâ³äíèê³â, ÿêèé, ó ñâîþ ÷åðãó çàëåæèòü â³ä òåìïåðàòóðè. Ïðè ïåâí³é òåìïåðàòóð³ ÿê³ð ó ïðàâ³é ÷àñòèí³ ñõåìè àâòîìàòà çàìêíå åëåêòðè÷íå êîëî äçâ³íêà, äçâ³íîê çàäçâåíèòü. Ïðèñòð³é ìîæíà âèêîðèñòîâóâàòè ó ïðèì³ùåííÿõ, äå ïîòð³áíî ï³äòðèìóâàòè ïîñò³éíó òåìïåðàòóðó, íàïðèêëàä, â îâî÷åñõîâèùàõ.

4. Ïðè ïåðåñóâàíí³ ïîâçóíêà ðåîñòàòà ïðàâîðó÷ îï³ð ðåîñòàòà ³ âñüîãî êîëà åëåêòðîìàãí³òà çìåíøèòüñÿ, ñòðóì çá³ëüøèòüñÿ, ï³ä³éìàëüíà ñèëà åëåêòðîìàãí³òà òàêîæ çá³ëüøèòüñÿ.

Âïðàâà ¹ 25 1. Íàïðÿìîê ñòðóìó â ïðîâ³äíèêó – â³ä «+» äî «—»,

íàïðÿìîê â³äõèëåííÿ çá³ãàºòüñÿ ç íàïðÿìêîì ñèëè Àìïåðà, íàïðÿìîê ìàãí³òíîãî ïîëÿ (³ ïîëþñè ìàãí³òà) âèçíà÷àºìî çà äîïîìîãîþ ïðàâèëà ë³âî¿ ðóêè.

2. Çà äîïîìîãîþ ïðàâèëà ë³âî¿ ðóêè âèçíà÷àºìî

íàïðÿìîê ìàãí³òíîãî ïîëÿ ³ ïîëþñè ìàãí³òà.

17

3. Çà äîïîìîãîþ ïðàâèëà ë³âî¿ ðóêè âèçíà÷àºìî íàïðÿìîê

ñèëè Àìïåðà ³ ðóõó àëþì³í³ºâîãî ñòðèæíÿ. 4. Êîðèñòóºìîñÿ ïðàâèëîì ë³âî¿ ðóêè äëÿ

ë³âî¿ òà ïðàâî¿ ÷àñòèí ðàìêè. Çà â³äîìèìè íàïðÿìàìè ìàãí³òíîãî ïîëÿ òà FA âèçíà÷àºìî íàïðÿì ñòðóìó.

5. Ïðîâ³äíèê 1 çíàõîäèòüñÿ â ìàãí³òíîìó ïîë³

ïðîâ³äíèêà 2. Âèçíà÷àºìî íàïðÿìîê ìàãí³òíîãî ïîëÿ ïðîâ³äíèêà 2 çà ïðàâèëîì ñâåðäëèêà. Çà ïðàâèëîì ë³âî¿ ðóêè âèçíà÷àºìî íàïðÿìîê ñèëè Àìïåðà, ÿêà ä³º â öüîìó ïîë³ íà ïðîâ³äíèê 1.

7. Ï³ñëÿ çàìèêàííÿ êëþ÷à ïî âñüîìó êîëó ïîòå÷å ñòðóì. Ó âèòêàõ êîòóøêè

áóäå ñòðóì îäíîãî íàïðÿìêó, òîìó âèòêè ïðèòÿãíóòüñÿ, ïðóæèíà ñòèñíåòüñÿ, öâÿõ ï³äí³ìåòüñÿ, êîëî ðîç³ìêíåòüñÿ, ïðóæèíà ðîçòÿãíåòüñÿ ³ öâÿõ çàíóðèòüñÿ â ðîç÷èí ñîë³. Òàêèì ÷èíîì, ï³ñëÿ çàìèêàííÿ êëþ÷à öâÿõ áóäå êîëèâàòèñÿ.

Âïðàâà ¹ 26

1. Ó ìàãí³òîåëåêòðè÷íèõ âèì³ðþâàëüíèõ ïðèëàäàõ ðàìêà, à ðàçîì ç íåþ ³

ñòð³ëêà ìîæóòü îáåðòàòèñÿ ÿê çà ÷àñîâîþ ñòð³ëêîþ, òàê ³ ïðîòè íå¿. Çà â³äñóòíîñò³ ñòðóìó ñòð³ëêà âñòàíîâëþºòüñÿ íà «0». Ïðè ïðàâèëüíîìó ï³äêëþ÷åíí³ ñòð³ëêà â³äõèëÿºòüñÿ ïðàâîðó÷ äî ïîòð³áíî¿ ïîä³ëêè, ïðè íåïðàâèëüíîìó – ë³âîðó÷, äå øêàëè íåìàº ³ ñòð³ëêà ìîæå ïîãíóòèñÿ. Â åëåêòðîìàãí³òíèõ âèì³ðþâàëüíèõ ïðèëàäàõ ïðè áóäü-ÿêîìó íàïðÿì³ ñòðóìó îñåðäÿ çàâæäè âòÿãóºòüñÿ â êîòóøêó ³ ïîâåðòàº ñòð³ëêó ïðàâîðó÷.

18

2. Àìïåðìåòð âìèêàþòü ó êîëî ïîñë³äîâíî, éîãî îï³ð ìàëèé ³ íå âïëèâàº íà

ñèëó ñòðóìó, ùî âèì³ðþºòüñÿ: ;U

IR

= 1 ;A

UI

R R=

+ ;AR R I1 ≈ I.

3. Âîëüòìåòð ìàº âåëèêèé îï³ð, ùîá ïðè ïàðàëåëüíîìó ç’ºäíàíí³ ñèëà ñòðóìó â êîë³ íå çìåíøèëàñü. Ïðè ïîñë³äîâíîìó ç’ºäíàíí³ âîëüòìåòðà:

;U

IR

= 1 ;V

UI

R R=

+ ;VR R 1 ;

V

UI

R≈ 1 .I I

4. Ðàìêà ç³ ñòðóìîì ïîâåðòàºòüñÿ â ìàãí³òíîìó ïîë³ ïîñò³éíîãî ìàãí³òó. Ðàìêà ³ ñòð³ëêà æîðñòêî ïðèêð³ïëåí³ äî îñ³. Ïîâîðîò ðàìêè çàëåæèòü â³ä ñèëè ³ íàïðÿìó ñòðóìó.

Âïðàâà ¹ 27

1. ²íäóêö³éíèé ñòðóì ó êîòóøö³ íå âèíèêàº, òîìó ùî ìàãí³òíå ïîëå, ùî ¿¿

ïðîíèçóº, íå çì³íþºòüñÿ. 2. ßêùî ó âíóòð³øí³é êîòóøö³ ñòðóì áóäå çì³íþâàòèñÿ. *3. Ïðè ïåðåì³ùåíí³ ìàãí³òà â³äíîñíî ñóö³ëüíîãî ê³ëüöÿ, â ê³ëüö³ âèíèêàº

³íäóêö³éíèé ñòðóì. ßêùî ìàãí³ò íàáëèæàºòüñÿ, âèíèêàº òàêèé ñòðóì, ÿêèé çìåíøóº çì³íó ìàãí³òíîãî ïîëÿ êð³çü ê³ëüöå, òîáòî â³äøòîâõóº ìàãí³ò. ßêùî ìàãí³ò â³äñóâàºòüñÿ, âèíèêàº ñòðóì ïðîòèëåæíîãî íàïðÿìêó, ùîá ïðèòÿãíóòè ìàãí³ò. Ó ðîçð³çàíîìó ê³ëüö³ ñòðóì íå âèíèêàº, âîíî íå âçàºìîä³º ç ìàãí³òîì.

Âïðàâà ¹ 28

1. Nå = Nð = 5. 2. Z = Np = 31 – ãàë³é.

3. N4018 pAr N 18;→ = n = 40 — 18 = 22.

4. 20Ca — Np = Ne = 20; 29Cu — Ne = 29; 32Ge — Ne = 32; 51Sb — Ne = 51;

15P — Ne = 15. Max Ne — y51Sb.

5. Ê³ëüê³ñòþ íåéòðîí³â: 23892U 238 92 146;nN− = − =

23592U 235 92 143.nN− = − =

Âïðàâà ¹ 29

1. Z = 88 — 2 = 86; A = 226 — 4 = 222; 226 4 A88 2 ZRa He X;

α→ + 222 222

86 86X R= n.

.

..

2. Z = 91 + 1 = 92; A = 234; 234 0 A91 1 ZPa e X;

β

−→ + 234 23492 92X U=

3. 238 4 234 0 234 0 23492 2 90 1 92 1 92U He Th e Pa e U.

β βα

− −→ + → + → +

4. 0,69

;N

AT

= NU = NRa = NRn; TU TRa TRn; AU ARa ARn.

Àêòèâí³ñòü Ðàäîíó íàéá³ëüøà. 6. Äàíî: Ðîçâ’ÿçàííÿ:

PU – 239 ν = 0,05 ìîëü λ = 9 ⋅ 10—13 ñ—1

A = λN; N = νNA; A = λνNA; [A] = ñ—1 ⋅ ìîëü ⋅ ìîëü—1 = ñ—1; A = 9 ⋅ 10—13 ⋅ 5 ⋅ 10—2 ⋅ 6,02 ⋅ 10—23 =

19

NA = 6,02 ⋅ 1023 ìîëü—1 A – ?

= 2,7 ⋅ 1010 ñ—1 = 2,7 ⋅ 1010 (Áê). Â³äïîâ³äü: A = 2,7 ⋅ 1010 Áê.


m = 0,2 ã λ = 3,14 ⋅ 10—17 ñ—1 NA = 6,02 ⋅ 1023 ìîëü—1 M = 235 ã/ìîëü A – ?

A = λN; ;AmNN

M= ;AmN

AM

λ=

1ã ìîëü[ ] ñ ;

ìîëü ñ ãA −⋅= =

⋅ ⋅

17 2343,14 10 0,2 6,02 10

1,6 10235

A−

−⋅ ⋅ ⋅ ⋅= = ⋅ ñ—1 =

= 1,6 ⋅ 104 (Áê). Â³äïîâ³äü: A = 1,6 ⋅ 104 Áê.

Âïðàâà ¹ 30

1. Äàíî: Ðîçâ’ÿçàííÿ: PD = 2 ⋅ 10—9 Ãð/ñ t = 1 ãîä = 3600 ñ D – ?

D = PD ⋅ t = 2 ⋅ 10—9 ⋅ 3600 = 7,2 ⋅ 10—6 (Ãð) = = 7,2 (ìêÃð). Â³äïîâ³äü: D = 7,1 ìêÃð.


N = 108 m = 1 ã = 10—3 êã Eα = 8,3 ⋅ 10—13 Äæ k = 20 H – ?

H = kD; ;W

Dm

= w = NEα; ;kNE

Hm

α=

Äæ[ ] Çâ;

êãH = =

8 13

3

20 10 8,3 101,66

10H

−

−

⋅ ⋅ ⋅= = (Çâ).

Â³äïîâ³äü: H = 1,66 Çâ. 3. Äàíî: Ðîçâ’ÿçàííÿ:

t = 1 ãîä = 3600 ñ PD = 25 ⋅ 10—9 Ãð/ñ k = 1 D – ? H – ?

D = PD ⋅ t; Ãð

[ ] ñ = Ãð;ñ

D = ⋅ H = kD;

[H] = Çâ; D = 25 ⋅ 10—9 ⋅ 3,6 ⋅ 103 = = 9 ⋅ 10—5 Ãð = 90 ìêÃð; H = 90 (ìêÇâ). Â³äïîâ³äü: D = 90 ìêÃð; H = 90 ìêÇâ.

Çàâäàííÿ äëÿ ñàìîïåðåâ³ðêè

8. PD = 25 ìêÐ/ãîä; (ìêÐ/ãîä) ⋅ 24 ãîä = 900 ìêÐ. 25DD P t= =

9. N = 7,2 ⋅ 1010 ãîä—1 = 10

77,2 102 10

3600

⋅ = ⋅ ñ—1; A = 2 ⋅ 107 Áê.

10. H = 0,01 ìêÇâ; t = 4 ãîä; 0,01 ìêÇâ

0,00254 ãîä

HP

t= = = ìêÇâ/ãîä.

11. 237 Z = 93 — 2 = 91; A = 237 — 4 = 233; A 493 p Z 2N X H→ + e; a.

i.

233 23391 91X P=

12. 210 Z = 82 + 1 = 83; A = 210; 210 A 082 Z 1Pb X e;−= + 210

83 83X B=

20

13. P = 7 ìêÃð/ãîä; t = 200 ⋅ 6 = 1200 ãîä; D = Pt = 7 ⋅ 1200 = 8400 (ìêÃð) = 8,4 ìÃð; D + Dô = 8,4 + 2 = 10,4 (ìÃð); D + Dô < 50 ìÃð – ïðàöþâàòè áåçïå÷íî.

14. N0 = 2 ⋅ 10—10 ìîëü; NA = 6,02 ⋅ 1023 ìîëü—1; λ = 1,37 ⋅ 10—11 ñ—1; N = N0 ⋅ NA ⋅ λ = 2 ⋅ 10—10 ⋅ 6,02 ⋅ 1023 ⋅ 1,37 ⋅ 10—11 = 1649 (ñ—1).

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