kiruchina 9 klass fizika by zimzone1

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; Ne′ = 12 − 2 = 10. 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 Q 1019 N= = = 6, 25 ⋅ 1018. |e| = 1,6 ⋅ 10—19 Êë e 1, 6 N–? Â³äïîâ³äü: N = 6,25 ⋅ 1018 åëåìåíòàðíèõ çàðÿä³â. 3. Äàíî: m = 0,3 ìã = 0,3 ⋅ 10— 6 êã g = 9,8 Í/êã F–?

Ðîçâ’ÿçàííÿ: F = mg = 0,3 ⋅ 10—6 ⋅ 9,8 ≅ 3 ⋅ 10—6 (Í). êã ⋅ Í [F ] = = Í. êã 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.

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

q1′ – ? q2′ – ?

Ðîçâ’ÿçàííÿ: q1′ = q2′ ; q1′ + q2′ = q1 + q2 ;

q1′ = q2′ =

q1 + q2 3 ⋅ 10 −9 − 9 ⋅ 10 −9 = = −3 ⋅ 10 −9 (Êë). 2 2

Â³äïîâ³äü: q1′ = q2′ = −3 ⋅ 10 −9 Êë. 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 ïåðåì³ùóâàòèñÿ â³ä ã³ëüçè äî ïàëè÷êè. § 4. Çàêîí Êóëîíà 1. Äàíî: q1 = q2 1 ⋅ 10—4 Êë r=1ì k = 9 ⋅ 109 Íì2/Êë2 F–?

2. Äàíî:

q1′ = 2q1 q2′ = 2q2 r′ = 4r F′ –? F 3. Äàíî: F′ = 9F

Ðîçâ’ÿçàííÿ: qq F = k 1 2 2 = 9 ⋅ 109 ⋅ 10 −4 ⋅ 10 −4 = 90 (Í); r

Í ⋅ ì2 ⋅ Êë ⋅ Êë = Í. Êë2 ⋅ ì2 Â³äïîâ³äü: F = 90 Í. [F ] =

Ðîçâ’ÿçàííÿ: qq F = k 1 22 ; r 4q q q1′ q2′ qq F = k 1 22 = k 1 22 = . r ′2 16r 4r 4 Â³äïîâ³äü: ñèëà çìåíøèòüñÿ â 4 ðàçè. F′ = k

q1 = q1′

Ðîçâ’ÿçàííÿ: qq F = k 1 22 ; r

q2 = q2′

F′ = k

r′ –? r

q1′ q2′ q q F′ r2 = k 1 22 ; = 2 = 9; r ′2 r′ F r′

⎛r⎞ ⎜⎝ r ′ ⎟⎠ = 9;

r r′ 1 = 3; = . r′ r 3

Â³äïîâ³äü: â³äñòàíü çìåíøèëàñü ó 3 ðàçè. 4. Äàíî: q1 = q2 N = 1011 r = 10 ñì = 0,1 ì F–?

5. Äàíî: Ðîçâ’ÿçàííÿ: |q1| = 5|q2|

Ðîçâ’ÿçàííÿ: q1q2 F = k 2 ; q1 = q2 = Nå; r

k ⋅ (Ne)2 9 ⋅ 109 ⋅ (1, 6 ⋅ 10 −19 ⋅ 1011 )2 = ≅ 23 ⋅ 10 −5 r2 0,12 (Í) = 2,3 ⋅ 10—4 (Í). Â³äïîâ³äü: F = 2,3 ⋅ 10—4 Í. F=

1) Êóëüêè çàðÿäæåí³ îäíîéìåííî:

q1′ = q2′ = q ′

q1 + q2 = q1′ + q2′ ;

F′ F ′′ –? –? F F

F=k

5q2

2q′;

q′

3q2;

q1q2 q ⋅ 5q 5kq = k 2 2 2 = 22 ; r2 r r

q1′ q2′ (3q2 )2 9kq2 F′ 9 =k = 2 ; = = 1, 8; F′ = 1,8F. r r2 r2 F 5 2) Êóëüêè çàðÿäæåí³ ð³çíîéìåííî: F′ = k

q1 + q2 = q1′ + q2′ ; 5q2 — q2 = 2q′; 4q2 = 2q′; q′ = 2q2; F = k

F ′′ =

q1q2 5kq22 = 2 ; r2 r

k(2q2 )2 4kq22 1 F F ′′ 4 = 2 ; = = 1, 25. = = 0, 8; F″ = 0,8F; r2 r F ′′ 0, 8 F 5

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» 11. Äàíî: F1 = 16 F2

r1 –? r2

12. Äàíî: q1′ = 3 q1

Ðîçâ’ÿçàííÿ: F1 = k

F2 = k

q1q2 ; r22

F1 ⎛ r2 ⎞ = = 16; F2 ⎜⎝ r1 ⎟⎠

r2 r 1 = 4; 1 = . r1 r2 4 Â³äïîâ³äü: â³äñòàíü çá³ëüøèëàñü âó4 ðàçè. Ðîçâ’ÿçàííÿ: q ⋅q F=k 1 2 2 ; r

q2′ = 3 q2 F′ –? F

q1q2 ; r12

F′ = k

q1′ ⋅ q2′ r2

3 ⋅ 3 q1 ⋅ q2 q ⋅q = 9k 1 2 2 = 9 F; r2 r

F′ = 9. F Â³äïîâ³äü: ñèëà âçàºìîä³¿ çá³ëüøèòüñÿ

ó 9 ðàç³â. 13. Äàíî: q1 = 2 ⋅ 10—5 Êë r = 6 ñì = 0,6 ì F = 0,1 Í q2 – ?

Ðîçâ’ÿçàííÿ: q1q2 Í ⋅ ì2 Fr 2 = Êë; F = k 2 ; q2 = ; [q2 ] = kq1 r Í ⋅ ì2 ⋅ Êë Êë2

0,1 ⋅ 3, 6 ⋅ 10 −3 = 2 ⋅ 10 −9 (Êë). 9 ⋅ 109 ⋅ 2 ⋅ 10 −5 Â³äïîâ³äü: q2 = 2 ⋅ 10—9 Êë. q2 =

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

[q2 ] =

Ðîçâ’ÿçàííÿ: N=

q2 qq Fr 2 ; F = k 1 2 2 ; q2 = ; kq1 e r

0, 9 ⋅ 64 ⋅ 10 −4 Í ⋅ ì2 = Êë; q2 = = −1, 6 ⋅ 10 −7 Êë; Í ⋅ ì2 9 ⋅ 109 ⋅ 4 ⋅ 10 −6 ⋅ Êë Êë2

−1, 6 ⋅ 10 −7 = 1012. −1, 6 ⋅ 10 −19 Â³äïîâ³äü: 1012 åëåêòðîí³â. N=

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

q1′ – ? q2′ – ? q3′ – ? F′ – ?

Ðîçâ’ÿçàííÿ: q1 + q2 + q3 = q1′ + q2′ + q3′ ;

q′ =

q1 + q2 + q3 1, 8 ⋅ 10 = 3

−8

q1′ = q2′ = q3′ = q ′;

− 0, 3 ⋅ 10 3

−8

= 0,5 ⋅ 10 −8 (Êë);

q ′2 9 ⋅ 109 ⋅ 0, 25 ⋅ 10 −16 = = 9 ⋅ 10 −5 (Í) = r2 25 ⋅ 10 −46 = 90 (ìêÍ). Â³äïîâ³äü: q′ = 0,5 ⋅ 10—8 Êë; F′ = 90 ìêÍ. F′ = k

Ðîçä³ë 2. Åëåêòðè÷íèé ñòðóì § 8. Åëåêòðè÷íå êîëî òà éîãî åëåìåíòè Âïðàâà ¹ 8 1.

§ 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: I = 200 ìÀ = 0,2 À q = 24 Êë t–?

4. Äàíî: I=3À t = 15 õâ = 900 ñ Q–?

Ðîçâ’ÿçàííÿ: Êë À ⋅ ñ q q = = ñ; I = ; t = ; [t] = À À t I 24 t= = 120 ñ = 2 (õâ.). 0,2 Â³äïîâ³äü: t = 2 õâ. Ðîçâ’ÿçàííÿ: Q I = ; Q = I ⋅ t; [Q] = À ⋅ ñ = Êë; Q = t = 3 ⋅ 900 = 2700 (Êë).

Â³äïîâ³äü: Q = 2700 Êë. 5. Äàíî: I = 0,2 À t = 10 õâ = 600 ñ Q–?

Ðîçâ’ÿçàííÿ: Q I = ; Q = I ⋅ t; [Q] = À ⋅ ñ = Êë; t Q = 0,2 ⋅ 600 = 120 Êë. Â³äïîâ³äü: Q = 120 Êë.

6. Äàíî: t = 10 ñ N = 2 ⋅ 1020 I–?

Ðîçâ’ÿçàííÿ: Q I = ; Q = N|e|; t

Ne ; t

[I ] =

Êë = À; ñ

2 ⋅ 1020 ⋅ 1, 6 ⋅ 10 −19 = 3,2 (À). 10 Â³äïîâ³äü: I = 3,2 À. I=

§ 10. Åëåêòðè÷íà íàïðóãà, îäèíèöÿ íàïðóãè, âîëüòìåòð Âïðàâà ¹ 10 10 − 0 = 1 (Â); U = 4 Â; 10 5−0 á) CV = = 0,5 (Â); U = 6 Â; 10 5−0 â) CV = = 1 (Â); U = 8 Â. 5

1. à) CV =

3. Äàíî: q = 3 Êë A = 0,12 êÄæ U–?

Ðîçâ’ÿçàííÿ: A 120 Äæ A = U ⋅ q; U = = = 40; [U ] = = Â. Êë 3 q Â³äïîâ³äü: U = 40 Â.

4. Äàíî: q = 4 Êë U=5Â A–? 5. Äàíî: q = 60 Êë m = 200 ã = 0,2 êã h = 360 ì U–?

Ðîçâ’ÿçàííÿ: A = U ⋅ q; [A] = Â ⋅ Êë = Äæ; F = 12 ⋅ 4 = 48 Äæ. Â³äïîâ³äü: À = 48 Äæ. Ðîçâ’ÿçàííÿ: A1 = q ⋅ U; A2 = mgh; A1 = A2; q ⋅ U = mgh; Í ⋅ì êã ⋅ mgh Í ⋅ ì Äæ êã = Â; U= ; [U ] = = = q Êë Êë Êë U=

0, 2 ⋅ 10 ⋅ 360 = 12 Â. 60

Â³äïîâ³äü: U = 12 Â. § 11. Åëåêòðè÷íèé îï³ð. Çàêîí Îìà Âïðàâà ¹ 11 U U ; R = ; I R = 3 Îì; II R = 3,3 Îì; III R = 5 Îì; IV R = 10 Îì. R I 2. Äàíî: Ðîçâ’ÿçàííÿ: I = 1,5 À U = I ⋅ R = 1,5 ⋅ 150 = 225 (Â). R = 150 Îì Â³äïîâ³äü: U = 225 Â. U–?

1. I =

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

4. Äàíî: U = 120 Â I = 15 ìÀ = 15 ⋅ 10—3 À R–? 5. R = 2 Îì; I =

U (Â) I (À)

0 0

Ðîçâ’ÿçàííÿ: 12 U R= = = 20 0, 6 I

(Îì);

U1 U 6 20 = = 0, 3 (À); I2 = 2 = = 1 (À); R 20 R 20 U 1 I3 = 3 = = 0, 05 (À). R 20 Â³äïîâ³äü: 0,3 À; 1 À; 0,05 À. I1 =

Ðîçâ’ÿçàííÿ: U 120 U I= ; R= = = 8000 (Îì) = 8 (êÎì). I 15 ⋅ 10 −3 R Â³äïîâ³äü: R = 8 êÎì.

U U = = 0,5U; R 2 2 4… 1 2…

6. Äàíî: U = 12 Â t = 5 õâ = 300 ñ q = 60 Êë R–?

7. Äàíî: I = 1,2 À U = 18 Â R–?

U I= ; R

Ðîçâ’ÿçàííÿ: Ut U U q ; I= ; R= ; I= ; R= I t R q Â ⋅ Êë 12 ⋅ 300 = Îì; R = = 60 (Îì). ñ 60 Â³äïîâ³äü: R = 60 Îì. [R] =

Ðîçâ’ÿçàííÿ: U 18 U = = 15 (Îì). I= ; R= R I 1,2 Â³äïîâ³äü: R = 15 Îì.

Ðîçâ’ÿçàííÿ: 8. Äàíî: U=6Â 6 U I 4 = = 4 (À); CA = CA = ; I= = 0, 25 (À). R = 1,5 Îì 16 N R 1,5 N = 16 Â³äïîâ³äü: CA = 0,25 À. CA – ? l 9. R = ρ . Îï³ð ïðîâ³äíèêà çàëåæèòü â³ä éîãî ðîçì³ðó ³ ìàòåð³àëó. S § 12. Ïèòîìèé îï³ð ðå÷îâèíè Âïðàâà ¹ 12 1. Äàíî: Rç = Rì = Rñ S ç = Sì = Sñ ρñ > ρç > ρì lç, lì, lñ – ?

Ðîçâ’ÿçàííÿ: l R = ρ ; S = const; ρñ ⋅ lñ = ρç ⋅ lç = ρì ⋅ lì; S ρñ > ρç > ρì; lñ > lç > lì. Â³äïîâ³äü: 3 – ñâèíåöü, 2 – çàë³çî, 1 – ì³äü.

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

4. Äàíî: R = 25 Îì l1 = 0,5l S1 = 2S R1 – ?

Ðîçâ’ÿçàííÿ: R=ρ

Îì ⋅ ìì2 ì l ⋅ = Îì; ; [ R] = ì ìì2 S

0, 017 ⋅ 103 = 0,25 (Îì). 68 Â³äïîâ³äü: R = 0,25 Îì. R=

Ðîçâ’ÿçàííÿ: ρl1 0,5ρl ρl ρl = = 0,25 = 0,25R; R1 = 0,25 R. R = ; R1 = S S1 S 2S Â³äïîâ³äü: îï³ð çìåíøèâñÿ ó 4 ðàçè.

U 4,2 = = 3 (Îì). I 1, 4 Ïðè ïåðåñóâàíí³ ïîâçóíêà ðåîñòàòà âïðàâî éîãî îï³ð çìåíøèòüñÿ, íàïðóãà íå çì³íèòüñÿ, ñòðóì çá³ëüøèòüñÿ.

5. I = 1,4 À; U = 4,2 Â; R =

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

Ðîçâ’ÿçàííÿ: RS US ρl U ; R= ; l= ; R= ; l= S I Iρ ρ Â ⋅ ìì2 Îì ⋅ ìì2 ⋅ ì = = ì; Îì ⋅ ìì2 Îì ⋅ ìì2 À⋅ ì 4, 4 ⋅ 0,2 l= = 2 (ì). 0, 4 ⋅ 1,1 [l] =

Â³äïîâ³äü: l = 2 ì. 7. Äàíî: I = 15 À l = 10 ì U = 0,85 Â ρ = 0,017 (Îì⋅ìì2)/ì d–?

Ðîçâ’ÿçàííÿ:

πd2 S= ; 4

d=2

S ; π

d=2

ρlI ; Uπ

[d] =

Îì ⋅ ìì2 ⋅ À ⋅ ì = ì⋅Â

ρl ; S

ρl ρlI ; = R U

Îì ⋅ ìì2 = ìì; Îì

0, 017 ⋅ 10 ⋅ 15 ≅ 2 (ìì). 0, 85 ⋅ 3,14 Â³äïîâ³äü: d = 2 ìì. d=2

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

Ðîçâ’ÿçàííÿ: m = η ⋅ V = η ⋅ l ⋅ S; R =

ρl ρl ρlI ; S= ; = S R U

Îì ⋅ ìì2 ⋅ ì ⋅ À Îì ⋅ ìì2 = = ìì2 ; ì⋅Â Îì 0, 028 ⋅ 100 ⋅ 15 = 42 ìì2 = 42 ⋅ 10—6 ì2. S= 1 êã [m] = 3 ⋅ ì ⋅ ì2 = êã; ì m = 2700 ⋅ 100 ⋅ 42 ⋅ 10—6 = 11,34 (êã). Â³äïîâ³äü: m = 11,34 êã. [S] =

Âïðàâà ¹ 13 1. Äàíî: R = 65 Îì R1 = R2 = 15 Îì R3 – ?

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

2. Äàíî: R1 = 15 Îì R2 = 10 Îì U = 100 Â U1 – ?

Ðîçâ’ÿçàííÿ: UR1 U ; U1 = ; U1 = I⋅ R1; I = R1 + R2 R1 + R2

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

Â ⋅ Îì 100 ⋅ 15 = Â; U1 = = 60 (Â). Îì + Îì 25 Â³äïîâ³äü: íàïðóãà ì³æ êëåìàìè k1 ³ k2 60 Â. [U1 ] =

Ðîçâ’ÿçàííÿ: U 220 I= = = 0, 2 (À) – òàêèé ñòðóì ïîòå÷å êð³çü R 1100 ïîñë³äîâíî ç’ºäíàí³ ëàìïè. I < I1, òîìó ëàìïó äëÿ ë³õòàðèêà òàê ìîæíà âìèêàòè. Â³äïîâ³äü: ìîæíà.

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

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

Ðîçâ’ÿçàííÿ: R = R1 + R2; R2 = R — R1; I =

U U ; R= ; R I

72 U − 650 = 250 (Îì). − R1; R2 = I 0, 08 Â³äïîâ³äü: 250 Îì. R2 =

Ðîçâ’ÿçàííÿ: U2 1, 6 I = I2 = = = 0, 2 (À); U = I ⋅ R; R = R1 + R2 + R3; 8 R2 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

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

3. Äàíî: U = 120 Â R1 = 200 Îì R2 = 300 Îì I – ? I1 – ? I2 –?

Ðîçâ’ÿçàííÿ: 1 1 1 1 1 U = I ⋅ R; = + = + = 0, 0167; R R1 R2 100 150

1 ≅ 60 (Îì); U = 2,4 ⋅ 60 ≅ 144 (Â). 0, 0167 Â³äïîâ³äü: U = 144 Â. R=

Ðîçâ’ÿçàííÿ: U I= ; R 1 1 1 1 1 = + = + = 0, 005 + 0, 0033 = 0, 0083; R R1 R2 200 300

1 120 ≅ 120 (Îì); I = = 1 (À); 120 0, 0083

U1 = U2 = U; I1 =

U1 U 120 = = = 0, 6 (À); R1 R1 200

U2 U 120 = = = 0, 4 (À). R2 R2 300 Â³äïîâ³äü: I = 1 À; I1 = 0,6 À; I2 = 0,4 À. I2 =

4. Äàíî: ρç > ρì > ρñ Iç – ? Iì – ? Iñ – ?

Ðîçâ’ÿçàííÿ: U U U ; Iì = ; I = ; U1 = U2 = U3 = U; Iз = R Rз Rì U ρl ; R = ; Rç > Rì > Rñ; Iç > Iì > Iñ. S Rñ Â³äïîâ³äü: ó ñð³áíîìó äðîò³ ñèëà ñòðóìó á³ëüøà. Iñ =

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

åêâ³âàëåíòà åëåêòðè÷íà ñõåìà

R–?I–?

1 1 1 1 1 = + = + = 0, 83; R6 = 1,2 (Îì); R6 R1 R2 2 3 1 1 1 1 1 1 = + = + = ; R7 = 2 (Îì); R7 R3 R4 4 4 2 T = R5 + R6 + R7 = 0,8 + 1,2 + 2 = 4 (Îì); U 4 I= = = 1 (À). R 4 Â³äïîâ³äü: R = 4 Îì; I = 1 À. 6. Äàíî: R1 = 3 Îì R2 = 2 Îì R3 = 8 Îì I3 = 0,1 À U–?

Ðîçâ’ÿçàííÿ: U3 = I3 ⋅ R3 = 0,1 ⋅ 8 = 0,8 (Â); U3 = U2 = 0,8 Â; U 0, 8 I2 = 2 = = 0, 4 (À); I1 = I2 + I3 = 0,4 + 0,1 = 0,5 (À); R2 2 U1 = I1 ⋅ R1 = 0,5 ⋅ 3 = 1,5 (Â); U = U1 + U2 = 1,5 + 0,8 = = 2,3 (Â). Â³äïîâ³äü: U = 2,3 Â. Âïðàâà ¹ 15

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

Ðîçâ’ÿçàííÿ: 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.

2. A = U ⋅ I ⋅ t; [A] = Äæ; [U ⋅ I ⋅ t] = Â ⋅ À ⋅ ñ. 3. Äàíî: Ðîçâ’ÿçàííÿ: I = 0,8 À A = U ⋅ I ⋅ t = 3,4 ⋅ 0,8 ⋅ 900 = 2448 (Äæ) = U = 3,4 Â = 2,448 (êÄæ). t = 15 õâ = 900 ñ Â³äïîâ³äü: A = 2,448 êÄæ. A–? 4. Äàíî: Ðîçâ’ÿçàííÿ: R1 = 10 Îì R2 = 25 Îì U = 100 Â t = 5 õâ = 300 ñ A1 – ? A2 – ? A3 – ? A4 – ?

à) Ïàðàëåëüíå ç’ºäíàííÿ ïðîâ³äíèê³â: U2 A = UIt = t; R A1 =

U2 1002 t= ⋅ 300 = 300 000 (Äæ) = 300 (êÄæ); R1 10

A2 =

U2 1002 t= ⋅ 300 = 120 000 (Äæ) = 120 (êÄæ). R2 25

á) Ïîñë³äîâíå ç’ºäíàííÿ ïðîâ³äíèê³â: U 100 R = R1 + R2 = 10 + 25 = 35 Îì; I = = = 2, 86 (À); A = UIt = I2 Rt; R 35 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. 5. Äàíî: P1 = 90 Âò P2 = 40 Âò U = 220 Â I1 – ? I2 – ? R1 – ? R2 – ?

Ðîçâ’ÿçàííÿ:

P = UI =

U2 ; R

P1 =

U2 ; R1

P1 =

U 2 2202 = = 538 R1 90

(Îì);

P2 =

220 U U 2 2202 = = 1210 (Îì); I1 = = = 0, 41 (À); R2 40 R1 538

I2 =

220 U = = 0,18 (À). R2 1210

Â³äïîâ³äü: I1 = 0,41 À; I2 = 0,18 À; R1 = 538 Îì; R2 = 1210 Îì. 6. Äàíî: m = 1 ò = 103 êã h = 19 ì t = 50 ñ η = 80 % U = 380 Â I–?

Ðîçâ’ÿçàííÿ: Aêîð. mgh ; Aêîð. = mgh; Aïîâíà = UIt; η = ; η= UIt Aïîâí. I=

103 ⋅ 10 ⋅ 19 mgh = = 12,5 (À); Utη 380 ⋅ 50 ⋅ 0, 8

êã ⋅ ì ⋅ Í Í⋅ì Äæ êã ⋅ = = = À. Äæ êã ⋅ Â ⋅ ñ Äæ ñ ⋅ñ Êë Â³äïîâ³äü: I = 12,5 À. [I ] =

*7. Äàíî: Ðîçâ’ÿçàííÿ: U = 127 Â P 50 P = UI; I = = = 0,39 (À); P = 50 Âò U 127 U1 = 220 Â U1 — U = IR; R–? U − U 220 − 127 R= 1 = = 238 0,39 I (Îì). Â³äïîâ³äü: R = 238 Îì. 8*. Äàíî: R1 = R2 = R Pïîñë. – ? Pïàð. – ?

Ðîçâ’ÿçàííÿ:

U2 U2 P = UI = ; Pïîñë. = ; Rïîñë. = R1 + R2 = 2R; R Rïîñë. Rïîñë. = Pïàð. =

U2 ; 2R

Pïàð. =

U2 ; Rïàð.

1 1 1 2 = + = ; Rïàð. R1 R2 R

Rïàð. 2U 2 ; = 4. R Pïîñë.

Â³äïîâ³äü:

Rïàð Pïîñ

= 4.

Âïðàâà ¹ 16 1. Q = I2Rt; Râîëîñêà Rïðîâîä³â; Qâîëîñêà Qïðîâîä³â. 2. Äàíî: R = 30 Îì I=4À t = 10 õâ = 600 ñ Q–? 3. Äàíî: R1 = 10 Îì R2 = 20 Îì U = 100 Â t=5ñ Q1 – ? Q2 – ?

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

U2 U2 1002 Q= t; Q1 = t= ⋅ 5 = 5000 (Äæ) = R R1 10 = 5 (êÄæ); Q2 =

U2 1002 t= ⋅ 5 = 2500 (Äæ) = R2 20

= 2,5 (êÄæ). Â³äïîâ³äü: Q1 = 5 êÄæ; Q2 = 2,5 êÄæ. 4. Äàíî: t1° = 20 °Ñ t2° = 100 °Ñ V = 1,5 ë P = 600 Âò η = 80 % t–?

Ðîçâ’ÿçàííÿ: Qêîð = ηQïîâíà; Qïîâíà = Pt; Qêîð = cm(t2° — t1°); cm(t2° — t1°) = ηPt; cm(t2 ° − t1 °) 4200 ⋅ 1,5 ⋅ (100 − 20) t= = = 1050 (ñ). 0, 8 ⋅ 600 ηP Â³äïîâ³äü: t = 1050 ñ.

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

Ðîçâ’ÿçàííÿ: Q = UIt; Q = cm(t2° — t1°); Q cm(t2 ° − t1 °) 4200 ⋅ 0, 2 ⋅ (100 − 14) U= = = = 120 (Â). 2 ⋅ 300 It It Â³äïîâ³äü: U = 120 Â.

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

Ðîçâ’ÿçàííÿ:

U 2t ρl 4ρl U 2t Q= ; R= ; R= = ; R S πd 2 Q πd2 R πd2U 2t 3,14 ⋅ 0, 25 ⋅ 1202 ⋅ 3600 = = = 9,2 (ì). 4ρ 4Qρ 4 ⋅ 1,1 ⋅ 106 Â³äïîâ³äü: l = 9,2 ì. l=

Âïðàâà ¹ 17 4. Äàíî: Imax = 6 À U = 220 Â Pmax – ?

Ðîçâ’ÿçàííÿ: 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 U2 ρl t; R = . ßêùî â ã³ïîòåòè÷í³é ïëèòö³ Q2 = Q ïðè íàãð³âàííÿì. Q = R S 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

m êã ; [k] = . q Êë 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.

1. m = kIt = kq; k =

4. Äàíî: Ðîçâ’ÿçàííÿ: m = 25 ã I = 0,5 À k = 1,2 ìã/Êë t–?

m 25 ⋅ 103 = = 44, 6 ⋅ 103 (ñ) = kI 1,12 ⋅ 0,5 = 44 600 ñ = 744 õâ = 12,4 (ãîä). Â³äïîâ³äü: t = 12,4 ãîä. m = kIt; t =

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

Ðîçâ’ÿçàííÿ: kUt 1,12 ⋅ 2 ⋅ 7200 m = kIt = = = 40 320 0, 4 R = 40,32 (ã). Â³äïîâ³äü: m = 40,32 ã.

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

(ìã) =

Ðîçâ’ÿçàííÿ:

3000 m = = 0, 9 (À); kt 1,12 ⋅ 3000 P = UI = I2R = 0,92 ⋅ 0,4 ≅ 0,32 (Âò). Â³äïîâ³äü: P = 0,32 Âò.

m = kIt; I =

Âïðàâà ¹ 20 1. Äàíî: Ðîçâ’ÿçàííÿ: 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–?

2. Äàíî: 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–? 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; t = t=

m ; m = ρV = ρSd; kI

ρSd 10,5 ⋅ 103 ⋅ 0, 03 ⋅ 8 ⋅ 10 −6 = = kI 1,12 ⋅ 10 −6 ⋅ 1, 4

= 1, 6 ⋅ 103 (ñ) = 26,8 õâ; A = UIt = 11 ⋅ 1,4 ⋅ 1,6 ⋅ 103 = = 24,6 ⋅ 103 (Äæ) = 24,6 (êÄæ). Â³äïîâ³äü: t = 26,8 õâ; A = 24,6 êÄæ. Ðîçâ’ÿçàííÿ: m = kIt; m = ρSd; m kIt 0,34 ⋅ 10 −6 ⋅ 0, 48 ⋅ 900 d= = = = ρS ρS 7,1 ⋅ 103 ⋅ 0, 01 = 2 ⋅ 10 −6 (ì) = 2 (ìêì). Â³äïîâ³äü: d = 2 ìêì.

m = kIt; t = t=

m ; m = NρSd; kI

N ρSd ; kI

12 ⋅ 10,5 ⋅ 103 ⋅ 5 ⋅ 10 −3 ⋅ 58 ⋅ 10 −6 = 1,12 ⋅ 10 −6 ⋅ 1, 8 = 18 000 (ñ) = 5 (ãîä). Â³äïîâ³äü: t = 5 ãîä. t=

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 áóäüÿêèì 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.

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.

Çà äîïîìîãîþ ïðàâèëà ë³âî¿ ðóêè âèçíà÷àºìî íàïðÿìîê ìàãí³òíîãî ïîëÿ ³ ïîëþñè ìàãí³òà.

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÷.

2. Àìïåðìåòð âìèêàþòü ó êîëî ïîñë³äîâíî, éîãî îï³ð ìàëèé ³ íå âïëèâàº íà U U ; RA R; I1 ≈ I. ñèëó ñòðóìó, ùî âèì³ðþºòüñÿ: I = ; I1 = R R + RA 3. Âîëüòìåòð ìàº âåëèêèé îï³ð, ùîá ïðè ïàðàëåëüíîìó ç’ºäíàíí³ ñèëà ñòðóìó â êîë³ íå çìåíøèëàñü. Ïðè ïîñë³äîâíîìó ç’ºäíàíí³ âîëüòìåòðà: U U U ; RV R; I1 ≈ ; I1 I. I = ; I1 = RV R + RV R 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. 4.

40 18

Ar → Np = 18; Nn = 40 — 18 = 22.

Ca — Np = Ne = 20; 29Cu — Ne = 29; 15P — Ne = 15. Max Ne — y51Sb.

5. Ê³ëüê³ñòþ íåéòðîí³â: 235 92

238 92

Ge — Ne = 32;

Sb — Ne = 51;

U − Nn = 238 − 92 = 146;

U − Nn = 235 − 92 = 143. Âïðàâà ¹ 29

1. 2. 3.

226 88 234 91 238 92

Ra → 42 He + AZ X; Z = 88 — 2 = 86; A = 226 — 4 = 222; β

Pa → α

0 −1

e + AZ X; Z = 91 + 1 = 92; A = 234;

U → 42 He +

Th → −01 e +

234 90

234 92

Pa → −01 e +

234 92

222 86

Rn.

U...

0, 69N 4. A = ; NU = NRa = NRn; TU TRa TRn; AU ARa ARn. T Àêòèâí³ñòü Ðàäîíó íàéá³ëüøà.

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

Ðîçâ’ÿçàííÿ: 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 =

NA = 6,02 ⋅ 1023 ìîëü—1 A–?

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

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

Ðîçâ’ÿçàííÿ: mN A λmN A A = λN; N = ; A= ; M M ã ⋅ ìîëü [ A] = = ñ −1 ; ìîëü ⋅ ñ ⋅ ã

3,14 ⋅ 10 −17 ⋅ 0,2 ⋅ 6, 02 ⋅ 1023 = 1, 6 ⋅ 10 −4 ñ—1 = 235 = 1,6 ⋅ 104 (Áê). Â³äïîâ³äü: A = 1,6 ⋅ 104 Áê.

1. Äàíî: PD = 2 ⋅ 10—9 Ãð/ñ t = 1 ãîä = 3600 ñ D–?

Âïðàâà ¹ 30 Ðîçâ’ÿçàííÿ: D = PD ⋅ t = 2 ⋅ 10—9 ⋅ 3600 = 7,2 ⋅ 10—6 (Ãð) = = 7,2 (ìêÃð). Â³äïîâ³äü: D = 7,1 ìêÃð.

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

Ðîçâ’ÿçàííÿ: kNEα W H = kD; D = ; w = NEα; H = ; m m Äæ [ H] = = Çâ; êã

20 ⋅ 108 ⋅ 8,3 ⋅ 10 −13 = 1, 66 (Çâ). 10 −3 Â³äïîâ³äü: H = 1,66 Çâ.

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

Ðîçâ’ÿçàííÿ: D = PD ⋅ t;

[ D] =

Ãð ⋅ ñ = Ãð; ñ

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; D = PD t = 25 (ìêÐ/ãîä) ⋅ 24 ãîä = 900 ìêÐ.

7, 2 ⋅ 1010 = 2 ⋅ 107 ñ—1; A = 2 ⋅ 107 Áê. 3600 H 0, 01 ìêÇâ 10. H = 0,01 ìêÇâ; t = 4 ãîä; P = = = 0, 0025 ìêÇâ/ãîä. 4 ãîä t 9. N = 7,2 ⋅ 1010 ãîä—1 =

11.

237 93

Np →

A Z

12.

210 82

Pb =

X+

A Z

X + 42 He; Z = 93 — 2 = 91; A = 237 — 4 = 233; 0 −1

e; Z = 82 + 1 = 83; A = 210;

210 83

233 91

Pa.

Bi.

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).