Задача №1
Находим Rобщ.:
![\frac{1}{R}=\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}}=\frac{1}{100}+\frac{1}{300}+\frac{1}{50}=\frac{1}{30} \frac{1}{R}=\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}}=\frac{1}{100}+\frac{1}{300}+\frac{1}{50}=\frac{1}{30}](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7BR%7D%3D%5Cfrac%7B1%7D%7BR_%7B1%7D%7D%2B%5Cfrac%7B1%7D%7BR_%7B2%7D%7D%2B%5Cfrac%7B1%7D%7BR_%7B3%7D%7D%3D%5Cfrac%7B1%7D%7B100%7D%2B%5Cfrac%7B1%7D%7B300%7D%2B%5Cfrac%7B1%7D%7B50%7D%3D%5Cfrac%7B1%7D%7B30%7D)
Следовательно Rобщ.=30 (Ом)
Из закона Ома найдем напряжение
I=U/R => U=I*Rобщ.=2*30=60 (В)
Найдем токи протекающие через каждый резистор:
![I_{1}=\frac{U}{R_{1} } =\frac{60}{100}=0.6 (A) \\I_{2}=\frac{U}{R_{2} } =\frac{60}{300}=0.2 (A) \\I_{3}=\frac{U}{R_{3} } =\frac{60}{50}=1.2 (A) I_{1}=\frac{U}{R_{1} } =\frac{60}{100}=0.6 (A) \\I_{2}=\frac{U}{R_{2} } =\frac{60}{300}=0.2 (A) \\I_{3}=\frac{U}{R_{3} } =\frac{60}{50}=1.2 (A)](https://tex.z-dn.net/?f=I_%7B1%7D%3D%5Cfrac%7BU%7D%7BR_%7B1%7D%20%7D%20%3D%5Cfrac%7B60%7D%7B100%7D%3D0.6%20%28A%29%20%5C%5CI_%7B2%7D%3D%5Cfrac%7BU%7D%7BR_%7B2%7D%20%7D%20%3D%5Cfrac%7B60%7D%7B300%7D%3D0.2%20%28A%29%20%5C%5CI_%7B3%7D%3D%5Cfrac%7BU%7D%7BR_%7B3%7D%20%7D%20%3D%5Cfrac%7B60%7D%7B50%7D%3D1.2%20%28A%29)
Найдем мощность тока на каждом резисторе:
![P_{1}=U*I_{1}=60*0.6=36 (W)\\P_{2}=U*I_{2}=60*0.2=12 (W)\\P_{3}=U*I_{3}=60*1.2=72 (W) P_{1}=U*I_{1}=60*0.6=36 (W)\\P_{2}=U*I_{2}=60*0.2=12 (W)\\P_{3}=U*I_{3}=60*1.2=72 (W)](https://tex.z-dn.net/?f=P_%7B1%7D%3DU%2AI_%7B1%7D%3D60%2A0.6%3D36%20%28W%29%5C%5CP_%7B2%7D%3DU%2AI_%7B2%7D%3D60%2A0.2%3D12%20%28W%29%5C%5CP_%7B3%7D%3DU%2AI_%7B3%7D%3D60%2A1.2%3D72%20%28W%29)
Найдем работу тока за 4 мин (240с) на каждом резисторе:
![A_{1}=U*I_{1}*t=P_{1}*t=36*240=8640\\A_{2}=U*I_{2}*t=P_{2}*t=12*240=2880\\A_{3}=U*I_{3}*t=P_{3}*t=72*240=17280 A_{1}=U*I_{1}*t=P_{1}*t=36*240=8640\\A_{2}=U*I_{2}*t=P_{2}*t=12*240=2880\\A_{3}=U*I_{3}*t=P_{3}*t=72*240=17280](https://tex.z-dn.net/?f=A_%7B1%7D%3DU%2AI_%7B1%7D%2At%3DP_%7B1%7D%2At%3D36%2A240%3D8640%5C%5CA_%7B2%7D%3DU%2AI_%7B2%7D%2At%3DP_%7B2%7D%2At%3D12%2A240%3D2880%5C%5CA_%7B3%7D%3DU%2AI_%7B3%7D%2At%3DP_%7B3%7D%2At%3D72%2A240%3D17280)
Работа тока измеряется в Дж
Задача №2
Находим Rобщ.:
![\frac{1}{R} =\frac{1}{(R_{2}+R_{4} )}+\frac{1}{(R_{1}+R_{3} )}=\frac{1}{70+130}+\frac{1}{415+185}=\frac{4}{600}=\frac{1}{150} (Om) \frac{1}{R} =\frac{1}{(R_{2}+R_{4} )}+\frac{1}{(R_{1}+R_{3} )}=\frac{1}{70+130}+\frac{1}{415+185}=\frac{4}{600}=\frac{1}{150} (Om)](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7BR%7D%20%3D%5Cfrac%7B1%7D%7B%28R_%7B2%7D%2BR_%7B4%7D%20%29%7D%2B%5Cfrac%7B1%7D%7B%28R_%7B1%7D%2BR_%7B3%7D%20%29%7D%3D%5Cfrac%7B1%7D%7B70%2B130%7D%2B%5Cfrac%7B1%7D%7B415%2B185%7D%3D%5Cfrac%7B4%7D%7B600%7D%3D%5Cfrac%7B1%7D%7B150%7D%20%20%20%20%28Om%29)
Из закона Ома найдем напряжение
I=U/R => U=I*Rобщ.=3*150=450 (В)
Найдем ток на участке R2 и R4:
![I=\frac{U}{R_{2}+R_{4}}=\frac{450}{70+130}=2.25 (A) I=\frac{U}{R_{2}+R_{4}}=\frac{450}{70+130}=2.25 (A)](https://tex.z-dn.net/?f=I%3D%5Cfrac%7BU%7D%7BR_%7B2%7D%2BR_%7B4%7D%7D%3D%5Cfrac%7B450%7D%7B70%2B130%7D%3D2.25%20%28A%29)
Найдем ток на участке R1 и R3:
![I=\frac{U}{R_{1}+R_{3}}=\frac{450}{415+185}=0.75 (A) I=\frac{U}{R_{1}+R_{3}}=\frac{450}{415+185}=0.75 (A)](https://tex.z-dn.net/?f=I%3D%5Cfrac%7BU%7D%7BR_%7B1%7D%2BR_%7B3%7D%7D%3D%5Cfrac%7B450%7D%7B415%2B185%7D%3D0.75%20%28A%29)
позже напишу полный ответ, хотя ход решения уже очевиден