Предмет: Физика, автор: wwqp1

На рисунке показана электрическая схема, состоящая из источника постоянного напряжения U, амперметра, ключа К и трёх резисторов, имеющих сопротивления R1, R2 и R3, которые соответственно равны 67, 29 и 60 Ом.

Сначала, когда ключ был разомкнут, амперметр показывал силу тока I1 = 1 А. После замыкания ключа сила тока I2, текущего через амперметр, стала равна
А. Ответы округли до сотых!

ПОЖАЛУЙСТА ПОМОГИТЕ!!!!!!!!!!

Приложения:

Ответы

Автор ответа: AlexUstasu

Ответ:

Показания амперметра равны 1.97 (с округлением до сотых)

Объяснение:

После замыкания

Iобщ= I1+I23 - по закону Кирхгофа.

I1=1 А. и после замыкания не изменится.

Необходимо определить I23.

Закон Ома I=U/R

U после замыкания не изменится.

Определим U

U=I1*R1=1*67= 67 В

Определим I23

I23= U/R23= 67/(29+60)=67/69

Iобщ= 1+ 67/69= 1.97 (с округлением до сотых)

--------------------------------

Второй вариант

1. Определим U общее

2. Определим R общее

3. Вычислим I общее

Uобщее вычислили и оно равно 67 В.

Определим Rобщ

1/Rобщ = 1/R1 + 1/(R2+R3) = 1/67 + 1/69 = 136/4623

Rобщ = 4623/136

Вычислим I общее

Iобщ= 67 / 4623/136 = 67*136/4623 = 1.97 (с округлением до сотых)

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Changing a Traditional
Way of Life Until recently, most people in China were farmers. Farming was the hard. Farmers did hard traditional way of life for Chinese people. Life was physical work. Each boy assumed he would be a farmer when he grew up. And each girl assumed she would become the wife of a farmer in the community. When the
boys and girls grew up and got married, their lives were clearly defined. The man took care of the farm, and the wife took care of the home. Their aging parents lived with them because that was the tradition.
In the last 50 years, several factors have caused young adults to leave the farms. They are seeking jobs in a city. As a consequence, the traditional way of life in China is changing.
WHY YOUNG ADULTS MOVED TO CITIES
Television was one factor that drew young adults to the cities. Television showed young Chinese men and women how other people lived. They saw many ways to earn money in a city. City jobs seemed physically easier than farming. Money was another factor that drew young adults to the cities. Farming provided sufficient food to
eat. Farming did not provide sufficient money to buy computers or cell phones. The young adults wanted money to buy modern things. Money from a city job helped them buy these things. They were
also able to send money home. The money assisted their aging parents.
The economic goals of the Chinese government were another factor. Government leaders believed
that China could not define itself as a modern nation if many people were poor and lived on farms. As a result, the government created a plan. The government would assist 300 to 500 million people to move from farms to cities by 2020. Many young adults were happy to leave the farm and move to a city.
A CHANGING WAY OF LIFE
Soon the Chinese economy was growing. Factories in the cities offered low-paying jobs to the new workers. But the factory workers still earned more money than farmers earned. The products made in the factories were shipped to other countries. This brought money into the Chinese economy. As
more people moved to cities, new jobs were created. More housing was needed. Workers were
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