Hai sợi dây đồng giống nhau được uốn thành hai khung dây tròn, khung thứ nhất chỉ có một vòng, khung thứ hai có 2 vòng. Nối hai đầu mỗi khung vào hai cực của mỗi nguồn điện để dòng điện chạy trong mỗi vòng của hai khung là như nhau. Hỏi cảm ứng từ tại tâm của khung nào lớn hơn và lớn hơn bao nhiêu lần:

Chia sẻ

Một số câu hỏi khác có thể bạn quan tâm.

• Choose the best answer for the following sentence:

  He failed the exam to university last year. Since then he ______________ very hard
  the next entrance examination.
   

• Choose a word that has different stress pattern:

  education                 romantic                      conversation                      information

• Choose the best answer for the following sentence:

  I sent email to my pen pal three weeks ago but she ___________ so far.
  
  

• Choose a word that has different stress pattern:

  basketball                 diploma                 champion                  evidence

• Choose the best answer for the following sentence:

  Albert Einstein was the scientist who _____________ the theory of relativity.
  
  

• Choose the best answer for the following sentence:

  How long do you think this bad weather will __________?
  
  

• Choose the best answer for the following sentence:

  In some famine villages, the people are ___________ need of many things, especially foods and medicine.
  
  

• Find a mistake in the four underlined parts of the sentence and correct it:

  One of the major causes of road accidents is drive after drinking.

• Choose the best answer for the following sentence:

  At the age of ten he left the countryside ___________ this big city with an ambition of a young man.
   

• Choose the best answer for the following sentence:

  Tan: “How can I get to your house?”

  Hue: “Go ahead, take the first turning __________. My house is opposite to a book store”