Một khung dây tròn gồm 24 vòng dây, mỗi vòng dây có dòng điện cường độ 0,5A chạy qua. Tính toán thấy cảm ứng từ ở tâm khung bằng 6,3. 10^-5T. Bán kính của khung dây đó là:

Chia sẻ

Một số câu hỏi khác có thể bạn quan tâm.

• Choose the best answer for the following sentence:

  _______________ the Beatles first appeared on TV.
   

• Choose a word that has different stress pattern:

  until                   unknown                  midnight                   emerge

• Choose a word that has different stress pattern:

  modern                     simple                     because                   mainly

• Choose a word that has different stress pattern:

  instrument                      composer                     arrangement                      electric

• Choose a word that has different stress pattern:

  symphony                    satisfy                      different                    dependent

• Choose the best answer for the following sentence:

  We cannot compare this kind of music ___________ another kind because each has its own features.

   

• Choose the best answer for the following sentence:

  What a ___________ piece of music she is playing!

   

• Choose the best answer for the following sentence:

  ____________ is a kind of music, emerging in the early 1900s, usually with a strong beat and simple tunes, created with electrical or electronic equip¬ment and easy to listen to and remember.

   

• Choose the best answer for the following sentence:

  _____________ is a kind of popular music developed in the 1950s which has a strong beat and is played on electrical instruments.

   

• Choose the best answer for the following sentence:

  Romantic music often ____________ the listeners’ emotion.