Cho đoạn mạch RLC nối tiếp, R thay đổi được, hiệu điện thế hai đầu đoạn mạch u =60cos100πt (V). Khi R₁ = 9Ω hoặc R₂ = 16Ω thì công suất trong mạch như nhau. Hỏi với giá trị nào của R thì công suất mạch cực đại, giá trị cực đại đó?           

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Một số câu hỏi khác có thể bạn quan tâm.

• Choose the best answer for the following sentence:

  I didn’t expect _____________ the job.
   

• Choose one sentence that has the same meaning as the root one:

  They made her train eight hours a day.

• Choose the word that has the underlined part pronounced differently from the rest:

  stop                    post                    offer                    from

• Choose the word that has the underlined part pronounced differently from the rest:

  school                  stood                     good                    look

• Choose a word that has different stress pattern:

  customer                   deliver                    kilometre                    document

• Choose the best answer for the following sentence:

  David, ______________ works in the central post office, is my best friend.

• Choose the best answer for the following sentence:

  ''____________ do you go to the post office, Nam?''

  ''Twice a week

• Choose the best answer for the following sentence:

  Our office is equipped ______________ advanced technology.

• Choose the best answer for the following sentence:

  The message introduces the ______________ provided by the Nationl Post Office.

• Choose one sentence that has the same meaning as the root one:

  Mrs. Mai is our English teacher. Her daughter works in the city ’s post office.