Đặt điện áp u = U₀cosωt (U₀ và ω không đổi) vào hai đầu đoạn mạch gồm cuộn dây không thuần cảm mắc nối tiếp với tụ điện có điện dung C (C thay đổi được). Khi C = C₀ thì cường độ dòng điện trong mạch sớm pha hơn u là φ₁ và điện áp hiệu dụng giữa hai đầu cuộn dây là 45 V. Khi C = 3C0 thì cường độ dòng điện trong mạch trễ pha hơn u là φ2 =- φ₁ và điện áp hiệu dụng giữa hai đầu cuộn dây là 135 V. Giá trị của U₀ gần giá trị nào nhất sau đây?                

Chia sẻ

Một số câu hỏi khác có thể bạn quan tâm.

• Đồ thị hàm số  có bao nhiêu điểm cực trị?        

• Đảng và Nhà nước ta có chính sách đặc xá đối với người phạm tội nhằm giáo dục, động viên, giúp đỡ người phạm tội tích cực cải tạo thể hiện tinh thần nào ?
  
• Dân số thành thị của nước Nga sống chủ yếu ở các thành phố
  

• At the beginning, everybody spoke English very quickly, and I couldn’t understand ________, but now things are easier.

• Giải phương trình .         

• Gọi là tập hợp tất cả các số tự nhiên có chữ số. Chọn ngẫu nhiên một số từ tập . Tính xác suất để chọn được số chia hết cho và chữ số hàng đơn vị là số nguyên tố.
• Kết cấu hạ tầng của sản xuất thuộc yếu tố cơ bản nào dưới đây của quá trình sản xuất?
  
• Read the passage and choose the correct answer:
  Previously on the ground of the present structure was Norodom Palace built in 1868 as a residence of the French- Governor General of Cochinchina. On September 7, 1954 Norodom Palace was renamed the Independence Palace and became the Presidential Palace in which President Ngo Dinh Diem of the Sai Gon administration and his family lived and worked. In February 1962, a dissident of the Diem regime launched an air bombardment of the palace and heavily damaged it. After that, Diem decided to demolish the damaged structure and built a new one which was designed by Western-trained architect Ngo Viet Thu. The construction was undertaken by Sai Gon sappers and completed in 1966. At 11:30 on April 30, 1975, tanks of the Liberation Army over-rim the palace. The then Sal Con president. Mr. Duong Van Minh, who had just assumed the post of president together with his 45-member cabinet surrendered unconditionally. After the liberation of Sai Gon, the Independence Palace was turned into the Headquarters of Municipal Military Administrative Committee. In December 1975, the palace was the venue of a consultative conference for national reunification. To mark the historical significance of that event, the building was renamed Reunification Conference Hall.
  Question. Reunification Conference Hall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
  
• Mùa xuân năm 542 cuộc khởi nghĩa nào xảy ra?
  
• Read the passage and choose the correct answer:
  Previously on the ground of the present structure was Norodom Palace built in 1868 as a residence of the French- Governor General of Cochinchina. On September 7, 1954 Norodom Palace was renamed the Independence Palace and became the Presidential Palace in which President Ngo Dinh Diem of the Sai Gon administration and his family lived and worked. In February 1962, a dissident of the Diem regime launched an air bombardment of the palace and heavily damaged it. After that, Diem decided to demolish the damaged structure and built a new one which was designed by Western-trained architect Ngo Viet Thu. The construction was undertaken by Sai Gon sappers and completed in 1966. At 11:30 on April 30, 1975, tanks of the Liberation Army over-rim the palace. The then Sal Con president, Mr. Duong Van Minh, who had just assumed the post of president together with his 45-member cabinet surrendered unconditionally. After the liberation of Sai Gon, the Independence Palace was turned into the Headquarters of Municipal Military Administrative Committee. In December 1975, the palace was the venue of a consultative conference for national reunification. To mark the historical significance of that event, the building was renamed Reunification Conference Hall.
  Question. What happened to the original structure?