Ống dây điện hình trụ có lõi chân không, chiều dài l = 20 cm, có N = 1000 vòng, diện tích mỗi vòng S = 100 cm2. a. Tính độ tự cảm L của ống dây. b. Dòng điện qua cuộn cảm đó tăng đều từ 0 đến 5 A trong 0,1 s. Tính suất điện động tự cảm xuất hiện ttrong ống dây. c. Khi cường độ dòng điện qua ống dây đạt tới giá trị I = 5 A thì năng lượng tích lũy trong ống dây bằng bao nhiêu?

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