Một máy biến áp 1 pha có N1=1200 vòng, N2=120 vòng . Dây cuốn sơ cấp nối với nguồn điện U1=220V a. Xác định điện áp đầu ra U2 của cuộn thứ cấp b. Muốn diện áp U2=55V thì số vòng dây của dây quốn thứ cấp phải là bao nhiêu?

Các câu hỏi liên quan

1. Robots can our houses when we are away. A.see B.guard C.look at D.look 2. In the future, robots will be able to do more things for us. A.easy B.harder C.complicated D.much difficul 3. I don't agree you that robots will be able to write a letter to an English friend. A. of B.about C. to D. with 4. They will be very useful because they will be able to do everything for us. A.most B.most of C.almost D.almost of 5. "Do you think robots can work longer than people getting tired?" A. but B.with C.without D.of 6. My father always coffee at home instead of going to the coffee shop. A. do B.does C. make D. makes 7. Robots will be able to the personal computer in the future. A.do B.replace C.make D.recognise 8. Nowadays robots can't talk to people or play sport,but in the future I think they . A. can B. could C. will D. do 9. "Will robots be able our voices?" A.to recognise B.recognising C.to recognising D.for recognising 10. Robots can't talk to people or recognise our voices, butscientists are working the solution. A. at B. on C. in D. with 11. Many people think spending money on robots is a complete of time and money. A. cut B.number C.waste D.amount 12. " you walk when you were two?" A. Can B. Could C. Will D. Do 13. These robots can domany things for the such as cleaning streets or watering plants. A.common B.best C.human D.public 14. Home robots can do things repairing things around the house or looking after the garden. A. such B. like C. with D. of 15. " do you think about the new kinds of robots?" A. How B.What C.Why D.When 16. Our future robot will be able to help us the gardening. A.do B.make C. try D.plant 17. "Robots are helping usa lot in industry, education, and in our house" - " " A.I agree with you B.I hope not C.Do you agree with that? D.What about you? 18. "We waste a lot of money and time researching and making robots" " ". A.I think not. B.I don't think so. C.I agree with. D.I don't hope so. 19. We must be careful because some people may userobots . A.do good things B.to do good things C.do bad things D. to do bad things 20. Robots will be very useful for ourlives but they use energy. A.some B.a little C. a few D.too much