Một quả cầu nhỏ khối lượng m=0,25g mang điện tích q = -2,5 10-9C được treo bằng sợi dây không giãn và đặt vào điện trường đều E có đường sức nằm ngang E =106V/m. Khi quả cầu cân bằng, dây treo hợp với phương thẳng đứng một góc bằng bao nhiêu . Lấy g = 10m/s2. Tính lực căng dây

Các câu hỏi liên quan

Exercise 5 : Rewrite the sentences without changing the meaning 1. Huyen My sings beautifully. Her sister sings more beautifully than her. (AS ... AS) ............................................................................................................. 2. The new sculpture is 4 metres high. The old sculpture is 4.2 metres high. (AS ... AS) .................................................................................................................................... 3. I usually stayed up late to watch football matches last year, but now I don’t. → I used...................................................................................................................... 4. There were some trees in the field, but now there aren’t any. → There used .............................................................................................................. 5. They have very little money. They are happy. (in spite of) .................................................................................................................................... 6. My foot was injured. I managed to walk to the nearest village. (although) .................................................................................................................................... 7. Do you enjoy listening to music? -> Are …………………….…………………………… 8. The blue dress is cheaper than the red one.  The red dress isn’t ……………………………………… 9. Mr. Hai usually has stomach problems. He eats dinner very close to the bedtime. (so) ……………………………………………………………………………………… 10. My dad has a lot of carved eggs. He has never sold any of them. (but) ……………………………………………………………………………………………… 11. I am interested in watching TV in the evening .-> I enjoy… …………………………………………………………………………………. 12. Titanic is a really good movie. It is not for anyone under the age of sixteen. (However) ………………………………………………………………………………………